Electrics RCD Question

[SinsSinatti]

Hi,

I hope this question is ok.

About 6 weeks ago my cooker tripped the RCD. When the electrician came, the plug socket was partially melted, he changed that, still unconvinced it wasn't a cooker problem. Cooker started working fine again.

Today, my tumble dryer tripped the RCD. Whilst the cooker was 6 year old (but not often used), the tumble dryer is less than 1 year old. It was plugged into a socket I had an issue with several years ago. The socket stopped working at that time & started to smell of singeing. I had the socket replaced & mentioned the smell but told just the socket.

Today I changed the fuse on the tumble dryer plug to be on the safe side & tried to turn it on again. Half the double socket is now not working, where it had been originally plugged in. Tumble dryer working fine in another socket.

I don't use extension leads or double adaptors in the kitchen. At the time it fused, only the washing machine, tumble dryer & electric heating controls were in use.


Anyone know what the liklihood is that this is an internal wiring issue?

Thanks

 

[AndyPRK]

A picture of what tripped would be helpful.
And point out the circuit breaker for the tumble drier and washing machine

Maybe a new plug and socket for the tumble drier would be a good move. Is it out of warranty?

 

[Murdochcat]

Sockets used with tumble dryers are prone to failure.

 

[SinsSinatti]

A picture of what tripped would be helpful.
And point out the circuit breaker for the tumble drier and washing machine

Maybe a new plug and socket for the tumble drier would be a good move. Is it out of warranty?

Thanks for the reply. I've encircled the switch that tripped. Same last time too. The tumble dryer would fall under kitchen sockets #2 although that switch didn't trip.

 

[AndyPRK]

Probably need to get an electrical to check for leakage across the circuits if it happens again or reliably.

Either clean the dryers brass plug pins so nice a shiny. (Use Scourer or timescale remover) or replace the plug.

 

[SinsSinatti]

Probably need to get an electrical to check for leakage across the circuits if it happens again or reliably.

Either clean the dryers brass plug pins so nice a shiny. (Use Scourer or timescale remover) or replace the plug.

Andy, thank you for that, very helpful. Appreciate it!

 

[opps]

I am not an electrician...

The OP's RCD is rated at 80A, it is significantly lower than the max of the MCBs (114A).

The left hand side is rated at 63A and the MCB max load is 116A.

Is that common?

Edit--- my lay understanding of the following says that they shouldn't be overloaded, but perhaps I have read page 9 incorrectly

https://assets.sc.hager.com/uk/-/media/project/hagerdeep/united-kingdom/hager/b2b/products/catalogues-and-brochures/pdf_brochures-and-docs/product-catalogues/2022/updated-residential-catalogue.pdf?la=en-gb

 

[AndyPRK]

Not uncommon.

It’s something ppl started to get excited about a few years ago.

In reality the whole house will either be on a 60 or 80 amp supply so not an issue.

They are trying to phase out 100A supply’s in the modern EV world

 

[opps]

Not uncommon.

It’s something ppl started to get excited about a few years ago.

In reality the whole house will either be on a 60 or 80 amp supply so not an issue.

They are trying to phase out 100A supply’s in the modern EV world

Thanks for the reply. So why does the OP have two different ratings for their RCDs?

 

[AndyPRK]

They don’t trip at that current.

The wires inside are just thick enough to carry that current.
More current, more copper, more money.

So cheaper manufactures supply a mix to cut costs. And hope the electrican notices

 

[flameport]

Solar on a shared RCD. Good luck with that.

 

[opps]

They don’t trip at that current.

The wires inside are just thick enough to carry that current.
More current, more copper, more money.

So cheaper manufactures supply a mix to cut costs. And hope the electrican notices

Thanks, I did work on the assumption that they didn't trip on current, but didn't understand why they had individual ratings.

 

[Murdochcat]

Solar on a shared RCD. Good luck with that.

An extremely common mistake sadly.

The big book still isn’t clear on the matter yet EVs must have a dedicated RCD - go figure

 

[Murdochcat]

Thanks for the reply. So why does the OP have two different ratings for their RCDs?

Most CU’s used to be sold like that

 

[ericmark]

Each item can leak a little bit,

my meter here is showing total of 8 mA, in theroy allowed 9 mA in normal use, but the RCD will likely trip at around 27 mA so in real terms a leakage of 18 mA would be enough to trip a single RCD, not 30 mA so we use RCBO's so every circuit has its own RCD, this is far less likely to trip.

Basic thing is if done on the cheap, then more likely to trip. And unless you have a meter like mine, you are simply crossing ones finger and hope it will be OK.

I had a think about it when I came to change the CU in this house, and decided one freezer full of food lost, was more money down the drain than the extra needed for all RCBO CU.

But I have lived in a caravan with one RCD for all, and had no problems, so some times we can get away with just 2 RCD's well in your case with solar likely need at least 3. A type A RCD is only good for 6 mA DC there should not be any DC, but as long as the circuits don't share the RCD the risk is low, so with what we know today, we should not be sharing a RCD with solar or EV charge points.

At the time of fitting CU with just 2 RCD's we did not understand the dangers of RCD's freezing due to DC.