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It is a great pleasure to announce the publication by McGraw-Hill of my new NEC 2011 guidebook. Reader feedback will be appreciated --



My second McGraw-Hill book for electricians, Troubleshooting and Repairing Commercial Electrical Equipment, now available from Amazon --






Now I've written a third McGraw-Hill book, out soon. The title is The Electricians's Trade Demystified. It is available for pre-order from Amazon. Click below --



You Can Pass Your Journeyman or Master Electrician's License Exam the First Time You Take It

Enroll in David Herres Electricians' Licensing Exam Course

(Details at electriciansexamprep.com )








MikeHolt.com

Wilderness Light Photography: Custom, commercial, landscape, nature, weddings, portraits, stock images by Judith Howcroft -- wildernesslightstockphotos.com


Order Electricians' Books Online --

Electricians' Books


Order Satellite Dish Installation Tools Online --

Summit Source

Order Klein Electricians' Tools Online --

Klein Tools


Order Greenlee Electricians' Tools Online --


Order Ridgid Electricians' Tools Online --


Order Milwaukee Electricians' Tools Online --

Milwaukee 49-22-4085 17 Piece Deluxe Electricians' Hole Saw Kit

Milwaukee 49-22-4085 17 Piece Deluxe Electricians' Hole Saw Kit

Milwaukee 49-22-4085 17 Piece Deluxe Electricians' Hole Saw Kit Since its founding in 1924, Milwaukee has focused on a single vision: to produce the best heavy-duty electric power tools and accessories available to professional user. Today, the Milwaukee name stands for the highest quality, durable and reliable professional tools money can buy. This deluxe 17 piece Electricians' Hole Saw Kit has the ultimate range of diameters available. The 12 diameters include: 5/8 inch, 3/4 inch, 7/8 inch, 1 inch, 1-1/8 inch, 1-1/4 inch, 1-3/8 inch, 1-1/2 inch, 1-3/4 inch, 2 inch, 2-1/2 inch, and 3 inch. The kit also includes arbor 49-56-7000 for hole saws up to 1-3/16 inch and arbor 49-56-7140 for hole saws 1-1/4 inch and larger. Additionally the kit has three pilot bits 49-56-8000 and an impact resistant plastic carrying case. The case is also sold separately as 48-55-0784. The hole saws in this kit are of the 6 teeth per inch design. Milwaukee 49-22-4085 17 Piece Deluxe Electricians' Hole Saw Kit Features: • Deluxe assortment of 12 hole saws, two arbors, and three pilot bits • Hole Saws: 5/8 in., 3/4 in., 7/8 in., 1 in., 1-1/8 in., 1-1/4 in., 1-3/8 in., 1-1/2 in., 1-3/4 in., 2 in., 2-1/2 in., 3 in.




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Electriciansparadise -- More Common Electrical Deficiencies Found by New Hampshire Electrical Inspectors

10.) Clearances working clearances, headroom, dedicated space.

A number of concerns relating to the clearance issues of Section 110.26 are often overlooked in the field. This section requires that sufficient access and working space be provided about electrical equipment to provide ready and safe operation and maintenance of the equipment.

The depth of working space described in Section 110.26(A)(1) is required about equipment operating at 600 volts or less to ground that may require examination, adjustment, servicing, or maintenance while energized. The depth of the space must be determined in accordance with Table 110.26(A)(1) which is based on the conditions described in the table notes.

Section 110.26(A)(2) "Width of Working Space" requires the working space to be at least 30 inches in width or the width of the equipment whichever is greater. This section further requires that the space permit the door or hinged panel of the equipment to open at least 90 degrees.

Section 110-26(A)(3) "Height of Working Space" requires the height of the working space to be at least 6 feet 6 inches, measured from the floor, grade, or platform, or the actual height of the equipment itself which ever is greater. Associated equipment that is located within the working space is not permitted to extend more than 6 inches beyond the front of the electrical equipment.

Section 110.26(B) "Clear Spaces" requires that space about electrical equipment be kept clear and to not allow the space to be used for storage.

Section 110.26(F) "Dedicated Equipment Space" requires that switchboards, panelboards, distribution boards, and motor control centers be located in dedicated spaces and be protected from damage. Section 110.26(F)(1)(a) mandates a clear space that is the depth and width of the equipment that extends to height of 6 feet above the equipment or the structural ceiling which ever is lower. Only equipment associated with the electrical installation is permitted in this space. Where the structural ceiling height is greater than 6 feet, 100.26 (F)(1)(b) permits foreign systems above the six foot space where protection from leaks, breaks or condensation has been provided.


