Maximum RCD size for a house

[bk81]

Hi Everyone,

I'm going to a house to check an rcd that keeps tripping, think it's an 80A 30mA. I'm thinking of upgrading the rcd as it is the main switch for the consumer unit.

Anyone know what I can use? Like time delay, up it to 100mA, not sure if they're not for domestic use?

Cheers all.

 

[Dazza2312]

Only been workin as an adult trainee for about 3 years but pretty sure it needs to be 30mA cause its for personal protection dont quote me and i'm sure someone will correct me if i'm wrong

 

[stitch]

There is surely a fault somewhere if the RCD is tripping all the time.

 

[telectrix]

by doing that, you would leave yourself wide open, as you would be making the installation less safe and not complying to regs. you must test the installation to find what is causing it to trip , ramp test the RCD and replace if necessary. but must replace with 30mA.

 

[bk81]

Cheers guys,

Trying to keep myself right, I'm taking a replacement with me just incase.

Someone else checked it last night, told them all the usual take everything off the circuit to see the problem. They insisted nothing was plugged in or switched and he rcd was still tripping.

Hopefully they've missed the one thing that's making it trip, and I'll be in and out!

 

[tvrelectrical]

Ramp test the RCD, circuit(s) disconnected. IR test the circuit(s) connected to the RCD. Must be 30mA RCD though if its installed for additional protection, don't just swap it out for 100mA! You've got to find the fault.

 

[Jurassic Sparks]

it could have an earth to neutral fault on the lighting circuit, sockets, or cooker
so even if you unplugged everything the fault is still in place
i would also carry out an insulation test between all poles, after isolating smoke detectors and any electronic equipment

 

[Amp David]

Start with a full RCD test and include a ramp test if your meter does it. If all checks out fine the i'd test each circuit being fed via that rcd

 

[Octopus]

Could there be ingress of water? has a rodent chewed a cable? Has somebody been putting up pictures and nailed a cable. Just because nothing is plugged in doesn't always mean the fault is with the RCD!

 

[bk81]

Found the problem, a kitchen fitter had taken out a socket, put the live and neutral in connector block and twisted the cpc's together which were touching the metal box of the cooker switch which had been moved up an inch. The cooker box was cutting into the load side neutral.

Only took an hour to find and sort it, not so bad for the mess that was made...kitchen fitters pretending to be sparks...

 

[bk81]

Murdoch, I was only taking an rcd as a precaution to save time having to find a wholesalers, obviously replacing the rcd in this case wouldn't have fixed the problem. It was more of a wondering of the maximum size for domestic premises as I've fitted a few higher than that in highways equipment.

As you can see above it was more of a one off story reason that was causing the tripping, thankfully found quite quickly.

I was merely giving advice over the phone to avoid having to travel an hour to see the house and could only assume on the information given, which, unsurprisingly wasn't very good.

 

[Geoffsd]

I hope house owner is sending kitchen company a nice big bill.

 

[Jurassic Sparks]

oh no kitchen fitters
seen it all before
the trouble is convincine the client how long it takes
you have to be thorough or you get called back
I always go through ti with a fine tooth comb as once you find one fault more will be waiting and its better to fix them once than to come back
its good experience though
I once had a house that kept tripping out, several sparkies had visited but done very little actual testing
I had a good wlak round first inside and out
noticed an outside light with the wire coming down the wall into the fitting
wipped it off, corroded solid full of water!!!
an hours work to cut back the cable, fit a joint box and run a new cable correctly fed and no more problems

 

[1shortcircuit]

So did this work by the kitchen fitter get notified?

From what you have described I'm thinking VERY unlikely

Nice find :thumbsup