National Electrical Installation Standards

Is it permitted to run Ethernet (100BT) and twisted pair telephone signal in an eight wire Ethernet cable? Mike Clott
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Re: CQD answer published Friday, May 11, 2018 - Incomplete answer. The governing body of the facility first must define the room usages on site, hospital, Limited care or nursing care. Only the governing body has authority to do this not the Inspector, then can the level of care is determined, the proper type of required receptacles can be determined. Question. In exam rooms what level of car is given, and who set that? Bill Schell
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In a new RV park where we have power pedestals with receptacles for RV's to plug in, My understanding of Art 551 is that grounding is accomplished with a grounding conductor with the feeder conductors. And, the grounded and grounding conductors are not bonded at each pedestal. Am I correct? Ronald Chiaratti
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I'm currently a student in the F.E.A.T. school in Florida and I notice there are a ton of mentions to "subject to physical damage" or "severe physical damage". I have asked my teachers and my boss if it's defined anywhere what physical damage covers. The only answer I've gotten that makes sense is thru my boss stating that the determination of what physical damage is, is left to the AHJ that runs the area. My question is just if there is a detention anywhere for what all is subject to physical damage or is it like my boss stated it is just up to the AHJ? I was curious is there was another book that might state it or not. Thank you for your time and hopefully hear from you soon Devon Prest
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Hey Charlie, I have a continuous duty motor that I am feeding from a VFD. The VFD is fused at 60 amps and is fed from a 480 volt panel. I used NEC table 430.250 for the FLA and for a 20 HP motor it has a 27 IFLA. My drawing shows a 60 amp breaker (instantaneous trip) feeding the VFD with # 8 AWG THHN. I know you can oversize your breaker for motors, but where in the NEC does it show that #8 is good for a 60 amp breaker. According to 310.15 (B) (16) , #8 is only good for 55 amps. Thanks for your help, Michael from New Mexico
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Re: CQD answer published Thursday, May 3, 2018 -Service Calculations 1) Actually, I believe the electrical contractor is responsible for the design and load calculations of the electrical system. The inspectors role is to review, inspect and verify the work is compliant to adopted code edition. If the inspector is involved on an existing system, pending contractors submittal, he may offer recommendations of upgrade; but he is not the designer or professional to design or it set forth the specs. That should be the role of contractors and/ or design professionals in consultation with the client's needs. RE Miller 2) Thanks for the service you provide. This is in response to question Jeff posed on 02/05. The inspectors rarely look at the required calculations. They are there to look at the physical installation. The review of the technical/design details is done by the people that review the plans and issue the permits. Unless it is a small jurisdiction, these tasks are seldom accomplished by one individual. Keep up the good work. Mike, Columbus, OH
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Under table 300.50 - it does not clearly specify (in column 2) if those conduit depth requirements are for direct buried or concrete encased. We have a situation at JFK airport where we are struggling to meet the 18" depth for concrete encasement for runway and taxiway lighting installation (voltage between 1kv and 22kv). Also, in lieu of RGS (for 6" depth), is it compliant to use LFMC - concrete encase? Al Volpe
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Changing 200 amp panel located 7’ from the meter base, requires an exterior safety switch. The new panel is a main breaker, does the safety switch have to fused or can it be non fused? Pete McCarthy
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Re: CQD answer published Monday, May 14, 2018 -Support vs Secure In regards to your answer for Friday, May 11, 2018 concerning securing and supporting of Type MC cable, I would like to quote the great Phil Simmons. Phil would say it’s like riding in a car. The seat supports you, but the seat belt secures you in the car. The framing members are the car seat, and a listed strap is the seat belt. Regards, L. Keith Lofland
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Re: CQD answer published May, May 8, 2018 - Termination Fastening I would be far more concerned about utilizing a pressure (Bellville type) washer than I would be about the 1/2 inch vs 3/8 inch bolt. The Grade rating of the bolt/nut is also critical - Grade 5 (three lines on the head) is nearly twice that of "standard" bolts, and Grade 8 (six lines) is near three times as strong. These terminations are subject to significant thermal cycling, and the added spring force provided by the special spring washer can be critical in maintaining solid contact as the various metals expand and contract. As to the 1/2 inch vs 3/8 inch bolt question - a high quality 3/8 inch bolting is capable of providing several thousand pounds of compression force to the joint. A manufacturer might very well make the lug with a 1/2 inch hole to provide its ability to be used in various applications. Even a 1/4 inch bolt can provide large rated compression (tensile strength) : Grade 5 = 4,000 lbs, Grade 8 = 5,000. 3/8 inch Grade 5 = 9,800, Grade 8 = 12,000. I would be astounded to hear from a lug manufacturer (or U.L.) that a 3/8 inch bolting was not capable of providing adequate compression. Thanks for the great forum of discussion. Scott Cline
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The CQD question and answer was not published on Wednesday May 16, 2018 so we are trying again. NEC 2017 Article 210.8 (A)(7) Interpretation, Charlie- Dwelling Unit Questions: 1). We have a wall hung microwave located directly above a sink where the distance between countertop and bottom of microwave is 18”, and the receptacle for the microwave is located in the cabinet above. Does this receptacle require GFCI protection if the microwave cord passes through a fixed barrier? 2). Do the receptacles for the garbage disposal, dishwasher, and beverage cooler below the countertop require GFCI protection? Joe Koss
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The CQD answer was not published on Tuesday May 15, 2018 so we are trying again. Good Morning, We are currently wiring several new Hospitals that were permitted in 2016 when the 2014 NEC was in effect. Because these buildings are taller than 75 feet we have made sure to have the feeders for the life safety panels protected by either sprinklers or 2hr rated chase, But in some areas this was not feasible so we elected to run 2hr fire rated Draka cable to those Panels. I recently noticed in 6.4.2.2.1.6(B) 2015 NFPA 99 that fire protection of emergency feeders in 700.10(D)1-3 does not apply to Hospitals. Which code overrules which, 2014 NFPA 70 or 2015 NFPA 99? Secondly, we are starting another Hospital where the 2017 NFPA 70 & 2015 NFPA 99 are in effect. In the 2017 NEC It specifically states that Healthcare Facilities where persons are not capable of self-preservation are to have the fire Protection of Life Safety feeders. Which is still in direct conflict with the 2015 NFPA 99. Which code prevails? Thanks, Kelly Wofford
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Good morning, and thanks for keeping this forum going. Simply put, may a 100amp main lug sub-panel be fed from a 60amp breaker at the main panel ? Thanks, Steve from Jersey.
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Good morning, According to my understanding in the code book… A 220 outlet for a car charger that’s mounted outside does not to be need to be GFI protected...is that correct? Thanks, Alex Hristo
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When doing a rewire in a dwelling of an existing AC or heating unit if there is no outlet within 25’ are you required to provide one David Pedroli
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