11.) Failure to re-identify the white conductor in cables installed for the purpose of switching, employing the white conductor as an ungrounded conductor.

200.7 Use of Insulation of a White or Gray Color or with Three Continuous White Stripes.

(C) Circuits of 50 Volts or More. The use of insulation that is white or gray or that has three continuous white stripes for other than a grounded conductor for circuits of 50 volts or more shall be permitted only as in (1) through (3).
(1) If part of a cable assembly and where the insulation is permanently re-identified to indicate its use as an ungrounded conductor, by painting or other effective means at its termination, and at each location where the conductor is visible and accessible. Where used in the manner the identification shall encircle the insulation and be a color other than white, gray or green.
(2) Where a cable assembly contains an insulated conductor for single-pole, 3-way or 4-way switch loops and the conductor with white or gray insulation or a marking of three continuous white stripes is used for the supply to the switch but not as a return conductor from the switch to the switched outlet. In these applications, the conductor with white or gray insulation or with three continuous white stripes shall be permanently re-identified to indicate its use by painting or other effective means at its terminations and at each location where the conductor is visible and accessible.

12.) The terminating of more than one grounded conductor under a single terminal.

Grounded Conductor Terminations 408.41

It is not uncommon to find the termination of more than one grounded conductor under a single terminal, in a panelboard. The NEC, as well as the manufacturer, limits terminating the grounded conductor in a panelboard to a single conductor per terminal. Unless you are dealing with parallel grounded conductors under a terminal designed for the purpose, each grounded conductor shall terminate within the panelboard in an individual terminal that is not used for another conductor.


13.) The failure to support luminaires to the ceiling grid in suspended ceilings.

Means of Support 410.16

410.16 (C) Suspended Ceilings
Luminaires (fixtures) installed in suspended ceilings that are required to be chained or tied to the structure, either by the local authority or the job specifications, are often not secured to the grid. Section 410.16 (C) requires the framing members of suspended ceilings be secured to each other and to the building structure at appropriate intervals. This Section also requires that the luminaires be securely fastened to the ceiling framing members either by bolts, screws, rivets, or listed clips identified for use with the type of ceiling framing members and luminaires (fixtures). Unless the luminaires are completely supported independent of the grid system they must secured to the grid system.


14.) The flexible connection to emergency system equipment in hospitals.

517.30 (C) (3) Mechanical Protection of the Emergency System>

Too often there is a failure to recognize and install a compliant wiring method delivering power for emergency system luminaires in locations covered under applications defined in 517.30(A). The use of unprotected flexible metal raceways or cable methods is only permitted under specific conditions. The failure to recognize this requirement appears to come from a misunderstanding of the language found in Section 517.30(C)(3)(3)d. The permitted method depends upon the conditions and circumstances related to the installation and choice of the method. The intent is to protect the integrity of the emergency system from adverse conditions, particularly potential physical damage.

517.30(C)(3) Mechanical Protection of the Emergency System.

The wiring of the emergency system in hospitals shall be mechanically protected. Where installed as branch circuits in patient care areas, the installation shall comply with the requirements of 517.13(A) and 517.13(B). The following methods shall be permitted:

(3) Listed flexible metal raceways and listed metal sheathed cable assemblies in any of the following:
d. Where necessary for flexible connection to equipment

An example of the abuse of the permission to install a flexible cabling method is when luminaires fed from the emergency branch circuits are connected from ceiling outlets using a flexible wiring method. The language specifically indicates: "where necessary for flexible connection." The intent is clear that it is only permitted "where necessary" not where convenient, possible, preferred or easier! The option to use a flexible wiring method would have to be "identified" as "necessary" where it relates to the connection of the equipment and "approved" by both State and Local Authorities Having Jurisdiction. If the intention to use a flexible wiring method in this application to connect emergency luminaires is for reasons of convenience, preference, ease of installation, or financial, it is not considered "NECESSARY!"


15.) The mechanical protection of fire pump wiring and control wiring.

