Shower Issue

[Englishman]

Went to a job today as a follow on from another sparks on our firm. Was a "fishy smell" reported, and was advised that the cable was undersized.

Get there today and find a 6mm cable, 40a MCB and 9.5kw shower; and this in the isolater...

Now, the supply voltage is 242, the cable run goes from the board, up to the first floor in a piece of conduit in the wall (reference method A) which rates at 34a, and then up a void behind the shower, clipped direct (reference method which rates the cable at 47a.

Obviously the cable at the lowest part (bit going through conduit) is carrying 39.25a; which is greater than 34a, and they're sending me back to put a 10mm supply in tomorrow. My argument is that the damage to the cable has been caused by a loose neutral at the isolater and that although the cable is undersized, it's not massively bad and probably wouldn't cause a huge amount of issues if the shower was run normally.

Opinions please boys....

 

[topquark]

Burning is only on the neutral term, so defo down to a poor neutral termination. You've been told to replace, so you should. However, I doubt it draws its rated max load in use!

 

[Meggerman]

Burning is only on the neutral term, so defo down to a poor neutral termination. You've been told to replace, so you should. However, I doubt it draws its rated max load in use!

I'd just replace switch if it were me, the damage was caused by loose termination. They run for such a short time, in reality 6mm will never be a problem. There are plenty of 9.5kw showers on 32A MCB's.

 

[topquark]

Borderline, depending on applied derating, 6mm is good to 40A CCC before derating...depends how where it's run....putty they don't do 35A breakers ... bet it would hold!

 

[topquark]

I've clamped a few when running ... pull a little more than 32A on start up (but not much).

 

[Pete999]

Loose Neutral by the looks of it

 

[7029 dave]

I go with that Pete.

 

[robd]

Personally always advise customers to leave switch in the on position on the isolator which stops the wear and tear...whether or not they listen to me is another thing

 

[GMES]

I go with that Dave

 

[Englishman]

I know it's the loose neutral which has caused the issue that I responded to.

What I'm referring to the forum is how much it actually needs to be changed. And how much of an issue would be caused by leaving it.

 

[SirKit Breaker]

Loose Neutral by the looks of it

Definitely, i have done loads of these. just hope that whoever installed it, left plenty of cable so you can pull it well clear of the ceiling to re terminate it a bit easier!

Cheers..............Howard

 

[Hawk81]

I would say it might not be a loose neutral connection. The other possibility is the pull cord itself is at fault. I have replaced 4 GET 45amp pullcords in this last week. All looked identical to that in the picture. I do a lot of maintenance for an estate agent and the most of the calls I get are showers and 9/10 its the pullcord. Try a different make as well as insuring all terminations are tight.

 

[Englishman]

As I wrote in the first post, I know that the problem is at the isolator.

What I want discussed is the cable suitability. The only part where it doesn't comply is the metre drop down to the CU. Would you leave the cable and mcb, downrare the mcb or just rewire.

Highly likely I'll have to rewire tomorrow but I just think it's unnecessary.

 

[topquark]

I would replace it. That's what you were asked to do. Maybe there's a pending upgrade in plan to 12KW in the near future.

 

[Lagentium]

Will a 10mm twin fit up the conduit? They are quite large by twin and earth standards. I've changed them too in the past, I think it doesn't help that they get twisted all over the show to get them to fit back if someone has fitted a box that's too shallow and it loosens the connections slightly