Live/Neutral Reversed Main Outlet


Note: This post is talking about UK (220-240V mains supply)

My girlfriend and I recently moved into our newly-purchased house. We wanted to get the electric meter changed but when the guy came out to do so, he reported a live reading on the neutral block in our meter box. This was potentially dangerous, he said, and he called out the mains engineers. They investigated and couldn't replicate the problem. They asked if we'd experienced any problems in the house and we hadn't.

Since then we've had three occurrences of the RCDs in our fuse box tripping. I today bought a standard socket tester and tested every socket in the house. I've found the culprit to be the mains outlet in our spare bedroom, which appears to be incorrectly wired, showing a live/neutral reverse on the tester.

My questions, then...

1) Would this explain both the apparent live neutral reading in our main meter box and the tripping of the RCDs? I always thought RCDs were only concerned with earthing faults, not live/neutral reverse polarity type problems

2) I've been using the sockets in that room with no real probles apart from the trips. All equipment (TV, XBox, amplifier, phone charger) have worked OK thus far. Is the socket likely to be causing any harm?

3) Is this potentially dangerous?

4) Is getting this fixed a big (and ergo, expensive) job?

Your help would be much appreciated as I've had surprising difficult finding any info about this on the web.

Many thanks


Reply to
Andrew Thelwell
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No, this may simply have been an error on the part of whoever was raising the problem, or a polarity problem was found externally, corrected and covered up.

The RCD senses the live and neutral currents in and out, the reversed polarity would not be detected.

These units would all operate OK with reversed polarity.

Yes, e.g. say an open element fire were plugged in to that socket, the element would remain live even when the heater were switched off, since the live wire is not being switched.

Not expensive, simply a case of swopping the live and neutral at that socket, after having firstly isolated the circuit at the source DB; or Fuseboard.

You mention RCD's in plural, do you have two of these or were you referring to MCB's?

As you have recently moved into the house, it may be the case, that there is a leaky appliance which is causing the tripping. An In Service Inspection and Test, (the former PAT) would probably isolate the faulty unit. An insulation test and a test on the RCD could also be done. I personally moved into a house with modern MCB's etc., from a house with a Fuseboard. I had to bin an electric grill and iron because of trips on the RCD.


Reply to
John McLean


I referred to RCDs, in fact on our consumer unit they are referred to as "Earth Leakage Circuit Breakers". Perhaps I have used the wrong term (but I thought it's the same thing?)... There are two -- apparently one on each of the two main loops in our house. They trip at 30mA and are big grey rotary type switches -- quite old-fashioned looking but clearly doing their job I guess!?



John McLean wrote:

Reply to
Andrew Thelwell

Vice it

Reply to
Dr. Bizarro

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