Shower is tripping the mcb

[Monkeh]

Looks like an empty plastic box to me.

 

[flameport]

That previous item IS just an empty box.

Something like this:
http://www.screwfix.com/prods/36269/
would most likely be suitable.

 

[RADabz]

Isn't my empty box just an empty box with a 45a mcb in it ??

That one looks just like a switch to me ?

 

[RADabz]

and isn't this just newer stuff different box ??

http://www.screwfix.com/prods/36269/?source=aw&cm_mmc=AffiliateWindow-_-DeepLink-_-Na-_-Na

I mean I'm not going to use the 65a bit am i ?

The 45a bit just says mcb, which is what i have already???

 

[LoveRocket]

You get an empty box, fit it with a 40amp Double Pole RCBO.

An RCBO combines the overcurrent protection of an MCB, and the residual current protection of an RCCB.

 

[RADabz]

hmm,

small victory, the new bit arrived and the shower run for 15mins without tripping but the mcb did get warm, is this normal ??

I think not and I'm suspecting maybe a loose connection somewhere ?

 

[ban-all-sheds]

small victory,

No, just a temporary delay of the inevitable.

the new bit arrived and the shower run for 15mins without tripping but the mcb did get warm, is this normal ??

No.

I think not and I'm suspecting maybe a loose connection somewhere ?

45A and 10mm² should be fine for a 10+kW shower, so neither should get hot if properly installed.

Loose connections can cause overheating

Replacing the MCB may resolve the problem, however it is likely that the contacts where the MCB plugs into the board have been overheated and damaged, or perhaps the wires connected to the board are loose/damaged.

The real solution is to replace the shower fusebox completely.

Definitely have that old fusebox for the shower replaced.

It has no RCD, is probably damaged internally from the overheating.

 

[RADabz]

I'm going to get a friend who's a sparky to have a look behind the box as I think there must be a loose connection behind it as everything else seems ok.

 

[securespark]

How can there be a loose connection behind it if you've just changed it for a new one?

 

[Monkeh]

How can there be a loose connection behind it if you've just changed it for a new one?

Plug-in breaker?

 

[securespark]

OK fair enough. I thought the OP had followed advice & fitted a DP unit.

There may be loose connections on the pins to the plug-in MCB, or loose conns in the CU.

 

[RADabz]

Hi all,

I doesn't actually appear to be heating up, I think it must have just been the heat of my hand checking it every minute or so.

Looks like it's fine now although I have noticed that it's 6mm cable coming into the bottom of the box with the breaker in it, although 6mm should be fine for 8.5Kw.

Once I get back from Honeymoon I think I will fit an RCBO (or get a spark to do it), question though can I get a separate unit or does the RCBO need to be fitted to my existing fusebox ?. There is a circuit for the shed which to be honest I don't use just now so I could loose that.

Cheers,

 

[ban-all-sheds]

Looks like it's fine now although I have noticed that it's 6mm cable coming into the bottom of the box with the breaker in it, although 6mm should be fine for 8.5Kw.

But what matters is is it fine to be protected by just the service fuse?

//www.diynot.com/wiki/electrics:mcbtocable

And the answer is probably not.

Once I get back from Honeymoon I think I will fit an RCBO (or get a spark to do it), question though can I get a separate unit or does the RCBO need to be fitted to my existing fusebox ?. There is a circuit for the shed which to be honest I don't use just now so I could loose that.

1) Don't know about the MK ones, but in the Siemens range that those were based on the RCBOs are 2 or 2.5 modules wide. I expect the MK badged ones are just that - badged, so an RCBO wouldn't fit.

2) You don't need one anyway, because the CU has got an RCD.

 

[RADabz]

It's not even covered by the service fuse.

If I switch off the main fuse the shower still gets power, I have to switch off the box with the MCB in it to kill power to the shower.

So in short the shower is wired in before any of the fuses.

I don't know why it is and I'm not happy about it at all.

I think I might get the whole lot rewired once I get back from honeymoon, but it's just too much to get sorted 4 days before I get married...

There are photo's of it further back this thread.

 

[ban-all-sheds]

It's not even covered by the service fuse.

Yes it is. The service fuse is the one on your incoming supply, before the meter.

If I switch off the main fuse the shower still gets power,

You can't switch off the service fuse. What do you mean by "main fuse"?

I have to switch off the box with the MCB in it to kill power to the shower.

That would mean that the shower fuse enclosure was supplied from the output terminals of the RCD.

switching the main off button on the main fuse box does not switch off the shower power.

That contradicts what you just said, and would mean that the that the shower fuse enclosure was supplied from the input terminals of the RCD.

So in short the shower is wired in before any of the fuses.

It's after the service fuse, but that's not adequate.

I don't know why it is

It was installed by an idiot.

You should start to wonder what else that idiot might have done.

and I'm not happy about it at all.

Nor should you be.

I think I might get the whole lot rewired once I get back from honeymoon, but it's just too much to get sorted 4 days before I get married...

Don't put it off too long.