National Electrical Installation Standards

Re: CQD answer published August 9 & August 21, 2018 - Service Equipment 4 In response to the article debating whether a 3 wire single phase conductor set is allowed to a structure as opposed to 4 wire set, the petitioner referenced a " service pedestal" with an overcurrent device . We were all taught in apprenticeship any conductors on load side of an overcurrent device are feeders. Unfortunately this is only partially true. If this pedestal is installed and maintained by a serving utility, then the utility is responsible for declaring the "service point", as defined in NEC article 100 definitions as the point of demarcation where utility service ends and customer responsibility begins. The placement of an overcurrent device installed on the line side (utility) of a system does not render the conductors from said overcurrent device to the structure as feeders, but as service conductors if the utility declares the load side of the overcurrent device as the service point, which is the case with many utility supplied pedestals. This rendering of "service point" is completely the decision of the utility and not the NEC, nor any customer or other party. We can only declare "feeder" when and where the utility states it will be. Thank you much for this opportunity to clarify a greatly misunderstood area. Kelly Stockwill
View Question & Answer

Re: CQD answer published August 9 & August 21, 2018 - Service Equipment 3 Discussion on a main disconnect located at a remote pedestal feeding a home. Your answer was that the service is at the pedestal and a feeder would then supply the home and a 4 wire feeder circuit would be needed. My question how we ground this after we install the bonding jumper. There is no concrete encased ground at the pedestal. So does this then not need a concrete encased ground? Also the interconnect bonding bar needs to be installed at the service location. There will be very little use for those bonding bar at a remote pedestal. I'm not sure that a run of a fifth wire back to the home to make these connections could create a situation of a potential difference between the ground and the service. Curious what you think. Rod Christmann
View Question & Answer

Re: CQD answer published Thursday, August 16, 2018 -Bathroom Circuits/Receptacles 1) No, Paul H 2) Congratulations, you have failed to answer the question. The 2017 NFPA 70 does not prohibit additional receptacles to be installed on additional 15 amp 120 volt circuits provided there is a receptacle fed from a 20 amp bathroom receptacle circuit in the bathroom. Class A GFCI protection is still mandated. Cordially, Bill Nolte, C.S.H.O. 3) I don't believe that answers Barry's question on whether ALL receptacles must be 20A in the bathroom or can you have 15A receptacles in the bathroom. Jeff Bower 4) Hi Charlie: This is a good question and in all fairness, I don’t think it was answered fully. Barry states that he has met all the code requirements as you state but I don’t think that is the question. The question I believe is for an additional 15A circuit in a bathroom with devices like lighting receptacles. I can see Barry’s concern as today we are seeing much larger bathrooms (per code definition IE contained Basin & toilet) that include maybe a large dressing area or larger floor storage area. My next door neighbor has a bathroom larger than her bedrooms. I think the problem is with the wording ”At least one 20 ampere branch circuit”. It doesn’t say “No other circuits”! and I think that’s what Barry is asking. As a further example and to really muck things up we could add laundry equipment to the bathroom which is also becoming a norm. Perhaps we need a whole new room definition (LaundBath) with all new rules? My question: Does anyone know the logic behind the 20A, GFCI, 3 foot to basin article? I always assumed (bad to assume) it was because of high draw devices like a hairdryer. My wife blows that theory to bits by drying her hair in a bedroom so why do I need a separate circuit in the bath and not the bedroom with similar rules? Thanks, John Richardson 5) The answer published on August 16, 2018 did not address the question. The issue raised was whether a second bathroom receptacle in a dwelling unit can be supplied by a 15 amp circuit, if you have already complied with the requirement to install “at least one” 20 amp circuit to “supply the bathroom(s) receptacle outlet(s).” The answer did not address the “15 amp circuit.” My answer would be that the code is not as clear as one could wish, as it does not explicitly state that ALL bathroom receptacles must be fed by 20 amp circuits. But I believe we can infer, from the existing wording, that that is the requirement. It says to provide at least one 20 amp circuit to supply THE bathroom receptacles. It would have been clearer if it said “ALL THE.” But it also does not say “the REQUIRED” outlets. If it had, that would have opened the door to allowing the "not required, extra" receptacles to be fed from a 15 amp circuit. Regards, Charlie Beck
View Question & Answer

Our electrical room is 1200 amp service. The architect wants to depress the floor so this will have steps. Doesn't this have to been level service to exit? Mike Conley
View Question & Answer

