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So, we have a circuit that runs from the panel to junction box A, then to junction box B, and then onwards to a load. Can the fixed Chapter 3 wiring between junction box A and B be replaced by a flexible cord "pigtail" emanating from junction box B and plugged into a single receptacle in junction box A, to provide for the interchange of the equipment providing the power source to the circuit? (Say, to a generator if this configuration was mounted outdoors and made of outdoor-rated parts, or to an inverter powered by some DC source, or even simply to a different circuit for some bizarro reason.)

It seems to me that while this isn't quite the situation in 400.7(A)(11) as this is field fabricated -- 400.7(A)(6) would hold, as we are connecting some load to facilitate interchange -- just not of the load, but the source powering the load. Or does 400.7(A)(6) not apply, rendering this arrangement a 400.8 violation as it'd be substituting for permanent wiring?

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  • Sounds like an interpretation issue (without being privy to the actual code you are referencing). Would it be viable to just get your best code officials opinion that you know or try to find the right official on the right day and have a carefully navigated site visit? I know for something of the magnitude you are talking we would just navigate carefully through the code official on their interpretation. We've had code officials make us do some weird stuff to make them happy, but we got the function in the end after carefully not giving up after they initially said "noway"
    – Damon
    Jan 5, 2016 at 6:31
  • So basically you're going to use the cord to switch between utility and generator power? Sounds like you should be using some type of transfer equipment instead.
    – Tester101
    Jan 5, 2016 at 13:55
  • If part of the objective is to be able to trivially and safely remove the transfer equipment then a cord or better yet a male "generator receptacle" would be a simple answer. I don't think its very classy for flexible 'pigtails to be emanating' from fixed equipment. Just don't think about overhead power drops in server rooms, or under-floor conduited jboxes in there either, or window air conditioners, or garage door openers, or sump pumps. Jan 5, 2016 at 19:09
  • @Tester101 and billycrook -- The idea here is that the cord and plug pigtail is the transfer equipment Jan 6, 2016 at 0:07
  • Interesting question. I've been tempted to do this to tap an existing 30A dryer outlet to feed other outlets for my workshop. A better answer is to rewire, dropping a splice or (better) a secondary box in place of the old outlet, but I was sorta thinking that by making it officially temporary wiring I might dodge the need to get it inspected. That isn't a good reason...
    – keshlam
    Dec 3, 2016 at 17:07

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In my area the inspectors require 156% wire size (125% x 125%) if a flexible cord is used as a non permanent connection. Something like a portable generator. The other requirement is it needs to be 30amp or less. With that said there is usually a transfer switch to the specific circuits being powered. Larger supplies are required to be in 6’ or less liquid tight. All parts must be listed for the use or type of power generated (like Solar, motor driven generator). Some inspectors are easy some are real buggers. I have set a couple dozen of these up over the years and the biggest hassle is proving the grounding to show if it is a separately derived system. (I mentioned Solar since the comment about DC). Just another note the 156% wire size is on fabricated cords not the ones that come with the transfer switch that are molded.

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    156% on flexible cords??? What is their justification for this absurd code? Jan 5, 2016 at 15:07
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    They get it from the solar requirement and "fabricated" wiring to make sure the ampacity of the cord is sufficent. If a listed molded cord is used 100% works. I just looked it up 690.8.A info note for the solar. Since Flexable cords are not normaly allowed I am ok with meeting the rules they set. Most customers want a portable but cannot or do not want to put the generator within 6' of the house so then a feild made unit with extra hard ussage cord 8 awg has been allowed.
    – Ed Beal
    Jan 5, 2016 at 15:19

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