New shower cable

[roundthebend]

Hi

We've had a few problems with our shower electrics. It's an over-the-bath type, Redring I think, and it is probably an 8.5kW unit. It's very old so will get replaced at some point anyway.

Anyway, the problem is that after prolonged use (i.e. when 2 or 3 people use the shower back-to-back) we start to get this odd fishy smell. Sometimes, the fuse burns out too so I have to replace it. The fuses are 30A. I looked into getting a breaker type fuse but they won't fit inside our old fuse box so it would involve some cutting.

I believe our cable is 6mm diameter which might be the cause of the problem. So, I'm considering replacing it (or having it replaced).

I appreciate that this job requires someone who knows what they're doing and I'm probably not knowledgable enough. However, I've had a quote from an electrician and it was more than I was expecting.

The fuse box is at the bottom of the stairs. The bathroom is directly above it, with one end of the bath directly above the fuse box. The other end of the bath (with the shower unit on) is against a wall. The pull cord isolating switch is beside the bath at the same end as the shower unit.

So, the cable needs to travel 0.5m into the bathroom floor, then along the floor under the bath (I'm guessing it'll be under the floor boards for safety), then up the wall into the bathroom ceiling/loft, then down to the pull cord. Another cable will run from the pull cord across the wall and into the shower unit.

I estimate this being about 7m of cable.

Looking at various suppliers, I think a 10mm diameter cable for that length should cost about £25. The difficulty is going to be running the cable so it might take a couple or 3 hours. I'd have thought £75 should cover the labour.

Does this sound like a reasonable expectation? Too high, too low? What important points have I missed?

 

[ericmark]

I think you will find cost is not to replace cable but to up-grade the rest of the installation to allow the work to be done under current regulations.

 

[Zambezi]

I think you will find cost is not to replace cable but to up-grade the rest of the installation to allow the work to be done under current regulations.

Agreed - there is more to it than pulling in a new cable (how much more will depend on what state your existing installation is in).

 

[roundthebend]

OK, what does that mean?

What needs to be upgraded? The fuse box is fine I believe, although a breaker-type fuse would be a sensible option but wouldn't need to be a complete replacement of the consumer unit.

So, the only other components are the cable, the pull cord and the shower itself. What have I missed?

 

[Zambezi]

RCD, protective bonding, equipotential bonding, meter tail and main earth sizes, time for carrying out inspection and testing + time taken to fill in the certificate + notify the job to the Part P bods.....

 

[ban-all-sheds]

Hi

We've had a few problems with our shower electrics. It's an over-the-bath type, Redring I think, and it is probably an 8.5kW unit. It's very old so will get replaced at some point anyway.

And when you do you'll probably want a more powerful one.

Anyway, the problem is that after prolonged use (i.e. when 2 or 3 people use the shower back-to-back) we start to get this odd fishy smell.

From where? That smell is indicative of something plastic overheating.

Sometimes, the fuse burns out too so I have to replace it. The fuses are 30A.

And the current drawn by an 8.5kW appliance is.....?

I looked into getting a breaker type fuse but they won't fit inside our old fuse box so it would involve some cutting.

1) It would involve more than that.
2) Your fuse box might not be able to take a device of more than 30A anyway, i.e. it's not rated for it, and could catch fire (yes, really - it does happen) if you try.

I believe our cable is 6mm diameter which might be the cause of the problem.

6mm² csa for the main conductors, not 6mm diameter

So, I'm considering replacing it (or having it replaced).

Good idea.

I appreciate that this job requires someone who knows what they're doing and I'm probably not knowledgable enough. However, I've had a quote from an electrician and it was more than I was expecting.

Then get more quotes so you can establish what the going rate is - as you say, you don't know what's involved. What details were on the quote, i.e. what did he propose to do?

If you're in England or Wales this is notifiable work, so make sure you use a registered electrician.

Looking at various suppliers, I think a 10mm diameter cable for that length should cost about £25. The difficulty is going to be running the cable so it might take a couple or 3 hours. I'd have thought £75 should cover the labour.

Does this sound like a reasonable expectation? Too high, too low?

Too low, IMO.

What important points have I missed?

Pulling the service fuse, providing and installing extra tails and a henley block, providing and installing a shower CU with RCD, checking and if necessary upgrading the earthing and main and supplementary bonding, testing and certifying the work....

 

[holmslaw]

..

 

[roundthebend]

The technical info I've given is just relayed from the electrician that quoted. I suggested that we'd want a 10.5kW unit in future and the 10mm² was recommended. (Yep, I should have said cross-sectional area previously, not diameter). Actually, that diameter was recommended for our 8.5kW shower but it would allow a future upgrade to a 10.5kW shower too.

