Wall switches getting hot!


Postby dns » Thu Sep 10, 2009 12:59 pm

Thought I'd test my storage heaters last night as I've never used them before.

They worked nicely, but I was a little shocked to find that the wall switches for two of them were very hot to touch. I've checked and both are correctly rated. The cable in the walls is also of the correct rating.

Any ideas what could cause this?

The problem occurs with the 2 heaters in my living room, which both have a wall connection with a single switch and no fuse (looks like a single light switch, but with a flex entry point).

I don't have this problem with the heater in my hall, which has a very similar switch (only for some reason this one has a light!)
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Postby kbrownie » Thu Sep 10, 2009 6:13 pm

How do you know they are fused and wired correctly and the accessory is correctly rated?
What output are the heaters,
what size and type of cable is being used
what breaker size is protecting the circuit,
are they on the same circuit?
KB
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Postby chriscba » Thu Sep 10, 2009 9:53 pm

The switches should be a 20 amp double pole switch [switches live & neutral] The red light is just a neon light, if you have a 10 amp single pole light switch there, it will get hot, get it checked by a electrician.
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Postby bd3cc » Thu Sep 10, 2009 10:11 pm

Check the tightness of all terminal screws as a loose connection can produce heat.
Also the lounge heaters may be bigger, draw more current than the hall heater, and therefore the switches may be warmer.
I think the neon may be irrelevant, just a previous occupant wanting to know when that particular unit was on.
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Postby dns » Fri Sep 11, 2009 9:49 am

The switches are all rated to 20 amps. Each heater is on it's own circuit, protected by a 16 amp breaker. Cabling is the same 2.5mm2 twin and earth used for the sockets.

All the heaters are identical in appearance, unfortunatly I don't know the ratings.
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Postby kbrownie » Sat Sep 12, 2009 9:06 pm

2.5 twin and earth can carry up to 27Amps, but if the cable is grouped with other cables and run through thermal insulation this can more than half the current carrying capicity of the cable. So in an extreme case your cable may only be safely able to carry 13Amps. If this is true and you have 16Amp protecting the circuit that could be a cause for heat.
Doe the heaters also have a flex connection via the switches to the heater what is the CSA of them?
Also as previously mentioned tighten terminals up if loose this can also cause heating problems.
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