695.6 (E) Pump Wiring & 695.14 (E) Control Wiring

Occasionally fire pump installations present a circumstance where the fire pump and controls connected thereto are in the same room but only a short distance away from the fire pump controller. Because of the distance, the wiring methods being used are not always chosen from the methods indicated in Sections 695.6(E) & 695.14(E). These wiring methods included in these sections are intended to assure protection of the integrity of the wiring system from adverse conditions. Electrical Metallic Tubing (EMT), often found, is not one of the approved methods.

695.6(E) Pump Wiring.

All wiring from the controllers to the pump motors shall be in rigid metal conduit, intermediate metal conduit, liquidtight flexible metal conduit, or liquidtight flexible nonmetallic conduit Type LFNC-B, listed Type MC cable with an impervious covering, or Type MI cable.

695.14(E) Control Wiring

All electric motor-driven fire pump control wiring shall be in rigid metal conduit, intermediate metal conduit, liquidtight flexible metal conduit, liquidtight flexible nonmetallic conduit Type B (LFNC-B), listed Type MC cable with an impervious covering, or Type MI cable.


16.) The location of the disconnecting means for Emergency Systems.

225.31 Disconnecting Means, 225.32 Location and 700.12 (B) (6) Outdoor Generator Sets

It is not uncommon to find a disconnecting means that has been improperly located for an Emergency System (Article 700) feeder which has been supplied from an outdoor housed generator. By the definition in Article 100 the conductors supplying an emergency system from a "separately derived system," in this case a generator, are considered as "feeder" conductors. Where the generator is located outdoors, the conductors would be considered as "outdoor feeder conductors" which are subject to the requirements of Article 225, Outdoor Feeders and Branch Circuits.

The scope of Article 225 (225.1) 225.31 states that a means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure. The first sentence of 225.32 requires the disconnecting means to be located either inside or outside of the building or structure served or where the conductors pass through the building or structure. The second sentence in this section notes that the disconnecting means must be at a readily accessible location nearest the point of entrance of the conductors.

The confusion typically comes in when the language in 700.12(B)(6) is applied improperly. This section, by the format of Code in 90.3, can supplement or amend Chapters One though Four. At first glance, one gets the impression that a disconnecting means that is located under or within the housing of an outdoor generator set can be used as the disconnecting means required by 225.31.

700.12(A) - (F) provide the general requirements for the acceptable sources of power supplying Emergency Systems. 700.12(B)(6) is titled "Outdoor generator sets" and states that "where an outdoor housed generator set is equipped with a readily accessible disconnecting means located within sight of the building or structure supplied, an additional disconnecting means shall not be required where ungrounded conductors serve or pass through the building or structure. One must further recognize that Article 100 defines the term "within sight of" and means that the specified equipment is visible and not more than 50' away. In the case of 700.12(B)(6), the "specified equipment" is the disconnecting means and it must be visible and not more than 50' away from the building served. The definition of "within sight of" in Article 100 does not preclude the use of a window in a panel of the generator housing. However, the disconnecting must be completely visible through the panel window from the building. On one final important note, 225.36 requires the disconnecting means to be suitable for use as service equipment and this requirement in not amended by Article 700.


16.) The separation of Emergency System Conductors from other conductors.

700.9 Wiring, Emergency Systems (700.9 (B) Wiring)

Section 700.9(B) requires that wiring from an emergency source or emergency source distribution overcurrent protection to the loads be kept entirely independent of all other wiring and equipment unless it is otherwise permitted in 700.9(B)(1)-(4). These list items permit the emergency system wiring to be combined with: (1) the wiring from the normal source in transfer switches; (2) the wiring from another source in exit or emergency luminaires (light fixtures); (3) the wiring from another source in common junction box, attached to exit or emergency luminaries (light fixtures); (4) the wiring from a branch circuit supplying unit equipment in a common junction box where the emergency circuit wiring is supplied by the unit equipment.

There is often confusion related to the phrase "wiring from the emergency source to the loads or source distribution overcurrent protection to the emergency loads.." Although a much debated topic, this phrase means that we must keep the wiring from the emergency source to the emergency loads entirely independent of all other wiring or we must keep the wiring from the emergency source distribution overcurrent protection to the emergency loads entirely independent from all other wiring.

