Electrocuted by roof.

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Scott3

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#270012 19-Apr-2020 17:18

Decided today was a good day to wash the house.

Was up a ladder with a sponge, when I got a fairly hefty electric shock off a piece of roofing steel. Obviously worrying from a safety perspective.

Went back with a multi-meter and measured 236v AC between a nail in the area, and the lawn...

It was raining at the time, and I had already done one lap of the house cleaning out gutters, and was roughly half way around the house the second time with a sponge, so had been blasting water everywhere for most of the day.

Fault has since gone away (down to 7v Ac between nail and lawn).

No breakers tripped. House only has an RCD on the bathroom circuit, and that was not tripped.

Not really sure what to do. Is there any point in calling in a sparky when I can't replicate the fault? Anything they could do to diagnoise.

It may have just been that I got something wet I shouldn't have, and it dried out, but having random bits of the house live isn't a sustainable solution given I have a toddler...

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gregmcc

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#2465714 19-Apr-2020 21:14

CALL AN ELECTRICIAN - THIS IS NOT SOMETHING YOU AS A HOMEOWNER CAN TACKLE

Things that it could be in most likely order

1) A nail/screw holding the roofing iron on has pierced a wire in the ceiling

2) The element in the Hot water cylinder has developed a fault to earth (split in the element) and the earth wire to this has failed, while heating it livens up the roof through the overflow pipe

3) (most unlikely) there has been a reversal on the incoming phase and neutral causing anything connected to earth to become alive

CALL AN ELECTRICIAN - THIS IS NOT SOMETHING YOU AS A HOMEOWNER CAN TACKLE

once it is sorted out, post back here and let us know

Scott3

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#2466635 20-Apr-2020 21:10

Sorry about the use of the term "Electrocuted" in the title (electrocute = Injure or kill someone by electric shock). I just got shocked, not injured or killed :)

Apparently you are best to go and have an ECG done soon after a decent shock to check all is well with your heart, something I was not aware of.

Anyway, Electrician came today, summary is that there was a short in the wire between my stairwell light and it's switch that was livening the entire roof when that light was switched on. The roof has been bonded to earth, to avoid risk of further shocks (meaning the breaker blows when that light is switched on) and the electrician will come back after the lockdown with a team of two, to try and swap out the wire (no accessible roof space, so not easy).

Long story:

I switched on everything I could think may have been on when I was shocked, before the sparky arrived, checked the roof, and 236v was back again. Great news obviously much easier to trace an fault that is active at the time.
Sparky worked out which circuit was affected by switching breakers, affected breaker had multiple circuits fed from it, so sparky checked wired checked each individually.
Sparky checked various light fixtures & found a loose junction box above bathroom downlight, Thought it may have came into contact with the metallic air extraction ducting. He mad it safe, and checked the roof again and the voltage was gone.
I wasn't super confident that this was the issue, so asked about having the roof earthed. It was easy to do, so the sparky agreed. Made me feel safer.
Sparky packed up and did a last walk, and flicked a few switches on the affected circuit, one of which tripped the breaker
Removed the light fitting, and diagnosed a short to earth from one of the wires leading to the stairwell light.
Decided to fix the issue with two electricians after the lock-down, due to challenging access to affected wire.

Turns out the stuff with wetness, was a red hearing, and the fault occurring came down to if the affected light circuit was on or not. I was a bit surprised that the house was is electrically insulating enough not to trip a 10A breaker when the entire (I assume) roof was live, in the rain...