overheating

[tflda29]

Hello,

Wondering if anyone can help with the following:-

Switch for electric shower has recently become extremely hot when in use with a smell of burning. The plastic cover has cracked with the heat. I removed the cover to look for a loose wire and found that about 3" of the grey cable cover is very burned, black and blistering.

The house is only 1 1/2 years old and so we are looking for Wimpey ti fix this, but wy question is, should the MCB not have tripped due to the high heat?

thanks
Trevor

 

[runci21]

sounds like you have a loose connection, the cable between shower and pull switch will need replacing and proberly a new shower unit.

 

[RobFurn]

It would be interesting to know what size MCB you have and what size cabe in mm sq is feeding the shower and what rating your shower is. Can you supply that information please

 

[runci21]

ive just read your post again was it the pull cord box or shower that was getting hot ???

 

[bernardgreen]

but wy question is, should the MCB not have tripped due to the high heat?

DO NOT USE THE SHOWER UNTIL THE SWITCH AND CABLE HAVE BEEN REPLACED REPAIRED Turn OFF the MCB for the shower as well.

The heating in the switch is due to a loose connection or damaged contact in the switch. Most likely is POOR INSTALLATION in that the terminals were not checkd for tightness.

No.... The MCB will not trip as the CURRENT flowing is still the same as it would be if the switch was in perfect order. ( slightly less in fact ) It would trip once the cable had melted enough to cause a short circuit with possible fire as several kilowatts of heat would be concentrated in that small area until the MCB tripped.

All that has happened is the poor contact in the switch has become resisitive to current and thus acted like a heating element.

 

[davy_owen_88]

An MCB will not trip due to heat build up caused by high resistance terminations. The only time they will is when the high temperature causes a short in the cable.

EDIT: Too slow again.

 

[tflda29]

thanks for all your quick replies.

There is no pull cord in the bathroom itself, just a switch outside the bathroom (one like a cooker switch to cut both neutral and live i think!!!!?)and it was this that is getting hot.

thanks again

Trevor