Cables burnt behind fused spur supplying immersion heater

[galaxy_electric]

I went to a house last week where the live cable on the supply side of a spur (old colours, red) was coloured black as it had been burnt by what looked to be arcing due to loose connection. So i changed the old spur for a new one, as the old spur was all burnt and discoloured. Now the customer has called me up and saying the new one has started to burn as well.

Has anyone got any suggestions on what could be causing this problem?

 

[Spa Key]

I went to a house last week where the live cable on the supply side of a spur (old colours, red) was coloured black as it had been burnt by what looked to be arcing due to loose connection. So i changed the old spur for a new one, as the old spur was all burnt and discoloured. Now the customer has called me up and saying the new one has started to burn as well.

Has anyone got any suggestions on what could be causing this problem?

Immersion heaters are usually 16A, and so have their own radial. Why is it spurred, and from what?

Also, how is it spurred? JB, FCU, etc?

 

[cegsdj]

does the thermostat on the tank work ?and are all the connections secure tank spur etc ?

 

[Andyfm]

Poor quality spurs? - Its not feeding a timer switch for two elements is it ?-
Standard elements done not draw more than 13 amps so it should work with no problems

 

[galaxy_electric]

Immersion has not been spured off a circuit. The fuse spur is just for isolation purposes

 

[Hawk81]

i would fit a 20amp double pole water heater switch. I have never had a problem with them. Have you clamped the immersion heater?

 

[galaxy_electric]

Clamp the immersion heater? what do you mean? earth clamp?

 

[Hawk81]

Clamp the immersion heater? what do you mean? earth clamp?

i mean use a clamp meter to see how many amps the immersion heater is drawing when switched on.

 

[chris gray]

id bin the fcu and fit a 20A DP isolator personally, so long as it is on a lower rated circuit at the board.
the amp clamp is good advice though.
the discolouration will be down to bad connection or overload.

 

[topquark]

does the thermostat on the tank work ?and are all the connections secure tank spur etc ?

I'd suspect the same, the thermo is very often on the heating element these days and are known to be a source of problems (don't cut out so continue drawing max current).

 

[GStueyXR]

Cant believe you never tested the circuit to prove that burning was purely from loose connection.

Then you ask for advice without giving details of CSA of cable, power rating of immersion heater, means of OC protection, means of additional protection etc....