I'm also aware that the work would need to be certified so an electrician would be required in some capacity. I wasn't proposing to do the work myself but just trying to work out how the cost can be so high when the parts shouldn't be more than £40 and the labour wouldn't appear to me to be more than 3 hours work.

With all the info you've just provided, I can understand more about what's involved and appreciate what I'd be getting for my money.

My only concern now is the consumer unit. I asked the electrician if we'd need a new one, and he said it's not required so to wait until we can afford to have it replaced.

The electrician is a good friend so I've no reason to doubt him. I was simply surprised and didn't want to give him the wrong impression by asking all these questions. Y'know, it could come across as quite rude!

Thanks.

 

[ericmark]

Under current regulations, any new work at least must have an RCD to protect all supplies including lights going into a room with bath or shower. Together with new rules on cables buried in walls this with old fuse boxes will often mean the electrician will recommend a consumer unit (Was called fuse box) change.

There are other options as to how a RCD can be fitted but it is often near impossible to get fuses over 30/32 amp for the older boxes and by time a new isolator is fitted to give single point isolation and a mini consumer unit for shower alone there is very little saving.

The problem however is when fitting RCD’s this can high light other faults in the house.

In theory we should have our houses inspected and tested every 10 years or less and as a result the theoretical house will have been gradually up-graded over the years but of course in practice this does not happen.

In the past electricians have been able to turn a blind eye and do just what you want but now we have “Part P” and any electrician who cuts corners could lose his registered status, which in turn would mean every time he wants to do Part P work he would need to pay council £100.

In real terms, the Labour government instead of giving the Union back its powers has created new institutions to replace them who have powers to remove the licence to work for any naughty boys. Unlike the Unions who traditionally controlled the trade until Thatcher stopped, them these new organisations are profit making.

So don’t blame the Electrician for the £500+ bill it was not his doing. We have to follow the new laws and if a 20mph speed limit means it takes longer then you pay.

If your good friend does not do all the work required he is taking quite a chance and if he gets caught you will be one good friend less.

 

[roundthebend]

Thanks eric.

I've made it very clear to him that I don't want him to do anything to cut the price unless it's legal and keeping within the rules, regs and recommendations.

So it could be that finding a 45A breaker for our fuse box isn't possible? I'll check with him on that. Maybe we'll just get the CU replaced while we're at it. I was hoping to wait a wee while so the money could be put aside for that but if needs must.

 

[ban-all-sheds]

So it could be that finding a 45A breaker for our fuse box isn't possible?

It almost certainly won't be. Is yours a 4 or 6-way, with rewirable fuses? Can you see a rating for the main switch anywhere?

I'll check with him on that. Maybe we'll just get the CU replaced while we're at it. I was hoping to wait a wee while so the money could be put aside for that but if needs must.

Is there space alongside the existing CU for a new one?

Maybe a good compromise would be to have a full-sized CU installed but just put the new shower circuit on it for now. It wouldn't cost a lot more than a mini shower unit, but none of it would be a wasted investment, as you could then have it fully populated when you have the old fuse box replaced.

 

[ElectricDunc]

I'm going to make some assumtions here so please don't shoot me down if i'm wrong, i'm just offering a worst case scenario based on what is possible. Firstly, i wouldn't be surprised if the fuse board was an old timber backed Wylex unit if we're talking about rewirable fuses. These boards will not take a fuse over 30A as it will melt the board plus as your fuse board is made of a flammable material no new circuits can be taken from that board as it does not meet current regulations. Again if it's a rewirable fuse arrangement your unlikely to have RCD protection which again would require a new consumer unit for your shower (easiest way of meeting regs IMO). Plus if the lights aren't RCD protected in the shower room supplimentary bonding will be required and there is also the possibility that your main equipotential bonds (gas, water, oil) may not be up to regs so would also need renewing. These are all possible scenarios and would explain why the quote is what it is.

 

[ban-all-sheds]

as your fuse board is made of a flammable material no new circuits can be taken from that board as it does not meet current regulations.

Which wiring reg says that?

 

[ColJack]

421.3?
421.6?

would either of these cover it?

I submit to you that a fuseboard filled with re-wireable fuses is likely to emit arcs, sparks or particles when a fuse blows.. though whether this can be deemed as "normal use" is debateable..

 

[flameport]

Wooden back or not, the fusebox is probably seriously damaged already from the overheating fuse.