Electric Shower Cabling

[monstamash]

Hi All

Looking for some advise from an expert as I have had 2 electricians out with two very different views.

I have an 8.5 Kw electric shower, with 6mm cabling. The light on the wall switch started flickering, and eventually went out. Turned out the wires at the switch had started melting.

One electrician has advised me that the whole thing needs rewiring with 10mm cable from the main box to the switch and then to the shower (and I think he said a new RC switch too?).

The other said as it was likely a faulty connection on the wall switch. Just needs a new wall switch and repair the melted part of the cable. He also said that as it is only a few meters from main box to switch and another couple meters to shower 6mm cable is fine.

Can anyone form an opinion without seeing it?

I dont mind paying to get the job done properly, but at the same time dont want to destroy and re-plaster walls unnecessarily.

Thanks in advance!

Andy

 

[EFLImpudence]

The other said as it was likely a faulty connection on the wall switch. Just needs a new wall switch and repair the melted part of the cable. He also said that as it is only a few meters from main box to switch and another couple meters to shower 6mm cable is fine.

That is correct.


RC ? Likely RCD - a safety device which would be beneficial.

 

[monstamash]

Thanks for your advise EFLImpudence. Appreciated

 

[flyingsparks]

Is the cable covered in insulation at any point along its length?
What size mcb or fuse is protecting the cable?

 

[ban-all-sheds]

One electrician has advised me that the whole thing needs rewiring with 10mm cable from the main box to the switch and then to the shower

Either:

1) He was not an electrician

or

2) He was one of the lying, cheating, thieving, rogue trader variety.

Either way, have nothing to do with him, and if he is registered with NICEIC or NAPIT etc, please report him to them.

 

[PrenticeBoyofDerry]

One electrician has advised me that the whole thing needs rewiring with 10mm cable from the main box to the switch and then to the shower (and I think he said a new RC switch too?).

Mostly untrue. But it would be good advise to have RCD protection on electrical equipment in bath/shower rooms. But depending when the installation was installed, would depend on whether this be a requirement/regulation at that time.

The other said as it was likely a faulty connection on the wall switch. Just needs a new wall switch and repair the melted part of the cable. He also said that as it is only a few meters from main box to switch and another couple meters to shower 6mm cable is fine.

This is the type of diagnosis you should be expecting, the issue is highly likely to be a bad contact at the switch terminals, that has led to overheating. So remedial work to the damaged cable, if enough slack on this cable, this can be stripped back and cleaned up and re-terminated to a new isolation switch.
If cable cannot be repaired in this way it may require a new length of cable or a remedial joint making (the joint would need to be either accessible or a maintenance free method used).

If the cable does need replacing throughout? Then it would be a logical consideration to at that time increase cable CSA to 10mm2, this would allow for a higher rated shower to be fitted at a later date, if desired.

Can anyone form an opinion without seeing it?

By the evidence you have given, the replies offered so far on this site and the second electrician is the advice you should act on.

I dont mind paying to get the job done properly, but at the same time dont want to destroy and re-plaster walls unnecessarily.

The second electrician is the one I would be employing, based on your evidence.

 

[Cabbyfan]

Cable size depends on additional factors not just the Kw rating of the shower. If the cable run is long or if it runs through a loft space with lots of insulation etc, this needs taking into consideration.

Any electrician should point this out and do a cable size calculation accordingly.

As for your melting issue, yes most likely local heat buildup due to poor switch quality or loose bad connection.