I'm a but puzzled by the electrical panel in the attached picture and trying to guess/figure out what is going on. If relevant, this is in France.

The issue is with two breakers in the red box in the picture. The two issues:

  • The left one appears to be have a phase output only, and is missing the neutral output (yellow circle).
  • The two breakers appear to be somehow connected to the same wall outlets. Opening either breaker cuts the voltage on the outlets.

The cables all go into the wall and are not easy to follow. Can anyone guess what is going on, or how to test that? Could there be any hazard associated with this installation? These power outlets are the kitchen (oven, washing machine, dishwasher supposedly, though I doubt all could run at the same time on a 20 or even 16 amps breaker).

electrical board output

The input of the breakers looks normal, cf. picture below.

electrical board input


  • This is a single phase system.
  • The colors of the cables are clearly not respecting code standards.
  • This is in a rented apartment. Regulation does not impose the electrical installation to respect the current code, but it does require it to be safe. Here, the 30mA differential breaker is generally considered "good enough" to limit the risk of electrical shock. So the remaining issue is fire hazard, which seems to be the main problem here since the wire does not appear to be sized for the 16+20=36 amps allowed by the breakers.
  • Full panel picture added for clarity (with a few more oddities...)

full panel

  • In North America it looks like a multi wire circuit, two circuits but share the neutral to save wire/copper. It seems to be a red wire for neutral, which might be a big no-no in France. Top and bottom of a dual outlet can have different breakers so two high power devices can be plug in at the same time, can also be one outlet and the next one on different breakers. If this is allowed in France, I don't know, a local electrician will. Both breakers must be off for safe work done on outlets/circuit.
    – crip659
    Commented Apr 22, 2022 at 12:55
  • Please revise your post title to ask a clear, specific question.
    – isherwood
    Commented Apr 22, 2022 at 14:04
  • All that red wire hurts my eyes. I haven’t been to France but the countries over the pond I did visit had wire color code standards. There toners that you can turn the breaker off and inject a tone then go find where the wire goes. I don’t think it could be a multi wire as the breakers are different sizes but maybe they were blinded with all the red wire.
    – Ed Beal
    Commented Apr 22, 2022 at 15:14
  • I wonder if the yellow/green striped electrical tape indicates that those particular red wires are supposed to be grounds.
    – FreeMan
    Commented Apr 22, 2022 at 15:41
  • @FreeMan that is ground color, but no. That is groupings. That is indicating the wires are a multi-wire branch circuit. (yeah, those exist in 3-phase, extra cool actually). Commented Apr 22, 2022 at 17:55

1 Answer 1


That is not ok.

  1. The neutral wire from the second breaker ought to be blue. This is "just" a code violation, altough a severe one and an indication of shoddy workmanship and further issues.
  2. There are two phase conductors, secured by two breakers and one neutral.

The current from the single phase (those without neutral) has to return somewhere. Since there isn't a dedicated neutral, someone took the neutral from another circuit.

It means that, in worst case, the neutral has to carry more current than it supports and overheats, possibly setting something on fire.

No, your breakers do not secure you against overcurrent through the neutral. They control (open and close) both conductors, but the current and thermal sensing is only on the phase.

A shared neutral between two breakers is definitely not ok

  1. The neutral? wires at the bottom, who are bonded together with an non-insulated bar. That isn't ok for an TT earthing system.

Update: On a second look, those wires aren't blue. They look more like black. It could be that the black wires are the ground conductors in your house. Black is a color reserved for the "phase" (hot) and definitely not the right choice for the ground.

  1. The wires connected together by the green-yellow tape: Relatively to the severity of the other points it is a minor error. Green-yellow is reserved exclusively for the grounding conductors.

For more clarity please attach a larger photo of the entire panel.

Why does both breakers affect the outlets?

That is simple: The outleds receive the phase from the first breaker, and "return" the current through the neutral of the second one. Opening one of the breakers will "cut" the outlets, either by cutting the phase conductor or the neutral. "Neutral only switching" isn't ok for fixed installation, since the conductor is still under tension.

  • You shouldn't have a shared neutral across two breakers on a TN earthing system either. Turning off one breaker can leave the neutral live.
    – Simon B
    Commented Apr 22, 2022 at 17:49
  • Thanks for the answer. 1: yes. 2: thanks, that's what I was looking for. 3: right, black is ground here, apparently this used to be the code here at some point (now green+yellow). 4: yes.
    – Colas
    Commented Apr 23, 2022 at 9:40

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