Old shower replacement

LeeUK · 23 Aug 2013 at 01:09

I have an old broken 1980s Redring 7kw shower which is connected to it's own 30amp fuse in the fuse box.

Is it safe to replace this with a modern 8.5/9kw shower or does the cable need upgrading aswell?

I won't be doing the work myself, will get an electrician in.

pitchfork · 23 Aug 2013 at 07:43

It would depend on the capacity of the wire.

Gentwee · 23 Aug 2013 at 22:28

Id say no. Firstly a 8.5kw showers normally needs a 40amp fuse/mcb so this'll need updating. I'd guess that your cable is going to be 6mm at most considering it's likely age and current shower rating. AFAIK that is usable for a 8.5kw shower at most depending on how its run (just sat on a wall and it can take more power safely that if it's covered in insulation for instance).

In short it's most likely gonna need a lot of electrical work done so you might as well go the full hog and get a 10kw fitted. Of course a lot of this is just guess work

BTW I'm not an electrician but have looked into this lots.

LeeUK · 24 Aug 2013 at 19:27

Just checked the cable and it is 8mm (I think) either way it's been there 30 years.

The fuse is an old black fuse with 2 prong on with fuse wire in the middle between the prongs. So if the cable is suitable, could I not just get a 40amp rated fuse off the 'bay to swap over?

Nightglow · 24 Aug 2013 at 19:55

LeeUK said:
Just checked the cable and it is 8mm (I think) either way it's been there 30 years.

The fuse is an old black fuse with 2 prong on with fuse wire in the middle between the prongs. So if the cable is suitable, could I not just get a 40amp rated fuse off the 'bay to swap over?

I would seriously consider have your electrics checked first, & your consumer replaced, to bring you up to 17th regs.

Rewireable fuses are old tech nowadays, very slow to react compared to a mcb.

Cable won't be suitable, your looking at 10mm cable minimum, & I certainly wouldn't be using a rewireable fuse in shower today.

Gentwee · 25 Aug 2013 at 09:07

There isn't a 8mm cable (at least not these days) so you'll have 6mm. You really just need to get your electrician to sort this out as there's other variables you have to consider (route of cable etc) and your current setup doesn't sound like it can take anything bigger without being redone from scratch.

As Nightglow said you're going to need 10mm cable with a proper mcb. No electrician will just change your current fuse, they'll either say redo the whole fuse box to the current standard or just install a new mini rcb/mcb purely for the shower.

LeeUK · 25 Aug 2013 at 09:15

Cable should be easy to replace as it comes out the wall from where the fuse box is and goes along the outside wall and into the bathroom again so it should keep work to a minimum. Looks like the shower was installed after the house was rewired back in the 80s.

Might just look into getting a new consumer unit installed too is price is good enough. Don't have enough spare cash for a whole house rewire though.

JohnnyG · 25 Aug 2013 at 09:27

Your electrician is going to have to fit an RCD anyway so it might be worth looking at a new consumer unit instead of just fitting an RCBO or splitting the meter tails.