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Electriciansparadise -- Nineteen Most Common Electrical Deficiencies Found by New Hampshire Electrical Inspectors

1.) A grounding electrode conductor that is attached to the grounded conductor or equipment grounding terminal bar of a remote panelboard.

Note: This item has been part of the most common deficiencies since 1999. Although this is not found as often as it was prior to 1999, it still is an issue that is misunderstood and therefore bares consideration.

"250.24(A) System Grounding Connections. A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).

(1) General. The connection shall be made at any accessible point from the load end of the service drop or service lateral to and including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means."

Example: a single family dwelling that has an attached garage. There is a 200 ampere main disconnect located in the garage and a 4/0 aluminum SER Cable has been run to a panelboard located in the basement. A grounding electrode conductor has been attached to the metal water pipe feeding the dwelling and run to the panelboard located in the basement. The grounding electrode conductor has been terminated on the grounded conductor (neutral) terminal or equipment grounding bus of the panelboard. This panelboard, being a remote panelboard, has been supplied by a feeder and is not part of the service. Therefore, the grounding electrode conductor should have been run to the 200 ampere service disconnect in the garage.


2.) The bonding of metal water piping in the vicinity of separately derived systems.

250.104 Bonding of Piping Systems and Exposed Structural Steel.

(A) Metal Water Piping.
(4) Separately Derived Systems. The grounded conductor of each separately derived system shall be bonded to the nearest available point of the interior metal water piping system(s) in the area served by each separately derived system. This connection shall be made at the same point on the separately derived system where the grounding electrode conductor is connected. Each bonding jumper shall be sized in accordance with Table 250.66.

Exception: A separate water piping bonding jumper shall not be required where the effectively grounded metal frame of a building or structure is used as the grounding electrode for a separately derived system and is bonded to the metallic water piping in the area served by the separately derived system.

Example: Any metallic water pipe located in the vicinity served by the separately derived system must be bonded to the grounded conductor connection of the separately derived source. The metal water piping serving an office kitchenette with 120-volt power provided from a nearby transformer must be bonded to the transformer grounded connection.


3.) The non-use of expansion fittings in Rigid Non-Metallic (PVC) conduits that are subject to thermal expansion and contraction.

Sections 300.7(B) and 352.44 require the use of an expansion fitting in exposed straight runs between securely mounted items such as boxes, conduit bodies and elbows of non-metallic raceways that are subject to large temperature variations. The expansion fitting is required when the length change, in accordance with Table 352.44(A) is 0.25" or greater.

Example: in a 100' run of Rigid Non-Metallic Conduit, that is exposed to a 100 degree difference in temperature, the computed expansion is 4.1". With a 100 degree difference of temperature and in an area not exposed to direct sunlight the length change in a 6' 1" section of Non-Metallic conduit will be more than 0.25".


4.) The non-use of expansion fittings on conduits emerging from the earth where attached to fixed equipment and are installed in locations that are subject to ground movement.

Section 300-5(J) requires that conduits in these locations be arranged to prevent damage to the enclosed conductors. The Fine Print Note below (J) recognizes the use of expansion fittings in conduits to achieve this purpose.

Example: An underground service (lateral) to a dwelling unit installed in 2" Rigid Non-Metallic Conduit that is directly attached to a meter enclosure mounted, outside, on the dwelling unit wall. The issue of areas that are subject to ground movement has always been and will continue to be difficult to define due to varying conditions.

There are many factors that come into play when you consider whether or not the conductors enclosed in the raceway are subject to damage by ground movement. Some of the things that come to mind are; how deep the frost penetration is, has the earth around the conduit been backfilled and compacted or just backfilled and how deep the conduits are buried in the earth. Depending on where you are located in the State of New Hampshire the conditions will vary. Many times this issue is left to the local authority. He/she would be most familiar with the conditions in their area.


5.) The improper installation and securing of expansion fittings in runs of Rigid Non-Metallic (PVC) Conduit.

Section 110.3 (B) requires that listed or labeled products be installed in accordance with their listing or labeling. Quite often when the expansion fitting mentioned in items #3 and #5 is installed; it is secured on the wrong end. The manufacturer’s listing requires that the expansion fitting be secured on the "bell" (fixed) end. Notice should be taken when mounting the fitting in a vertical position. The fitting must be installed with the "bell" end up and the sliding or expanding end below. On one final note, the conduit must meet the securing requirements of the applicable raceway article.


6.) Use of electrical equipment without following the manufacturer’s instructions.

All too often the information provided on or with electrical equipment is overlooked by the installers. If specific installation requirements are provided by the manufacturer they must be adhered to by the installer. Section 110.3(B) requires that electrical equipment be installed in accordance with any installation instructions that may be included in the listing or labeling. It would be a Code violation to not follow these instructions so don't throw them away until you have read them.