One of the common misapplications is to run a feeder from the source to one distribution panelboard and combining the emergency system overcurrent protection in the same enclosure with the legally required standby and/or optional standby overcurrent protection. Under this circumstance the "wiring" to the emergency loads has been combined in the same enclosure with legally required standby and/or the optional standby wiring. Therefore, the wiring to the emergency loads has not been kept "entirely independent of all other wiring." Note that none of the previously discussed items in 700.9(B)(1)-(4) permit this application. You would, however, be allowed to run two or more feeders from the source to separate panelboards. The first panelboard would contain strictly emergency system overcurrent protection and wiring and the other panelboard(s) could contain the legally required standby and/or the optional standby system overcurrent protection and wiring. In this case, the wiring to the emergency loads has been kept "entirely independent of all other wiring."

Where there is no overcurrent protection located at the source, it would be permitted to run one feeder to switchgear containing emergency, legally required standby and optional standby system overcurrent protection where the emergency source distribution overcurrent protection and wiring to the emergency load(s) is located in a separate section of the switchgear. Installed in this manner, the wiring from the emergency source distribution overcurrent protection to the emergency loads has been kept entirely independent of all other wiring.


18.) Emergency, Legally Required and Optional Standby Signs

700.8, 701.9 and 702.8; Signs

There are two types of signs required when there is an on-site emergency, legally required standby or optional standby source. The first sign is a requirement of "(A)" in all three sections. It must be placed at the location of the service entrance equipment and identify the location and type of the onsite power source.

Both 700.8(A) and 701.9(A) include an exception for the sign where individual unit equipment (battery packs) are the onsite power source.

The second sign is a requirement of "(B)" in all three sections and it applies where the grounded circuit conductor connected to the power source is connected to a grounding electrode conductor at a location that is remote from the power source. One common installation where the grounding connection to a grounding electrode conductor that is remote from the power source is where the power source is not installed as a "separately derived system" (see Article 100 definition). In this application the onsite power source grounded conductor has a solid connection to the normal system grounded conductor (not switched by the transfer switch) and the grounding connection to the grounding electrode conductor is typically being made to the normal supply grounded conductor at the service or other normal supply location.

Where the requirement of "(B)" applies, the sign must be placed at the grounding location which is where the grounding electrode conductor connects to the grounded conductor. The sign must identify any emergency, legally required standby or optional standby sources as well as any normal sources that are connected at that location.


19.) The sealing of underground raceways or raceways that are exposed to different temperatures.

Although they are often overlooked, there are specific requirements in the NEC with regard to sealing underground raceways entering buildings or where condensation is created in raceways by the exposure to different temperatures within buildings or where a raceway passes from outdoor to indoor locations.

230.8 requires a service raceway entering a building or structure from an underground distribution system to be sealed in accordance with 300.5(G) (at either or both ends). Water can enter raceways through couplings or it can build up from condensation resulting from the exposure to different temperatures. How ever the water accumulates within the raceway, the intent of the requirement is to prevent water from entering the service equipment via the underground raceway system. A sealant such as duct seal or other types identified for use with the conductor or cable insulation, shield or other components must be used to seal the ends of raceway and it should not have deteriorating effect on the insulation.

300.5 provides requirements for underground installations and 300.5(G) states that conduits or raceways through which moisture can contact live parts shall be sealed or plugged at either or both ends. The requirements of this section are specific to where moisture can contact live parts so consideration must be given to how the conduit or raceway is installed. Not all underground conduits or raceways are installed in a manner that moisture would actually contact a live part. An example would be where an underground raceway enters below the equipment and then bends upward to the bottom of the equipment or a conduit body is used and then the raceway attaches the bottom of the equipment enclosure.

300.7(A) applies to raceways that are exposed to different temperatures. This section requires sealing with an approved material to prevent the circulation of warm air to a colder section of a raceway or sleeve where any portion of the raceway or sleeve is subject to different temperatures and where condensation is known to be a problem. Cold storage areas of buildings, passing from the interior to an exterior location and entering a walk-in cooler are examples of where condensation can occur in raceways due to the difference in temperature. A suitable compound at a conduit body or junction box installed in the raceway system just before it enters the colder location can serve as sealing means. As noted above, the compound must not cause deterioration of the conductor insulation.


--END--


Books for electricians --

Here is a selection of the most significant electricians' books available online today, at the best prices around. Clicking on any logo provides access to reviews and ratings by electricians. A good place to start is with the 2008 NEC Handbook, which contains the complete text of the current code plus extensive commentary, diagrams and illustrations. Other books of interest for the electrician are available as well.

