Do all RCD trip with a power outage?

[mfarrow]

As so often, it's clearly a case of swings and roundabouts, but would it really be that dangerous for you to find your way to a light switch in the dark?

You (or should I say, somebody) would have to undertake a weighted risk assessment looking at the likelihood of someone using a latched-on dangerous machine when the power goes off against the severity of injury they might get. Compare this to getting up to put the lights on. The likelihood of the latter is a lot greater, but how that weighs against the severity of injury, I wouldn't like to guess. It's certainly not very convenient to have to get up and turn the lights on after a black or brown-out, and then find the consumer unit to get the power restored.

Other things you'll need to have on a passive RCD include items you wouldn't want to permanently lose power to in winter if/or you went away on holiday, so: boiler, immersion heater, storage heaters, fish tank filter/aerator, PVR, burglar alarm.

 

[bernardgreen]

During the winter of discontent when power cuts were regular it was common to fit latching contactors to control supply to work benches and similar hazardous places. The contactor dropped when the power cut occurred and then had to to be manually re-latched after the power cut ended.

I came across some benches where the manual re-latching was a pencil used to press the contactor's armature down. that is NOT an approved method

 

[JohnW2]

As so often, it's clearly a case of swings and roundabouts, but would it really be that dangerous for you to find your way to a light switch in the dark?

You (or should I say, somebody) would have to undertake a weighted risk assessment looking at the likelihood of someone using a latched-on dangerous machine when the power goes off against the severity of injury they might get. Compare this to getting up to put the lights on. The likelihood of the latter is a lot greater, but how that weighs against the severity of injury, I wouldn't like to guess.

Exactly. Although your version is much longer than mine, we seem to be saying essentially the same thing ('swings and roundabouts'). As you say, actually deciding which of the two 'wins' in risk-assessment terms is anyone's guess - I doubt that one would ever be able to get enough reasonable data to make a reasonable assessment.

In terms of specifics, FWIW, I would have thought (without data!) that the risk of sustaining a significant inury whilst finding the light switch in the room one was in would be extremely small - one would, after all, be 'very careful' when moving about in the dark. Furthermore, the risk of that scenario arising at all would be very small since, unlike yours, very few households will have no 'lighting circuit lighting' switched on when it is dark.

As you will be aware, all I said in response to BAS's suggestion about active RCDs was "One could certainly argue that", and I am in no way 'promoting' the idea. Individual 'no volt protection' of items of potentially dangerous equipment is clearly a better-targeted way to go, that would produce virtually no 'nuisance' and would add few risks that I can think of.

Kind Regards, John