shower switch

[paddy1]

We recently fitted a new bathroom and installed a new electric shower along with a new 45Amp double pole pullcord switch.
Note: there was an existing 30Amp fuse running from the consumer unit with 6mm cable to the old shower unit and also 6mm cable running from the old shower to the old shower switch.

After using the shower for a while there was a very strong Fish smell when the shower was being used. Being aware of electrics I knew that it was something burning somewhere and immediately turned off the shower and removed the switch to check the wiring.
There was burn marks at the neutral terminal from the shower cable.

I noted that the Live and netral from the shower were connected to the Neutral and Live on the Load terminal of the switch which was incorrect.

Does it matter weather the load cable from the consumer unit is connected to the load terminals of the swich?
Would this have been the cause of the problem or is it just that the wire was not secured in the terminal correctly.

Thanks.

 

[Panjandrum]

Shower = load. Apart from possible confusion to others, the fact that L and N are reversed should not be a big deal. Your scorch marks are most likely to be poor connection or dying switch.

 

[delmel]

I would agree and hazzard a poor connection loose terminal.

 

[Screwi]

Its quite possible if your shower is a high power i.e. 10.5 or 11.5kw then you are overloading the 6mm cable and the fuse/breaker in the cu.

If your shower is a high power one you need 10mm cable and a bigger breaker/fuse, if the shower is one of those 11.8kw triton things then even the DP switch is too small for a load of that size.

What is the kw rating of the shower????

 

[Steve]

Hi people, thought i'd tell my story here!

Last year the pull cord shower switch in our bathroom snapped and the switch unit itself was hidden in the ceiling void above a false ceiling. Down came the false ceiling, and i opened up the switch. What I saw alarmed me somewhat. The live feed to the switch was black and badly corroded, and the insulation had melted right off it. the backbox had to be snapped off the ceiling, it had melted to the artex. The rest of the wires were fine, but the black switch back had cracked with the heat. I was surprised the 30A MCB had never tripped, and that the 9.5KW shower actually worked fine with this arrangement!

Any suggestions what caused this? A loose connection is a possibility, but no smell was ever detected, it had been there untouched a good 6-7 years. The original circuit was in 6mm T+E. Anyway, a decision was made to replace this with 10mm from 40A MCB, through conduit on surface of bathroom tiles, through new switch on false ceiling, to a new 10.5kw shower, since the old one was making weird noises!. A lot of work for a broken bit of string!

 

[plugwash]

loose connections are the normal cause of this kind of damage

they have a much higher resistance than good connections which means a lot of heat is generated that doesn't really have anywhere to go

as for a 32A breaker remember breakers will stand 1.5 times overload for quite some time before tripping and showers are not normally run for extended periods.