Low Voltage, Telecom, Fire Alarm Books --


This site is created and conducted By David Herres, NH Master Electrician License #11335M

E-mail: electriciansparadise@hughes.net


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It is a great pleasure to announce the publication by McGraw-Hill of my new NEC 2011 guidebook. Reader feedback will be appreciated --






MikeHolt.com

Wilderness Light Photography: Custom, commercial, landscape, nature, weddings, portraits, stock images by Judith Howcroft -- wildernesslightstockphotos.com


Order Electricians' Books Online --

Electricians' Books


Order Satellite Dish Installation Tools Online --

Summit Source

Order Klein Electricians' Tools Online --

Klein Tools


Order Greenlee Electricians' Tools Online --


Order Ridgid Electricians' Tools Online --


Order Milwaukee Electricians' Tools Online --

Milwaukee 49-22-4085 17 Piece Deluxe Electricians' Hole Saw Kit

Milwaukee 49-22-4085 17 Piece Deluxe Electricians' Hole Saw Kit

Milwaukee 49-22-4085 17 Piece Deluxe Electricians' Hole Saw Kit Since its founding in 1924, Milwaukee has focused on a single vision: to produce the best heavy-duty electric power tools and accessories available to professional user. Today, the Milwaukee name stands for the highest quality, durable and reliable professional tools money can buy. This deluxe 17 piece Electricians' Hole Saw Kit has the ultimate range of diameters available. The 12 diameters include: 5/8 inch, 3/4 inch, 7/8 inch, 1 inch, 1-1/8 inch, 1-1/4 inch, 1-3/8 inch, 1-1/2 inch, 1-3/4 inch, 2 inch, 2-1/2 inch, and 3 inch. The kit also includes arbor 49-56-7000 for hole saws up to 1-3/16 inch and arbor 49-56-7140 for hole saws 1-1/4 inch and larger. Additionally the kit has three pilot bits 49-56-8000 and an impact resistant plastic carrying case. The case is also sold separately as 48-55-0784. The hole saws in this kit are of the 6 teeth per inch design. Milwaukee 49-22-4085 17 Piece Deluxe Electricians' Hole Saw Kit Features: • Deluxe assortment of 12 hole saws, two arbors, and three pilot bits • Hole Saws: 5/8 in., 3/4 in., 7/8 in., 1 in., 1-1/8 in., 1-1/4 in., 1-3/8 in., 1-1/2 in., 1-3/4 in., 2 in., 2-1/2 in., 3 in.




Order Dewalt Tools Online --



Apple Online Store




Electriciansparadise -- More Common Electrical Deficiencies Found by New Hampshire Electrical Inspectors

10.) Clearances working clearances, headroom, dedicated space.

A number of concerns relating to the clearance issues of Section 110.26 are often overlooked in the field. This section requires that sufficient access and working space be provided about electrical equipment to provide ready and safe operation and maintenance of the equipment.

The depth of working space described in Section 110.26(A)(1) is required about equipment operating at 600 volts or less to ground that may require examination, adjustment, servicing, or maintenance while energized. The depth of the space must be determined in accordance with Table 110.26(A)(1) which is based on the conditions described in the table notes.

Section 110.26(A)(2) "Width of Working Space" requires the working space to be at least 30 inches in width or the width of the equipment whichever is greater. This section further requires that the space permit the door or hinged panel of the equipment to open at least 90 degrees.

Section 110-26(A)(3) "Height of Working Space" requires the height of the working space to be at least 6 feet 6 inches, measured from the floor, grade, or platform, or the actual height of the equipment itself which ever is greater. Associated equipment that is located within the working space is not permitted to extend more than 6 inches beyond the front of the electrical equipment.

Section 110.26(B) "Clear Spaces" requires that space about electrical equipment be kept clear and to not allow the space to be used for storage.

Section 110.26(F) "Dedicated Equipment Space" requires that switchboards, panelboards, distribution boards, and motor control centers be located in dedicated spaces and be protected from damage. Section 110.26(F)(1)(a) mandates a clear space that is the depth and width of the equipment that extends to height of 6 feet above the equipment or the structural ceiling which ever is lower. Only equipment associated with the electrical installation is permitted in this space. Where the structural ceiling height is greater than 6 feet, 100.26 (F)(1)(b) permits foreign systems above the six foot space where protection from leaks, breaks or condensation has been provided.


