Shower woes, including 6mm vs 10mm

[SteveDolphin]

Can we have a picture of the whole box?

Sure: https://imgur.com/a/cyvE2

 

[EFLImpudence]

I would say it's 6mm² cable but that is fine as long as it does not run through a lot of thermal insulation.

 

[EFLImpudence]

I'm pretty sure 30A is the maximum rating of fuse/MCB that may be fitted to your box.
Perhaps someone will confirm.

If so -
Very small shower, 7kW or
Separate shower CU or
Replace whole fuse box.

 

[Risteard]

It absolutely definitely is not 10mm^2 cable as the cpc is solid rather than stranded. (It also hasn't been sleeved.)

 

[Echo the husky]

If the shower cable has a single strand for the earth wire it is 6mm² or less.
The fuse box may be have 1 high current way, it is easy to tell if it has as the clips that hold the fuse in the way nearest the main switch will be a very different design to the others. If it is the same as the others then all the ways are maximum 30A. Switch off the main switch if you go to check! I'd post a photo but the various Wylex boards I have here all have max 30A ways.

 

[SteveDolphin]

It absolutely definitely is not 10mm^2 cable as the cpc is solid rather than stranded. (It also hasn't been sleeved.)

No, it's not: https://i.imgur.com/LZF6Kph.jpg

 

[Echo the husky]

The CPC can't be seen in that photo, which is concerning! As it should be earthing that brass plate. Why is all that copper showing?!

 

[SteveDolphin]

The CPC can't be seen in that photo, which is concerning! As it should be earthing that brass plate. Why is all that copper showing?!

Well worryingly when I took off the switch to inspect the cable it came out the back - I've re-screwed it in now...

 

[Echo the husky]

What about the lack of earth to the brass switch plate? Are the earths hidden in the back box? We still haven't seen them!!!!

 

[SteveDolphin]

What about the lack of earth to the brass switch plate? Are the earths hidden in the back box? We still haven't seen them!!!!

There is no earth to the brass faceplate, just to the back box (the cable is there, but it's not attached and clearly never has been.

Which yes, is bad, but the first question was how to fix the shower cutting out, and it sounds like the consensus is 'get it rewired, get a new consumer unit'?

 

[sparkwright]

As the fuse box is of a certain age where the fuseways are likely to be rated at a maximum of 30 amp, if you do have a seperate switch fuse unit fitted, be certain RCD protection is provided for the shower.

Though it would be just as well to replace the whole existing fuse box, this way RCD protection can be provided on all your circuits.

Send a picture of the whole area near the fuse box, it's possible you may have an RCD somewhere protection all or part of the installation.

 

[deadshort]

I would replace the existing CU and the 1950's switch fuse with a new 17th edition CU.


Regards,

DS

 

[flameport]

Cable is 6mm, which could be OK for a 9.5kW shower depending on how the cable is installed.
A 40A MCB would be required for a 9.5kW shower, but that fusebox is not suitable for anything above a 30A.

Options are therefore to either replace the entire fusebox, have a smaller CU fitted just for the shower, or ditch the electric shower completely and fit some other type.
What kind of boiler have you got?

 

[SteveDolphin]

Options are therefore to either replace the entire fusebox, have a smaller CU fitted just for the shower, or ditch the electric shower completely and fit some other type.
What kind of boiler have you got?

Combi, but it'll be a pain to get a hot water pipe to the shower

 

[SteveDolphin]

Send a picture of the whole area near the fuse box, it's possible you may have an RCD somewhere protection all or part of the installation.

Oh there definitely isn't - there appears to be a smaller CU above it with an actual fuse (not MCB) - I don't think it's been touched since the 50s!