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An inspector took the following photograph of a residential home’s circuit breaker panel.

enter image description here

White wires are connected to the neutral bar. Black wires are connected to the circuit breakers in the picture, but there’s one white wire among them. Why would it be wired in such a way (rather than a black and red wires alternating)?

Note: The circuit breaker panel is not labeled.

A pic from Google images of a circuit breaker panel:

enter image description here

  • My (un)educated guess is that you have a white wire being used as hot (its connected to a phase through a breaker) but it hasn't been marked as such. Wrap some black tape around it (at both ends of the cable). – brhans Jul 26 '16 at 19:03
  • Brhans, In home wiring everything is single phase L1 & L2. Many people think they are different phases but they are from the same leg of the supply (center tapped single phase) is the configuration of the transformer supplying 99% of all U.S. homes. – Ed Beal Jul 26 '16 at 19:19
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The white wire is being used as an ungrounded (hot) conductor, though it has not been properly marked as such. Looks like a fairly large wire, so it's surely feeding a larger 240 volt load. The breaker that it's terminated at, should be a double pole breaker, and is likely rated 50 amperes (check handle label for rating).

The load being supplied by this circuit will require 240 volts only, so a grounded (neutral) conductor will not be required. Because of this, the circuit will be wired with a two conductor (plus ground) cable. Two conductor cables are manufactured with a black, white, and bare (or green) conductor inside. When using this type of cable for 240 volt circuits, the white wire can be used as a hot conductor. According to National Electrical Code, the white wire should be marked to indicate this repurposing.

  • Well I guess I should start waiting to answer questions as I did answer this and then your answer later the same as mine but I edited to say no it was not code this has happened many times so I guess trying to help folks quickly has no merit Imo. P.S. A water heater is one of the few 240 loads that requires no neutral. – Ed Beal Jul 27 '16 at 1:06
  • @EdBeal Sorry if you feel slighted in some way. I often answer from my mobile phone, and so am not always looking at the most recent data. When I started writing my post, this question did not appear to have an answer. – Tester101 Jul 27 '16 at 10:31
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This happens because of the common color codes for multi-wire cables. xx/2 cable is Black, White, and Bare. xx/3 cable is Black, Red, White and Bare.

A 240V (only) load like a water heater only needs 2 conductors. So they use the /2 cable, which is Black, White and Bare.

However they are both "hot", so white is the incorrect color. The rules require this be "marked" with colored tape or paint. But previously, the marking wasn't necessary if the use was plainly obvious. Heavy wire makes it plainly obvious that this is a high-current circuit which is almost certainly 240V, and the 2-pole breaker confirms it.

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    Do you happen to know at which code revision (year) "previously" changed to "now"? That would improve the answer. At this end it's incredibly obvious (it's connected to a breaker) and if it passes without junctions to a 240V device the connection at that end would also be fairly obvious. I prefer having them marked, but I know from experience that it's quite common for them not to be. – Ecnerwal Jul 27 '16 at 3:19
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    I don't follow code that closely, and I suspect local variances may be common in this area, either in ordinance, or in practice. – Harper Jul 27 '16 at 3:45
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The answer is No. brhans, guess is correct. Many water heaters are wired this way because there are no neutral's in a standard 240V water heater. The white wire needs at least 6" of other than white or green identification some inspectors want everything in the box identified (taped or painted). Black is the most common color using tape but, it can be painted also I found red fingernail polish and this is totally legal also. Added for history: The oldest code book I have handy is NEC 2002. Section 200.6 & 200.7 both identify the grounding conductor as white / gray or white / gray stripe along entire length. 310.12.C states ungrounded conductors shall be finished to be clearly distinguishable from grounded and grounding conductors. So this has been code for quite some time.

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