Shower trips RCD...

[gowerjack]

Old Triton shower tripped RCD so I replaced today with new Triton shower.

Still trips RCD ( maybe old one wasnt faulty?)

8.5KW on Wylex B40 mcb, 6mm 6242yh ( but only approx 5mtr run ).

RCD & MCB hold untill I switch on at ceiling switch,then trips RCD but not MCB ( so earth fault not overcurrent).

Linked out switch same result,changed switch same result.

Cable is surface & shows no sign of damage.

Am not prof sparkie so no test equipment.

Do I need to replace the cable from the switch to the shower?

Can anyone advise?

Thanks in advance

Steve

 

[nickblake]

Firstly one of the problems with showers is the pull switch so many cheap ones about and one of the biggest problems ive found is the termials burning out so id check there first , disconnect the shower circuit from the board and carry out all the tests as usual ,continuity the the IR right down to the shower and see if there are any faults ,one thing i would do if the cable is 6mm reduce the size of the mcb to 32 amp if the cable runs through the loft and covered in less that 100mm of insulation then the cable is only rated at 34 amps
sorry just red your post proprly have you got the L and n the wrong way round

also sorry to point out if you repace any cables it falls under Part P and the work is notifiable

 

[davelerave]

you need to IR the cables

should be simple fault

 

[ezzzekiel]

Am not prof sparkie so no test equipment.

may prove a little difficult to test then

any signs of water dripping?

 

[gowerjack]

Swith is Ok replaced with brand new MEM product.

L & N are correct !

I am competent enough to replace a cable so will "draw a veil" over the part P !

Thank you all for the replies

 

[kung]

As said needs testing ! you can do continuity test from discon shower circuit test cpc-l with multimeter then discon switch and do same ! then same with n-e etc that should tell you what leg is at fault if not ir test needs doing.

 

[calv68]

i would check if its 8.5 kw at 230v or 240v sounds like your on the limit with 6mm cable i allways run a 10mm cable if the shower is above 7.8kw better safe than sorry mate ive seen loads catch fire

 

[kung]

i would check if its 8.5 kw at 230v or 240v sounds like your on the limit with 6mm cable i allways run a 10mm cable if the shower is above 7.8kw better safe than sorry mate ive seen loads catch fire

Yer i have an 8.5 and at home and always install a 10 as gives me the option of uprating if i want without pulling tiles off ect to get to cable for rewire.

 

[SirKit Breaker]

Swith is Ok replaced with brand new MEM product.

L & N are correct !

I am competent enough to replace a cable so will "draw a veil" over the part P !

Thank you all for the replies

Get a new piece of cable and lash it in temporary to see if it gets rid of fault.

Cheers.............Howard

 

[GrannySmiff]

If its not cable then maybe RCD is faulty?? when you do the RCD test the first test you do is the nuisance tripping test so could it be this maybe.

How often does this occur I.E. a working RCD starts to fail mechanically?.

 

[gowerjack]

All sorted

Replaced cable from switch to shower,now all ok and I`m clean....

Thanks to all for the help!

If you are ever in Neweys Swansea I`ll get you a coffee!