National Electrical Installation Standards

Standards as High as Your Own

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  • August 29, 2017

    Re: CQD answer published Tuesday, August 22, 2017 -Services and Generators Good Morning, in regards to Monday’s 8-21-17 Code Question, I see now I did not word the question correctly. The Utility Transformer feeds the Service Main Distribution Board (MDP). MDP then feeds normal power to a 4P ATS and the Generator feeds emergency power to the 4P ATS. The MDP gets a Main bonding Jumper and since the ATS is a 4 Pole, then the Generator (Separately Derived System) requires a System Bonding Jumper. Done. But then It get confusing. The Utility Xfmr. also feeds the Fire Pump Controller (3 Pole ATS) for normal power. The generator supplies an emergency feed to the F.P Controller (3P-ATS), apparently they do not make 4 Pole Fire Pump Controller ATS’s since the F.P. motors are 3 Phase 480 volt and a neutral is not needed. Question 1. Since 250.24(C) requires us to bring the grounded conductor (neutral) to all Service Disconnecting means. I now have a generator that feeds a 4 pole ATS via MDP and a 3 pole F.P/ Controller ATS. Since 1 ATS is 4 pole with switched neutrals and one is 3 pole with Norm. & Emergency neutrals bonded together. Wouldn’t that be a violation of 250.30(A) Question 2. If I did not have to bring a neutral from the Utility Xfmr. & from the generator to the 3P Fire Pump Controller ATS that would solve my dilemma. Is there something in the code that would allow me to do that and not violate 250.24(C) ? Thanks in advance for your help, Kelly Wofford
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  • August 28, 2017

    I understand the requirements of 445.11 for generator marking. However, if my generator is 34KW the rated output in amps would be 147 Amps if the single phase generator voltage output is 230VAC @ 60Hz. Is this a correct statement? Or would it be the total of each 115 VAC leg fused at 125 Amps each therefore the amp rating would be 250Amps? Trying to figure out the required rating that needs to be on the nameplate. Amy assistance will be greatly appreciated. Clay Hulsey
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  • August 25, 2017

    How do you size a subpanel off of a 100 or 200 amp panel. What is the largest size I can run. Thank you, Dave
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  • August 24, 2017

    Charlie, My question is what is one to do if due to unforeseen soil conditions such as buried rocks or just hardness of the soil what can be done if I cannot get these grounding rods down the entire 8 ft.? And this has happened to both rods I tried to put in at the same location. Dan Wheeler
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  • August 23, 2017

    Re: CQD answer published Monday, August 14, 2017 - As per code section , an individual branch circuit is only required if cord is used, not when direct wired for range hoods Tom Couch
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  • August 22, 2017

    If a house was built in 1964 with a 2-wire system, and the kitchen is remodeled to have GFI outlets, how are the new outlets to be grounded? Can a ground wire be daisy chained to each GFI and connected to a galvanized water pipe? Or does the ground wire have to go to the panel and to the ground rod? Will the breaker panel have to be upgraded necessarily? Rick Hadley
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  • August 21, 2017

    Good Morning, We have an Assisted Living Facility that is fed from a Utility transformer and a Generator back-up. We have the service Equipment fed through a 4 pole ATS from both sources of power. The MDP (Service Equip.) has a Main Bonding jumper and the Generator has a System Bonding Jumper because the neutrals are being switched at the 4 pole ATS. Question is at the second service for the Fire Pump is fed from the Utility transformer and Generator via the Fire Pump’s 3 Pole ATS where the neutrals are Landed on a common bus. It seems to me, like it really should be a 4 pole ATS in the F.P. Controller otherwise how do I determine whether the Generator is a separately Derived system or not? Thanks, Kelly Wofford
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  • August 18, 2017

    High Rise Hotel -Typical Electrical Room - Vertical Feeder Bus duct. We have (2) 2 section panels in the room. Both are fed from the vertical bus duct. This will require 2 bus plugs on the same bus duct. Is there a min / max mounting height requirement to mount these bus plugs. Dale Daniels
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  • August 17, 2017

    Charlie, I really appreciate most of the conversations relating to every day code issues. You really do a great job. I have a big box store that has a pharmacy located inside the store. The pharmacy has a receptacle for a blood pressure monitoring machine. Would this monitoring machine require GFCI protection for personnel? Thanks, Allen
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  • August 16, 2017

    Re: CQD answer published Wednesday, August 9, 2017 -GEC ID My Comment….Also taping any GEC green would also be in violation the NEC, correct? Thanks, Alan Chech
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  • August 15, 2017

    Can you put a panel box in the kitchen? Tony Blevins
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  • August 14, 2017

    Re: CQD answer published Tuesday, August 8, 2017 -Box Covers If the electrical box is in a ceiling that is required to be fire rated, inter-national building code section 724.4.2 applies. Electrical boxes are included in an exception that allows membrane penetrations under conditions stated in the exception. Although the exception does not specifically require covers for metal boxes, inspectors may require covers if they judge that is the intent of the code. Non-metallic boxes shall be installed as tested under the fire rated listing, which may require covers. David Green
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  • August 11, 2017

    My question is about 422.16B4(5) referring to an individual branch circuit. Is this because an outlet installed for a range exhaust fan could in the future be used for a microwave/fan combo? Thank you, Julia Sinclair
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  • August 10, 2017

    When adding low voltage transformers in the space, we have always been told the secondary had to be 100VA or less or the secondary had to be in conduit. Is this true and where would we find it in the book? Roy Benson
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  • August 9, 2017

    Re: CQD answer published Tuesday, July 25, 2017 -Bundled Conductor Ampacities Grouping / Zip-Tying conductors together inside a panelboard There is a place in the National Electrical Code where one can find rest, peace, and solitude. It is 310.15(A)(2) exception. “Where different ampacities apply to portions of a circuit, the higher ampacity shall be permitted to be used if the total portion(s) of the circuit with the lower ampacity does not exceed the lesser of 3.0m (10ft) of 10 percent of the total circuit.” With this exception, which has been in existence in one form or another for many moons, the portion of the circuit where the conductors are bundled together inside the panelboard are not used to reduce the ampacity of the various circuits. If there was any doubt about this application, the 2017 made its use even more clearly allowed. Can I get an amen?! Matthew Hermanson
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ABOUT CQD: NECA’s Code Question of the Day (CQD) is a leading National Electrical Code® forum for NECA and the industry. The CQD generates a lively dialogue and relative practical and Code-based responses to an ever-increasing and interactive audience.

IMPORTANT NOTICE: All answers are based on the latest edition of the National Electrical Code®, unless the question requests a response based on a specific edition. This correspondence is not a formal interpretation of the NEC®. Any responses expressed to the questions are opinions and do not necessarily represent the official position of NECA, NFPA, or any technical committee. In addition, this correspondence is neither intended, nor should it be relied upon, to provide professional consultation or services.

ABOUT CHARLIE: Charles M. Trout, better known as Charlie, was a nationally known NEC® expert and author. He served on several NEC® technical committees and is past chairman of CMP-12. In 2006 Charlie was awarded the prestigious Coggeshall Award for outstanding contributions to the electrical contracting industry, codes and standards development, and technical training. Charlie was also a member of NECA’s Academy of Electrical Contracting. Charlie’s experienced team of industry experts keep the CQD dialogue and discussions active and informative in the spirit of the man himself, as he wanted.

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