Re: CQD answer published Tuesday, August 14, 2018 - Feeder and Service Neutral Size Charlie, I very much enjoy the CQD and start each of my days with reading the questions and answers. This is a very valuable forum for the industry. Regarding the answer provided for the sizing of the neutral for dwelling services, the 2017 NEC does not allow the reduced neutral to be used for single phase 208/120 volt services or feeders from a 208/120 three-phase system. Small nuance in the text that has to be read carefully. 310.15(B)(7)(1) to (4) applies for 240/120 volt services, but only 310.15(B)(7)(1) to (3) apply to 208/120 volt services. The list item 4 is where the neutral is allowed to be reduced. Keep up the good work, Chuck Mello
View Question & Answer

Re: CQD answer published Monday, August 13, 2018-Grounded Conductor Terminations 2 Grounded vs. grounding conductors.......... When is the NEC going to be written so it can be understood? 408.21 is a good example of how not to write the code. The attachment from Siemens recognized the problem and reverted to "neutral" and "ground" to explain the requirement. https://w3.usa.siemens.com/us/internet-dms/btlv/Residential/Residential-Murray/docs/Grounded_Conductor_Terminations.pdf Dave
View Question & Answer

Re: CQD answer published Wednesday, August 10, 2018 - Temporary Feeder 2 Aerial cable such as Triplex, is not listed or labeled by a National Recognized Testing Laboratory (NRTL). It may be used up to the service drop since the NEC does not incorporate that part of the service system owned by the utility. From there on, Listed material must be used unless specifically allowed or sanctioned by other means. I've heard of Four-Plex cable that allows for the insulated neutral wire (grounded conductor) to be carried with the messenger cable, normally used for the grounding conductor. However, I've yet to come across this method of wiring being described in the NEC for use. Best Regards, Nick Abbatiello
View Question & Answer

Re: CQD answer published Thursday, August 9, 2018 -Service Equipment In response to the new question for Wed August 8th. I have always assumed that if there is a main disconnect, then any service wires on the load side of that disconnect are to be considered a feeder. Then also the main grounding must occur at the service disconnect and not anywhere downstream of that disconnect. If I read the question correctly, then there is a main disconnect/ overcurrent protection at the meter pedestal he is talking about in his question. Therefore I would agree with him that a ground neutral and two hot wires are going to the home from the main at the pedestal. I do not see how it can be done any other way unless the ahj has said that the wiring to the home from the pedestal can be considered as though they were a service drop to the home. Kenneth Lynes
View Question & Answer

Does a 24v connection have to in a box Steve Farrington
View Question & Answer

I have a job at the NIH facility in Bethesda Maryland that I need to run a nitrogen line to a room being remodeled. We want to run the nitrogen line through an electrical room. The nitrogen line would run over several electrical panels. Can I run the nitrogen line over the electrical panels, Is this acceptable with the NEC codes? Nitrogen is non combustible in fact it takes the air away from a fire should a fire start in the electrical panel. I would appreciate your response to this question, Thanks for your time. If the nitrogen line can run in the electrical room code you please provide me with a code number. Walt Ugolick
View Question & Answer

Re 210.11 bathroom receptacles. In addition to the required 20a receptacle(s) within 3' of the sink, can other receptacles be installed on 15a circuits? Barry J Yeslow
View Question & Answer

Re: CQD answer published Tuesday, August 7, 2018 - Instead of using THHN conductors (I just assumed that since very popular), use a Machine Tool (MT) conductor with similar electrical properties but with finer strands of softer, or annealed, copper. The THHN and standard types of conductors are not designed for continuous flexing or significant vibratory motion because of stiffness. Machine tool wiring is designed for such applications. If that's not desired, a short length of outdoor rated type S flexible cord could be used. Type SWO comes to mind, but there are many others that even have better environmental ratings. Best Regards, Nick Abbatiello
View Question & Answer

Best resource available. Does the NEC allow a reduced neutral for a balanced 3 phase load? I was told this has been changed, where? Thanks, Have a good day!! Lowell I. (Laddie) Wolfe Jr.
View Question & Answer

Re: CQD answer published Wednesday, August 1, 2018 -Grounded Conductor Terminations If a terminal bar is listed and identified for multiple conductors why can't more that one grounded conductor be connected that way? Am I reading Section 408.41 wrong? Thank you for your response, Christine
View Question & Answer

Is acceptable a TEMPORARY 120lnft AC feeder (4-2/0 & 1-#4 gnd) running through plenum area without conduit? Also, a 150lnftDC 2/0 feeder running in the same way? Rafael Colon
View Question & Answer