7.) The non-bonding of service raceways and equipment.

Note: This item has been part of the most common deficiencies since 1999. Although this is not found as often as it was prior to 1999, it still is an issue that is misunderstood and therefore bares consideration.

Section 250.92(A) requires the non-current carrying metal parts of service equipment, indicated in Section 250-92(A)(1), (2) and (3), to be effectively bonded together. Section 250.92(A)(1) speaks to service raceways and Section 250.92(A)(2) speaks to all service equipment enclosures containing service conductors, including meter fittings, boxes, and the like interposed in the service raceway. Section 250.92(B) describes the methods that will ensure the electrical continuity of the service equipment. As described in Section 250.92(B) standard locknuts or bushings are not an acceptable means for the bonding required by this section.

Example: a structure that has an overhead service. The service entrance conductors splice to the service drop and run down an EMT raceway to the meter enclosure. The EMT raceway is secured to the hub on top of the meter enclosure with a compression connector. The EMT raceway runs from the back of the meter enclosure directly through the wall and attaches to the service disconnect enclosure with standard connectors, locknuts and plastic bushings on both ends. The problem here is a bonding fitting should have been used on one end of the EMT raceway running from the meter enclosure to the service disconnect enclosure to bond the raceway. The EMT riser is effectively bonded by the threaded hub on the top of the meter enclosure. If there were any wireways or boxes installed in the raceway system they would be required to be bonded as well. Section 250.102(C) requires equipment bonding conductors on the supply side of the service to not be smaller than the sizes shown in Table 250.66.


8.) The non-use of a locking type disconnect for submersible well pump motors.

Section 430.102(A) requires the installation of a disconnecting means in sight from the motor controller location that disconnects the controller. In the case of the typical residential submersible well pump installation the controller would be the pressure switch on the water storage tank. Section 430.102(B) requires a disconnecting means to be in sight from the motor location to disconnect the motor. Article 100 defines "in sight from" to be visible and within 50'so there should be a disconnecting means that is visible and located no more than 50' from the pump motor. Normally it is impracticable to accomplish this so under the Exception to 430.102(B) you are permitted to eliminate the motor disconnect if the location is impracticable and the controller disconnect is capable of being locked in the open position. The provisions for locking or adding a lock to the disconnecting means shall be installed at the switch or circuit breaker used as the disconnecting means and shall remain in place with or without the lock installed.

Example: a submersible well pump has been installed to supply the domestic water for a dwelling unit. The pump cable runs from the well head to the dwelling unit basement where it connects to the load side terminals of the pressure switch located on the water storage tank. A branch-circuit has been run about 35' from a panelboard that is not visible from the water storage tank location, to a snap switch located next to the water storage tank. The conductors on the load side of the snap switch run to the line side terminals of the pressure switch. In this case the snap switch would be the controller disconnect switch required by 430.102(A). If the panelboard were visible for the entire 35' from the water storage tank location the circuit breaker could also serve as the controller disconnect. There is no disconnect within sight from the well head, in the installation described, so in order to meet the exception to 430.102(B) a device capable of locking the snap switch in the open position would be required. There are products available on the market that will allow a lock to be placed on a standard snap switch assembly or circuit breaker.


9.) The improper connection of septic pumps.

There are several different problems that can stem from septic pump installations. First, Section 430.102(A) requires the installation of a disconnecting means in sight from a motor controller location that disconnects the controller. In the case of the typical residential septic pump installation the controller would be the float switch in the pump tank. Section 430.102(B) requires a disconnecting means in sight from a motor location to disconnect the motor. In this case it is possible to satisfy both requirements with one disconnecting means located at the tank as the controller and the motor are both within site of the disconnecting means. Article 100 defines "in sight from" to be visible and within 50'. So there must be a disconnecting means that is visible and located no more than 50' from the pump tank. In most residential cases the pump and controller (float switch) are inserted into a receptacle located near the tank so the attachment cap for the controller and pump cord can serve as the disconnecting means.

Most often the homeowner does not want to see a pedestal with a receptacle and cords so the attachment caps are cut off and the cords are wired directly (hard wired) into a junction box that is located in the tank. If the pump and controller have been hard wired many times there is no disconnect at all located within site from the motor or controller. In some cases the manufacturer prohibits the removal of the cord cap and float assembly end and this would be a violation of the manufacturer's requirements. In other cases the receptacle has been installed inside the pump tank. Before making this kind of installation, consideration should be given to the issues of accessibility and corrosion. Also, depending on the size of the system there may be sufficient hazardous vapor in the pump chamber to classify the location. The classified locations are more common in commercial and industrial applications.


More Electrical Deficiencies

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

E-mail: electriciansparadise@hughes.net


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