11.) Failure to re-identify the white conductor in cables installed for the purpose of switching, employing the white conductor as an ungrounded conductor.

200.7 Use of Insulation of a White or Gray Color or with Three Continuous White Stripes.

(C) Circuits of 50 Volts or More. The use of insulation that is white or gray or that has three continuous white stripes for other than a grounded conductor for circuits of 50 volts or more shall be permitted only as in (1) through (3).
(1) If part of a cable assembly and where the insulation is permanently re-identified to indicate its use as an ungrounded conductor, by painting or other effective means at its termination, and at each location where the conductor is visible and accessible. Where used in the manner the identification shall encircle the insulation and be a color other than white, gray or green.
(2) Where a cable assembly contains an insulated conductor for single-pole, 3-way or 4-way switch loops and the conductor with white or gray insulation or a marking of three continuous white stripes is used for the supply to the switch but not as a return conductor from the switch to the switched outlet. In these applications, the conductor with white or gray insulation or with three continuous white stripes shall be permanently re-identified to indicate its use by painting or other effective means at its terminations and at each location where the conductor is visible and accessible.

12.) The terminating of more than one grounded conductor under a single terminal.

Grounded Conductor Terminations 408.41

It is not uncommon to find the termination of more than one grounded conductor under a single terminal, in a panelboard. The NEC, as well as the manufacturer, limits terminating the grounded conductor in a panelboard to a single conductor per terminal. Unless you are dealing with parallel grounded conductors under a terminal designed for the purpose, each grounded conductor shall terminate within the panelboard in an individual terminal that is not used for another conductor.


13.) The failure to support luminaires to the ceiling grid in suspended ceilings.

Means of Support 410.16

410.16 (C) Suspended Ceilings
Luminaires (fixtures) installed in suspended ceilings that are required to be chained or tied to the structure, either by the local authority or the job specifications, are often not secured to the grid. Section 410.16 (C) requires the framing members of suspended ceilings be secured to each other and to the building structure at appropriate intervals. This Section also requires that the luminaires be securely fastened to the ceiling framing members either by bolts, screws, rivets, or listed clips identified for use with the type of ceiling framing members and luminaires (fixtures). Unless the luminaires are completely supported independent of the grid system they must secured to the grid system.


14.) The flexible connection to emergency system equipment in hospitals.

517.30 (C) (3) Mechanical Protection of the Emergency System>

Too often there is a failure to recognize and install a compliant wiring method delivering power for emergency system luminaires in locations covered under applications defined in 517.30(A). The use of unprotected flexible metal raceways or cable methods is only permitted under specific conditions. The failure to recognize this requirement appears to come from a misunderstanding of the language found in Section 517.30(C)(3)(3)d. The permitted method depends upon the conditions and circumstances related to the installation and choice of the method. The intent is to protect the integrity of the emergency system from adverse conditions, particularly potential physical damage.

517.30(C)(3) Mechanical Protection of the Emergency System.

The wiring of the emergency system in hospitals shall be mechanically protected. Where installed as branch circuits in patient care areas, the installation shall comply with the requirements of 517.13(A) and 517.13(B). The following methods shall be permitted:

(3) Listed flexible metal raceways and listed metal sheathed cable assemblies in any of the following:
d. Where necessary for flexible connection to equipment

An example of the abuse of the permission to install a flexible cabling method is when luminaires fed from the emergency branch circuits are connected from ceiling outlets using a flexible wiring method. The language specifically indicates: "where necessary for flexible connection." The intent is clear that it is only permitted "where necessary" not where convenient, possible, preferred or easier! The option to use a flexible wiring method would have to be "identified" as "necessary" where it relates to the connection of the equipment and "approved" by both State and Local Authorities Having Jurisdiction. If the intention to use a flexible wiring method in this application to connect emergency luminaires is for reasons of convenience, preference, ease of installation, or financial, it is not considered "NECESSARY!"


15.) The mechanical protection of fire pump wiring and control wiring.

695.6 (E) Pump Wiring & 695.14 (E) Control Wiring

Occasionally fire pump installations present a circumstance where the fire pump and controls connected thereto are in the same room but only a short distance away from the fire pump controller. Because of the distance, the wiring methods being used are not always chosen from the methods indicated in Sections 695.6(E) & 695.14(E). These wiring methods included in these sections are intended to assure protection of the integrity of the wiring system from adverse conditions. Electrical Metallic Tubing (EMT), often found, is not one of the approved methods.

