Is it safe to swap tripping 32A MCB to 50A?

[CP76]

Hi, i would very much appreciate some advice regarding an increase to a 50A MCB and want to check before i switch them over.

I have a 10.5W triton shower which is cabled via a wall mounted (outside of bathroom) 45A isolation switch.

The cable runs under floor boards (no insulation) directly to a seperate wylex unit (cat no 104) under the stairs which has an on/off switch and a plug in 32A MCB. This unit is 30A rated and is wired to the mains board. Dont know what the tech name for this is think it's called a switchfuse!
The run is about 5 metres from the shower to the switchfuse.

The shower wiring is 6mm2 and has plastic capping up to the isolating switch outside of the bathroom and then up the wall into the shower. The wire is bundled with two other 2.5mm2 wires.

The mains are on a type B Wired Fused Cartridge (awaiting delivery of MCB's to replace cartridges) Wylex unit which is 240V and 60A max rating. The cat no is 404IVY.

Obviously at the mo the MCB keeps tripping after a couple of mins so is it okay to do a straight change to a 50A MCB and upgrade the isolating switch to 50A at the same time or would a 45A MCB be okay due the the run of cable etc or something else?

Any comments would be appreciated.

Thanks

 

[Adam_151]

In the words of Def Lep....

No, No, No

There are no circumstances in which 6mm² PVC/PVC has a tabulated current of 50A, let alone whatever 50A over Cg works out to be....

Anyway, that board will be designed for a max loading of 30A on any fuseway, 45A breakers only fit in if twisted at an angle to get around the thing thats supposed to keep them out....

Looks like you are in need of a new shower circuit and a new board!

 

[luminaire]

Your cable would need to be upgraded to 10mm² as well as the MCB which ought to be 50A, but it is borderline so you might get away with 45A. You haven't mentioned RCD protection which would also be well advised to have.

It may well be in your best interests to have your CU upgraded with a split load board and have your main supply upgraded to 100A rather than 60A. So you would need to ask your supplier.

I would be inclined to get a quote from an electrician, it could be that your system is rather old and there might be other factors that need looking at as well.

 

[CP76]

thanks for your replies. You are both right it is about ready for an upgrade although all the wiring around the house been replaced recently so as much as i hate to spend my hard earned cash i will call in the pro to put in a new CU and upgrade the cable. I can then add to it if needed in the future.

Need to sort it out soon so i can have a decent shower !!

 

[CP76]

just so i dont look stupid when the electrician comes can i just ask if there may be a cheaper alternative to a full cu such as putting in 10mm2 cable and changing the switchfuse to 60A with a 50A MCB if as per the replies infer that the 30A is insufficient.

Apologies if none of this makes sense!

 

[Steve]

That may be a cheaper alternative, the new one will also require an RCD.

If it was installed as a seperate unit to start with though this implies your existing fuse box is past it.

 

[CP76]

many thanks, unless the difference in price is massive will prob upgrade the lot as it prob makes sense to do so if the sparky is already working on it.

 

[Taylortwocities]

Youre electrician could install something like this : http://www.tlc-direct.co.uk/Products/CMP1slash50SH.html

The price is only £20 less than a full split load board - your spark would have to upgrade the bonding etc whichever he is doing.

I'd go for a new board if it were me for many reasons.

 

[Steve]

Contactum. Yuck.

 

[dingbat]

The mains are on a type B Wired Fused Cartridge ... Wylex unit which is 240V and 60A max rating.

... about ready for an upgrade although all the wiring around the house been replaced recently...

Why do those two excerpts from your post ring alarm bells, I wonder?

I long ago lost count of the number of 'rewired' houses I encounter that need, um... rewiring.

 

[Taylortwocities]

I said

......something like this............

.

I happened to be on the TLC site. I agree Contactum not the best.

 

[ricicle]

Contactum. Yuck.

Not being an electrician yourself, can you tell me your problem with the above brand?

 

[RF Lighting]

Have you ever tried fitting one? All will be revealed

 

[Steve]

Not being an electrician yourself, can you tell me your problem with the above brand?

Appearance. Not very nice to look at, is it? I'd far rather have a Hager or Wylex board there.

 

[Taylortwocities]

Jeez you guys are so picky.

Pop one of these in..

Happy now?