Reused shower cable (for heaters)

[kingeri]

I was called out yesterday to a house to have a look at a wall mounted heater in a bedroom that had stopped working. Had a quick look, and noticed that the heater was controlled by a 20A DP switch. No FCU. In the CU, it was on a 32A MCB. Upon further investigation, I found that there were two 3kw heaters on this circuit. Basically, the 10mm^2 shower circuit had been repurposed to supply these heaters. Nothing unusual about that but the way it was done was a bit rough (in my view). The 10mm^2 cable was terminated into a cooker outlet plate, then 2 x 2.5mm^2 cables came out of this plate, immediately into 2 x unswitched FCUs, then onto the heaters which had local 20A DP switches. I fixed her problem by simply replacing a fuse. But it got me thinking how I would have done this job and if the current situation is acceptable. The connections in the cooker outlet were sound, no cable can be overloaded, so at the time I couldn't immediately fault it. I suppose the cooker outlet wasn't designed for the purpose it is being used for. If I were doing this I would probably just stick a small 2 way CU with 2x 16A MCBs in it on the end of the 10mm^2, or find a more suitable way of joining the cables.
Any thoughts?

 

[Wilko]

The 2 x 16A MCBs would cover it. But I guess the question is - is it necessary? The 2.5 should be able to meet fault disconnection for 32A MCB ok (?) so it's overload current that remains. This was covered by the 13A FCUs used, but from immersions I've found many of these don't like 3kW loads. Does reg 433.3.1 (ii) help us? The heater draws 12.5A and it's hard to see (to me anyway ) how one could draw a current that would overload the 2.5 ?

 

[telectrix]

they are fixed loads, so over current protection is not required. only short circuit protection is needed.

 

[kingeri]

I suppose the local DP switches could have been switched FCUs instead (manufacturers instructions calling for local fuse)??

 

[Wilko]

... manufacturers instructions calling for local fuse ??

I have seen this with UFH and it cooked the FCU

 

[Octopus]

If the OP had fitted a small CU, where would it be located?

 

[Andy78]

I suppose the local DP switches could have been switched FCUs instead (manufacturers instructions calling for local fuse)??

Thought they were already fused down at the point where they split ?

 

[kingeri]

Thought they were already fused down at the point where they split ?

They are. But just thinking how this job could have been done differently (better).

 

[kingeri]

If the OP had fitted a small CU, where would it be located?

I am not fitting anything, just thinking about how the job was done. It could go where the 2 x FCUs are now, in a cupboard off the landing. Obviously the CU idea is totally unnecessary anyway!