I just changed my heater and it caused the whole wall outlet to go wrong.

The heater was connected to the wall using strip connectors such as this one:

strip connectors

After turning the power off from my main panel, I unplugged these and plugged the new instead but it didn't work when I turned the power on again. So I plugged the old one back and it didn't work anymore either!

I plugged a simple outlet with a lamp and the lamp did not turn on, so I assume there is a problem with my wires. I tried to use Wago instead of the strip connectors with the same result.

Visually, the wires seem precisely the same as when I opened the outlet at first: 4 wires (neutral, live, ground, and pilot) with a section of 2.5mm². My apartment is 15 years old and in good condition, so I don't think there could be a problem inside the wall.

Here is a picture of my main panel (30mA differentials): https://i.stack.imgur.com/rbfdw.jpg. One switch is turned off because I don't know what it is controlling and the other is the switch of my heater so it is turned off while the outlet is left open. When I turn this latte on, nothing happens to the above-mentioned lamp.

I changed a lot of outlets with absolutely no problem before, in this apartment and elsewhere. This problem is absolutely beyond me.

Is there a way I could diagnose this problem without much material?

Disclaimer: I am not an electrician but quite tech-savvy and very cautious. I understand pretty well how electricity works even if I have no official formation. Doing small things like changing an outlet or a heater myself is totally legal here in France, although I would never even touch my main panel.

EDIT: pilot wire.

I just realize that other countries might not have this "pilot" wire in their walls. The pilot wire ("fil pilote") is an additional wire that pertains only to heater outlets. Depending on the frequency of the current in this wire, the heater, if positioned in "pilot" mode, will enter one of the 4 heating modes (off, no-freezing, eco, or comfort). They are usually connected to the main electrical panel so it can connect to a domotic server. In my case, the pilot wire is unplugged, although I plan to install a custom solution on it later.

  • The key is a healthy fear and respect. In the US we have 240V except it's delivered as two 120V phases, with 120V from phase to ground. Industry gets 480V 3-phase power (277V per phase) which is considered quite dangerous. I work with it, but it's not to be treated lightly. Well... European power is actually 400V 3-phase (230V per phase) which is nearly the same stuff! Dec 19, 2020 at 18:51
  • @Harper-ReinstateMonica actually it is 220v at the outlet, not 400v (or maybe in the industry). But may I ask how this relates to my question? Dec 19, 2020 at 18:55
  • I am complimenting you on your carefulness. I am saying Euro phase-neutral voltage is nearly the same as US industrial (scary stuff) phase-neutral voltage. Europe is harmonizing to 230V, may not have done your poletop yet. The 3-phase stuff isn't important. Dec 19, 2020 at 19:28
  • Thanks then :-) Actually, France turned to 230V in 1996, my bad. Dec 19, 2020 at 19:35
  • 1
    ". . . neutral, live, ground, and pilot. . ." What is the "pilot"? Is your heater an electric resistance heater? Is the new heater tripping the breaker on the circuit? Is the breaker a standard breaker a basic overcurrent breaker or is it a residual current (aka ground fault)? Dec 19, 2020 at 20:38

1 Answer 1


After long hours of testing, it happened that the lunatics that made my installation actually switched the live wire and the pilot wire on the main panel's differential.

This is very misleading and seems utterly dangerous as this wire is shared among several outlets. Therefore, despite turning the power off on another outlet, my pilot wire was powered on and could have shocked me!

Healthy fear and respect indeed. Respect for the power of electricity, and fear for the incompetence of others.

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