695.6(E) Pump Wiring.

All wiring from the controllers to the pump motors shall be in rigid metal conduit, intermediate metal conduit, liquidtight flexible metal conduit, or liquidtight flexible nonmetallic conduit Type LFNC-B, listed Type MC cable with an impervious covering, or Type MI cable.

695.14(E) Control Wiring

All electric motor-driven fire pump control wiring shall be in rigid metal conduit, intermediate metal conduit, liquidtight flexible metal conduit, liquidtight flexible nonmetallic conduit Type B (LFNC-B), listed Type MC cable with an impervious covering, or Type MI cable.


16.) The location of the disconnecting means for Emergency Systems.

225.31 Disconnecting Means, 225.32 Location and 700.12 (B) (6) Outdoor Generator Sets

It is not uncommon to find a disconnecting means that has been improperly located for an Emergency System (Article 700) feeder which has been supplied from an outdoor housed generator. By the definition in Article 100 the conductors supplying an emergency system from a "separately derived system," in this case a generator, are considered as "feeder" conductors. Where the generator is located outdoors, the conductors would be considered as "outdoor feeder conductors" which are subject to the requirements of Article 225, Outdoor Feeders and Branch Circuits.

The scope of Article 225 (225.1) 225.31 states that a means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure. The first sentence of 225.32 requires the disconnecting means to be located either inside or outside of the building or structure served or where the conductors pass through the building or structure. The second sentence in this section notes that the disconnecting means must be at a readily accessible location nearest the point of entrance of the conductors.

The confusion typically comes in when the language in 700.12(B)(6) is applied improperly. This section, by the format of Code in 90.3, can supplement or amend Chapters One though Four. At first glance, one gets the impression that a disconnecting means that is located under or within the housing of an outdoor generator set can be used as the disconnecting means required by 225.31.

700.12(A) - (F) provide the general requirements for the acceptable sources of power supplying Emergency Systems. 700.12(B)(6) is titled "Outdoor generator sets" and states that "where an outdoor housed generator set is equipped with a readily accessible disconnecting means located within sight of the building or structure supplied, an additional disconnecting means shall not be required where ungrounded conductors serve or pass through the building or structure. One must further recognize that Article 100 defines the term "within sight of" and means that the specified equipment is visible and not more than 50' away. In the case of 700.12(B)(6), the "specified equipment" is the disconnecting means and it must be visible and not more than 50' away from the building served. The definition of "within sight of" in Article 100 does not preclude the use of a window in a panel of the generator housing. However, the disconnecting must be completely visible through the panel window from the building. On one final important note, 225.36 requires the disconnecting means to be suitable for use as service equipment and this requirement in not amended by Article 700.


16.) The separation of Emergency System Conductors from other conductors.

700.9 Wiring, Emergency Systems (700.9 (B) Wiring)

Section 700.9(B) requires that wiring from an emergency source or emergency source distribution overcurrent protection to the loads be kept entirely independent of all other wiring and equipment unless it is otherwise permitted in 700.9(B)(1)-(4). These list items permit the emergency system wiring to be combined with: (1) the wiring from the normal source in transfer switches; (2) the wiring from another source in exit or emergency luminaires (light fixtures); (3) the wiring from another source in common junction box, attached to exit or emergency luminaries (light fixtures); (4) the wiring from a branch circuit supplying unit equipment in a common junction box where the emergency circuit wiring is supplied by the unit equipment.

There is often confusion related to the phrase "wiring from the emergency source to the loads or source distribution overcurrent protection to the emergency loads.." Although a much debated topic, this phrase means that we must keep the wiring from the emergency source to the emergency loads entirely independent of all other wiring or we must keep the wiring from the emergency source distribution overcurrent protection to the emergency loads entirely independent from all other wiring.

