new shower tripping

[xAlex]

Hi all,

I helped a friend install a new shower. 7.8-8.5kW. 6mm cable (already there), new 40A MCB + 30ma RCD pod (effectively an RCBO). Just got a text to say it's tripping. It trips after being on for a few minutes.
In theory, the cable should be good for 46A. He said it did not run through thermal insulation, but i did not check this.
Question is: what's the most likely cause? If it does run through thermal insulation - reducing the current-carrying capacity, would this trip an RCBO? I guess the other problem could be that the insulation resistance is low but this may not have shown up on the old shower which was only protected by a 32A MCB. Any advice appreciated.

I don't have a tester and would like to get the thing working before the test are carried out.

Thanks so.

 

[oharaf]

Have you tried powering up without the POD in place just using the MCB?

If it does not trip here it is fairly safe to say your have an earth fault, or a faulty pod (don't like them myself).

I personally would have replaced that cable with 10mm, it is just the way i am.

You really need to test the cable anyway, you should not energise a circuit prior to testing.

Who is going to test it anyway?

 

[PrenticeBoyofDerry]

I'd have thought the wisest thing to do was to get an electrician in to test prior to powering up the circuit.

 

[oharaf]

True Prentice but sometimes you get the feeling that people don't want to and the 'Tester' coming is totally fictitious!!!

 

[xAlex]

Derisory comments after only 3 posts. Is that a record?

 

[PrenticeBoyofDerry]

True Prentice but sometimes you get the feeling that people don't want to and the 'Tester' coming is totally fictitious!!!

Yeh, you'd also think that considering the location and the possible dangers, that would be the first thing on the agenda. Not lets get it going then test it

 

[PrenticeBoyofDerry]

Derisory comments after only 3 posts. Is that a record?

Is it

 

[xAlex]

...so what happens when the Council come in to test and it's not working? Anyway, can you two get a room. You're not helping.

 

[PrenticeBoyofDerry]

Thinking about your safety mate, I don't know if your pal was an electrician or if you are what?
was it notifiable work?
who's signed it off?

 

[xAlex]

...surely you should know if fitting a new shower is notifiable.

 

[PrenticeBoyofDerry]

If it's like for like chances are you get away with it, but seeing you've installed new MCB. Yeh it's notifiable

 

[xAlex]

OK, thanks Guys.

 

[PrenticeBoyofDerry]

Sounds like council man had a look at it then, did they do the testing?

 

[PrenticeBoyofDerry]

Chances are earth leakage, could be in cable if IR not up to stratch or moisture ingress or fault on shower

 

[xAlex]

...cheers, i'll get a man with a meter.