National Electrical Installation Standards

An existing installation has (3) separate oil-filled single phase transformers (pad-mounted) wired together as delta-wye in an overhead bus structure. All (3) transformers are protected with (1) overcurrent relay. My question is: does each transformer require it's own independent overcurrent protection? How does NEC-450.7 relate to this? Barry Calloway
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Is it required in 2017 NEC to provide a disconnect means on the land at the entrance to a private pier or dock? Rick Balson
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In my inspections I have come across Liquid flex used to connect the generators conductors from generator to junction box on back of homes, the problem is I have turned down the inspection when the GAS piping is uses with tie wraps to hold and support the Sealtight. Strapping the sealtight to a gas line is using another’s trades material to hold and support workmanship. The readers get this question daily, and they have chosen to use another inspectors who allows this practice. Can you Cite code article to cover this practice? Bill Schell
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Is a flammable paint locker required to be grounded? Richard Peraza
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When you are cutting in a dead-end 3 way or a reversed 3 Way should you send the power or you switch leg back to the other side on the three wire and which wire should you use to send it or does it matter? Eugene Hullender
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Greetings, I have a question regarding leaving live lamp sockets un-lamped. In my specific case, the luminaire has been a sconce containing 2 GU24 sockets for use with A19 lamps. The following link is not the exact sconce but has the same characteristics: open on top, closed/tight to wall on sides and bottom. It's mounted ~5.5' AFF in a hallway setting and the luminaire is wired with 120V power. The reason for leaving the second socket un-lamped is energy savings and sufficient illuminance from a single lamp. Can you tell me whether the NEC allows one of the sockets be left un-lamped? Can you tell me where in the NEC guidance might be provided? My specific applications are using the 2008 and 2011 versions of the NEC. Thanks for any help you can provide. Brennan Donovan
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Charlie we are having a discussion in the shop about metal boxes having to be listed. Is that right? I can't find a specific requirement for that. Thanks Amy
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I search throughout the code, and found requirements for the heights of service panel .But is there a requirements of how high it must be from the floor up to bottom of panel? Gordon
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Where can I find in the NEC the area that explains that it is not allowed to run the service line at the house from the weather head to the electric meter behind aluminum siding trim? Steve Harris
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Re: CQD answer published Thursday, March 29, 2018 -Cooking appliance Tap Conductors 1) Good morning, If I understand 210.19(A)(3) Exc. No. 1 correctly, your answer did not specify the conductors referenced in the exception are those supplied with the appliance and not field-installed branch circuit conductors such as 12/2 NM-B cable. I believe the last sentence of the exception indicates this intent. Maybe this is a place where we could clarify the language a bit? Yeah, I know, you look forward to my Public Input! Thanks for your service. J Grant Hammett 2) I agree with the answer given for the tap conductors supplying the microwave from the range branch circuit. In addition, the tap conductors would have to be hard-wired to the microwave, otherwise 210.21(B)(3) would apply if installing a receptacle outlet. The receptacle would need to be rated for the branch circuit overcurrent protection per Table 210.21(B)(3). Tom Sieracki
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Charlie, I read your Code Question of the Day nearly every day and learn much about how the code is interpreted. Now I have a question which has not been discussed so far and is something which may be a future compliance problem with LED lighting and would like your take on it. In a site inspection where new LED surface mounted fixtures were specified, the electrical contractor noted he would need to punch a larger hole in the back of the fixture so wiring within the outlet box would be accessible. Per Article 410.24 (B) the box itself would is not the only means of support so he was correct. He also noted this would be fine with a fluorescent (Electric-Discharge) fixture and is normal practice as they have ballast cavities running end to end, but LED’s elements are often only fed from one end and don’t need a channel. The manufacturers installation instructions show the wire pigtails coming out of the outlet box to the fixture through a rounded edge ¾” wiring opening and show wiring connections made within a small protective cover adjacent to the LED driver. If a hole large enough to allow access to the outlet box was punched into this particular fixture there is room between the 2 linear LED elements, this larger hole will remove the grounding screw along with the means to secure the provided wireway cover. This modification of the light body may violate the manufacturer’s instructions so probably the warranty as well. Without the wireway cover, the wiring would then be exposed within the light with nothing to enclose them so the contractor will then have to push the wire and wire nuts back into the box so they are not visible within the body of the light. These instructions are from a very reputable lighting manufacturer and would seem reasonable since all the wiring connections would be made outside of the box within the light fixture wiring cavity and would be nothing in the box which needs access once the light is installed. (I have included this page for you to reference.) Has the manufacturer created these instructions with an obvious code violation? With LED’s becoming the normal light fixture type, they are getting narrower where especially in strip lights the fixture body is often not as wide as an outlet box and placement of the LED element arrays are not always laid out where compliance with 410.24 (B) may become more difficult if not impossible. Do you know of any exceptions available within the code which would allow the manufactures instructions to be used and produce a complaint installation? Look forward to your response. Donald (Don) Hopkins PE, FPE
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Do I need to install gfci protection if I replace a dishwasher? The dishwasher circuit is existing and is a receptacle under the sink next to the dishwasher and met previous editions of the code. Thanks, Zach
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On a residential service what is the maximum distance the service conductors can travel with in the structure without over current protection. Rich Kortkamp
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In a hand hole. Is it within code to have both power (which is spliced) and telecom cables in the same hole or should each have its own hand hole? Chris Wronski
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I just replaced a bad contactor on a made in USA drive that came from the manufacture with bypass function. It has two 75 Horsepower contactors for the drive input and bypass but only a 60 Horsepower contactor for the drive output. I replaced this with a 75 HP contactor. I asked the service technician about this deliberate under sizing and he stated being the 60 HP contactor pulls in before drive starts its output that it is okay. Often these drives have to run all day @ 100 % speed so the ampere draw is up there. [They reduce speeds at night and weekends] I know that these companies get away with murder undercutting the NEC but even this does not appear to be right . When I infrared inside drive cabinets that are in an air conditioned spaces their conductors are 10 to 15 degrees warmer then then the properly sized supply and load conductors. You would think that with all of the energy codes they would look into it . I called one of these companies up and asked why do they have 2 cooling fans that are mounted to a six by 8 foot drive enclosure running 24/7. They were extremely upset that I questioned them on that on that. These cabinets supply power to 18 pulse 150 HP VFD'S for chilled water pumps that do not run in the winter but our company prefers to have drives energized all year. Some drive companies install a thermostat that only turn fans on at around 80 degrees. Thanks Tom Grabowski
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