One of the common misapplications is to run a feeder from the source to one distribution panelboard and combining the emergency system overcurrent protection in the same enclosure with the legally required standby and/or optional standby overcurrent protection. Under this circumstance the "wiring" to the emergency loads has been combined in the same enclosure with legally required standby and/or the optional standby wiring. Therefore, the wiring to the emergency loads has not been kept "entirely independent of all other wiring." Note that none of the previously discussed items in 700.9(B)(1)-(4) permit this application. You would, however, be allowed to run two or more feeders from the source to separate panelboards. The first panelboard would contain strictly emergency system overcurrent protection and wiring and the other panelboard(s) could contain the legally required standby and/or the optional standby system overcurrent protection and wiring. In this case, the wiring to the emergency loads has been kept "entirely independent of all other wiring."

Where there is no overcurrent protection located at the source, it would be permitted to run one feeder to switchgear containing emergency, legally required standby and optional standby system overcurrent protection where the emergency source distribution overcurrent protection and wiring to the emergency load(s) is located in a separate section of the switchgear. Installed in this manner, the wiring from the emergency source distribution overcurrent protection to the emergency loads has been kept entirely independent of all other wiring.


18.) Emergency, Legally Required and Optional Standby Signs

700.8, 701.9 and 702.8; Signs

There are two types of signs required when there is an on-site emergency, legally required standby or optional standby source. The first sign is a requirement of "(A)" in all three sections. It must be placed at the location of the service entrance equipment and identify the location and type of the onsite power source.

Both 700.8(A) and 701.9(A) include an exception for the sign where individual unit equipment (battery packs) are the onsite power source.

The second sign is a requirement of "(B)" in all three sections and it applies where the grounded circuit conductor connected to the power source is connected to a grounding electrode conductor at a location that is remote from the power source. One common installation where the grounding connection to a grounding electrode conductor that is remote from the power source is where the power source is not installed as a "separately derived system" (see Article 100 definition). In this application the onsite power source grounded conductor has a solid connection to the normal system grounded conductor (not switched by the transfer switch) and the grounding connection to the grounding electrode conductor is typically being made to the normal supply grounded conductor at the service or other normal supply location.

Where the requirement of "(B)" applies, the sign must be placed at the grounding location which is where the grounding electrode conductor connects to the grounded conductor. The sign must identify any emergency, legally required standby or optional standby sources as well as any normal sources that are connected at that location.


19.) The sealing of underground raceways or raceways that are exposed to different temperatures.

Although they are often overlooked, there are specific requirements in the NEC with regard to sealing underground raceways entering buildings or where condensation is created in raceways by the exposure to different temperatures within buildings or where a raceway passes from outdoor to indoor locations.

230.8 requires a service raceway entering a building or structure from an underground distribution system to be sealed in accordance with 300.5(G) (at either or both ends). Water can enter raceways through couplings or it can build up from condensation resulting from the exposure to different temperatures. How ever the water accumulates within the raceway, the intent of the requirement is to prevent water from entering the service equipment via the underground raceway system. A sealant such as duct seal or other types identified for use with the conductor or cable insulation, shield or other components must be used to seal the ends of raceway and it should not have deteriorating effect on the insulation.

300.5 provides requirements for underground installations and 300.5(G) states that conduits or raceways through which moisture can contact live parts shall be sealed or plugged at either or both ends. The requirements of this section are specific to where moisture can contact live parts so consideration must be given to how the conduit or raceway is installed. Not all underground conduits or raceways are installed in a manner that moisture would actually contact a live part. An example would be where an underground raceway enters below the equipment and then bends upward to the bottom of the equipment or a conduit body is used and then the raceway attaches the bottom of the equipment enclosure.

300.7(A) applies to raceways that are exposed to different temperatures. This section requires sealing with an approved material to prevent the circulation of warm air to a colder section of a raceway or sleeve where any portion of the raceway or sleeve is subject to different temperatures and where condensation is known to be a problem. Cold storage areas of buildings, passing from the interior to an exterior location and entering a walk-in cooler are examples of where condensation can occur in raceways due to the difference in temperature. A suitable compound at a conduit body or junction box installed in the raceway system just before it enters the colder location can serve as sealing means. As noted above, the compound must not cause deterioration of the conductor insulation.


--END--


Books for electricians --

Here is a selection of the most significant electricians' books available online today, at the best prices around. Clicking on any logo provides access to reviews and ratings by electricians. A good place to start is with the 2008 NEC Handbook, which contains the complete text of the current code plus extensive commentary, diagrams and illustrations. Other books of interest for the electrician are available as well.

Low Voltage, Telecom, Fire Alarm Books --


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