Fatal Incident - Safe Isolation failure?

“Consider the theoretical situation where the isolating device somehow disconnected N and PE but left L connected…”

I had a job that I posted a topic about a few years ago, some electricians had installed storage batteries to a TT earthed installation with solar panels, a hot tub and a ham radio station, nothing like keeping it simple, after they had installed the batteries RCDs kept tripping, which was what I was trying to sort out.

Completely unrelate to the actual problem I discovered they had installed a four pole isolation switch which was supposed to turn off the mains and on-site supplies simultaneously, but they had actually miswired  it  so that the live conductor to the main house was disconnected, but the neutral became live Including the bare metal neutral bar in the consumer unit. So if you used this upfront isolation switch the consumer unit rather than the main switch within the consumer unit the CU became a very dangerous  place to be working. This could be detected using a simple plug in socket tester, voltage testing device or an installation tester, but you do have to be checking.

Treating every electrical installation as if it was installed by an idiot is the starting point for safe isolation, the second being treat everything as if it is live and you need to wave the volt stick about a lot, but don’t rely solely on the volt stick.

After watching the safe isolation on YouTube I mentioned above, but could not find I bought a Martindale VT7 single pole contact tester, bearing in mind my Fluke T150 does a single pole contact test as well so now I have two ways of doing this test, the Martindale VT7 should indicate if a metal enclosure or similar is live, but I don’t have enough experience of using it to make a recommendation.

“Consider the theoretical situation where the isolating device somehow disconnected N and PE but left L connected…”

I had a job that I posted a topic about a few years ago, some electricians had installed storage batteries to a TT earthed installation with solar panels, a hot tub and a ham radio station, nothing like keeping it simple, after they had installed the batteries RCDs kept tripping, which was what I was trying to sort out.

Completely unrelate to the actual problem I discovered they had installed a four pole isolation switch which was supposed to turn off the mains and on-site supplies simultaneously, but they had actually miswired  it  so that the live conductor to the main house was disconnected, but the neutral became live Including the bare metal neutral bar in the consumer unit. So if you used this upfront isolation switch the consumer unit rather than the main switch within the consumer unit the CU became a very dangerous  place to be working. This could be detected using a simple plug in socket tester, voltage testing device or an installation tester, but you do have to be checking.

Treating every electrical installation as if it was installed by an idiot is the starting point for safe isolation, the second being treat everything as if it is live and you need to wave the volt stick about a lot, but don’t rely solely on the volt stick.

After watching the safe isolation on YouTube I mentioned above, but could not find I bought a Martindale VT7 single pole contact tester, bearing in mind my Fluke T150 does a single pole contact test as well so now I have two ways of doing this test, the Martindale VT7 should indicate if a metal enclosure or similar is live, but I don’t have enough experience of using it to make a recommendation.