Shower Pullcord

[Sparky Stu]

I am an adult trainee and i am trying to understand a problem that i must have with my shower pullcord isolater in my bathroom. Recently it has burnt out and was wondering what has caused this, as i have replaced this isolator a few times over the years.

The neutral cable on the load side is the cable that has always burnt out. The cable is 10mm and the length of run cannot be that great as c/u is located in the kitchen directly under my bathroom. The shower is 8.5kw on a 40A 60898 MCB.

Each time i have replaced this pullcord i have stripped the cable back to where the cable is in good condition. Just looking for some possible answers as cable is now beginning to get a bit on the short side from all the previous stripping back. Cheers Stu

 

[Mark.W]

It sounds like the neutral is loose!

It could be that the 10mm cable is a bit too big for the terminals and not in properly. The design current is only 37a therefore you can get away with 6mm cable!

Also what is the rating of the switch?

Mark

 

[bugsy]

Loose connection , use a good quailty 45a pull switch

 

[gpz900jim]

as above, buy an mk one or similar, cheaper ones are likely to burn out, especially if kids use the shower as they are in there ages. tighten those screws up real tight

 

[malcolmsanford]

Also make sure you use the units, power on/off switch to actually turn the shower off. Quite often people just use the pull cord to turn the shower off and therfore your switching under load, which will reduce the life of perhaps cheaper switches.

 

[sjm]

I only fit the 50amp Crabtree ceiling pull switch now as the old 45amp square ones are difficult to wire and prone to suffer from loose connections and burning out. The Crabtree is well designed and easy to wire with 10mm cable, also when you remove the cover the neon is removed as well. IMHO a very well thought out piece of kit and well worth checking out.

 

[alanl]

It is most likely to be a poor connection at the screw-in terminal on the switch. I've seen this lots of times in all sorts of fittings.

Make sure the screw is really tight, the inside of the terminal is clean, and the wire is also clean. Check the other screws as well.
Alan.

 

[Sparky Stu]

Thanks for all your replys, normally i make sure that the terminals are tight. Just had a thought that if the cable was stripped so that the amount of cable showing to be terminated was too long could this pertrude from the other end of the terminal and cause arking therefore resulting in the switch burning out?

 

[GT1]

Pretty much always going to be poor connections that cause burning at cable terminations. As others have said it could also be poor quality switch gear.

 

[Engineer54]

Crabtree 50A pull switch each and every time!!! As your wiring slack is almost gone now, buy the best and reject the rest, next time it's a rewire job!! lol!!!

 

[mechelec]

When terminating stranded cable over 6mm i tighten the terminal, wiggle the wire back and forward slightly and tighten again. This seems to settle the strands and the screw almost always goes another quarter turn. Never had wire overheat yet. ( i shoulnt have said that should i)

 

[Roger]

A friend on mine asked me to connect up a electric shower today 10.5kw and a 45 amp pull cord isolator located in zone 1 about 300mm from shower head.It was inside the shower screen side of the bath !!!
I said no and he got the hump because the client asked him to put it there and he does not have enough cable to relocate it.It also finished tiled but yet to be grouted.
She was not keen on having it outside the bathroom and she also did not want to have a extractor fan fitted because of the noise !
Wish I was never asked.
I said isolator should be 3 metres away or outside room.
Back tomorrow for a chat and a biscuit and probably leave him some 10 twin & earth.

 

[R1CH-G]

As most of the other guys have said - loose neutral. Recently had a similar incident on a main incomer chattering on the neutral - wasn't picked up on routine maintenance. Ended up costing a load of moolah!

 

[SimpleSimon]

A friend on mine asked me to connect up a electric shower today 10.5kw and a 45 amp pull cord isolator located in zone 1 about 300mm from shower head.It was inside the shower screen side of the bath !!!
I said no and he got the hump because the client asked him to put it there and he does not have enough cable to relocate it.It also finished tiled but yet to be grouted.
She was not keen on having it outside the bathroom and she also did not want to have a extractor fan fitted because of the noise !
Wish I was never asked.
I said isolator should be 3 metres away or outside room.
Back tomorrow for a chat and a biscuit and probably leave him some 10 twin & earth.

A pull cord isolator does not have to be 3m away. A DP switch does. A pull cord can be located 600mm away from the edge of shower basin. It can also be located in zone 1 if the switching mechanism on the ceiling is 2.25m from the basin floor.

 

[Roger]

Many thanks SimpleSimon.
Your spot on as per OSG but I am amazed that you could have a pull cord switch within zone 1 at all.I would never have it in my house with all that condensation in the shower,seems daft.
I must confess that all shower fitted I always locate a DP isolator outside,don't like pull switches seems old fashioned to me.
Thanks again.