Shower Not Functioning - Apparent Voltage Drop...

[devans]

Hi everyone

Was wondering if anyone may be able to shed some light on a problem a friend is having with their shower. Before I start, I am a building surveyor, so I am well aware of the Building Regs and Part P - my friend and I don't plan on doing any work, but I said I would mention on here and was hoping for a bit more background information if possible.

Basically, a 9kW shower is not working - the 50A pull switch appears to be ok - when the cord is pulled, the neon light glows, however, when the shower 'on' switch is pressed (or a multimeter placed on the load terminals to check voltage), the neon light dims significantly and the shower doesn't turn on.

Using a basic multimeter, we have tested the supply to the switch which seems fine. However, on the load supply of the switch and at the shower choc block there is a large drop in power (power here seems to be around 25V) - why would this be? At first I thought it could just be the switch but why would there be such a large drop in power? Could it be a faulty cable between the switch and the shower? Also, apparently the switch has been replaced several times before (surely they don't fail that often), but I am concerned something more sinister is happening! Another point to mention, the DB was replaced - the shower is on a 32A breaker which I believe is significantly bellow what it should be (9kW @ 240v = 37.5A?), however, it has not been tripping the MCB. To be honest, I am concerned with the whole state of the installation... the DB was replaced by a local electrician (DB only, not wiring which is approx. 25 years old and overdue a serious check / renewal anyway ), surprise surprise no certs...

Anyway if anyone has any suggestions (other than getting the whole installation checked by a qualified electrician which I am going to say tomorrow) then I'd be interested to hear.


Thanks

 

[ricicle]

A difference in voltage across the switch would suggest that it is that at fault with a high resistance connection/contact. The VD would not manifest itself on the load terminals of the switch if it were the cable between that and the shower at fault.

 

[devans]

Ok thanks for the info. Any reason why so many switches should fail (I believe this is about the 3rd switch in a few years now).

 

[1john]

Switch failures normally result in people using the switch when it is not required. It is there for isolation for maintainance and servicing purposes. Also cheap switches dont last as well. As you know, a periodic inspection report is well due, check some main things are in place yourself like main equipotential bonding and that lighting circuits carry a CPC.

 

[skenk]

A cheap 50A pull switch will often break if used a lot. Also a loose connection can cause it to burn out. You should check the copper in the terminals at the switch is not damaged/discoloured

Also, if you are competent, check the connections in the CU, you could well have a loose connection on the neutral (or line).

If you do decide to open the CU then be safe. Even with the main switch off the incoming terminals are still live.