Electrical question

[RogerS]

..... Since mine is on a 40 amp breaker, and the sparks would have made sure that the breaker protected the wiring does (how do you know that to be the case ? ) that mean that I am good to go with the upgrade from 8. to 9.5kw? ....

...

 

[Racers]

I never thought of the tolerance in the supply. I wonder what guarantees the power company give?

230 volts
In the UK, the declared voltage and tolerance for an electricity supply is 230 volts -6%, +10%. This gives an allowed voltage range of 216.2 volts to 253.0 volts.

Pete

 

[DrPhill]

..... Since mine is on a 40 amp breaker, and the sparks would have made sure that the breaker protected the wiring does (how do you know that to be the case ? ) that mean that I am good to go with the upgrade from 8. to 9.5kw? ....

...

I guess that that is an assumption, but it was all part of the same job - the consumer unit (and choice of breaker) was installed to supply the shower, and the wiring to the bathroom (including fan/switches etc) was all installed new at the same time. Would that be an unsafe assumption? If so I could begin to doubt every aspect of the job.....

 

[DrPhill]

I never thought of the tolerance in the supply. I wonder what guarantees the power company give?

230 volts
In the UK, the declared voltage and tolerance for an electricity supply is 230 volts -6%, +10%. This gives an allowed voltage range of 216.2 volts to 253.0 volts.

Pete

Thanks. Can we hold them to it?

 

[RogerS]

..... Since mine is on a 40 amp breaker, and the sparks would have made sure that the breaker protected the wiring does (how do you know that to be the case ? ) that mean that I am good to go with the upgrade from 8. to 9.5kw? ....

...

I guess that that is an assumption, but it was all part of the same job - the consumer unit (and choice of breaker) was installed to supply the shower, and the wiring to the bathroom (including fan/switches etc) was all installed new at the same time. Would that be an unsafe assumption? If so I could begin to doubt every aspect of the job.....

Can you not see what size/type of cable is there coming out of the consumer unit or is it all hidden away ? If it were me then I'd be taking off the front cover of the CU and having a decko at the cable.

 

[Jake]

The difference between 6mm and 10mm is pretty obvious if you have seen both before, but if not... The cable clips often have the size on them. The earth conductor will be a giveaway too if you take the CU cover off, 6mm being single solid core, 10mm being stranded.

 

[DrPhill]

Thanks Jake - there is a picture (several posts back) of the cable just before it enters the bathroom, complete with tape measure. Does that identify the cable?

 

[Jake]

I'm not going to guess from a photo. If I were you I'd take the front off the CU carefully (it's safe as long as you don't touch anything) and have a look at the earth wire. All of the earth wires from all of the wires in the CU will all go to one or two banks of earth terminals at the top of the CU like this:

You should be able to see which comes from your cable and it'll be obvious enough if it is stranded or not.

or 6mm solid earth

This is all obviously just to give you a steer on what the sparks will say when he has a look at the installation as a whole and nothing more.

 

[DrPhill]

Plumber has just been and wont change the spec without say so from a qualified electrician - so what I think/find wont matter

So its 8.5kw and no 50 gbp saving.

But thanks for the advice and pictures.

 

[Terry - Somerset]

Somewhat cynically I suspect 8.5kw showers were originally installed as they were confident this would be ok with a smaller size of cable. Overall probably a cheaper installation!

Go up to 9.5kw and the cable becomes marginal - although it seems to depend partly on the length of the cable and how it is routed.

Shower manufacturers know this. I don't expect there is much difference in manufacturing cost between an 8.5 and 9.5kw unit, but for the punter the difference is often the extra cost of new cable installation by a qualified electrician.

£10-50 extra cost on the shower unit is trivial compared to the labour, material and disruption cost of re-cabling!

 

[Racers]

I never thought of the tolerance in the supply. I wonder what guarantees the power company give?

230 volts
In the UK, the declared voltage and tolerance for an electricity supply is 230 volts -6%, +10%. This gives an allowed voltage range of 216.2 volts to 253.0 volts.

Pete

Thanks. Can we hold them to it?

They changed the tolerance to allow us to keep the same voltage (240V) and harmonize with Europe (230V)

Pete

 

[Racers]

Don't forget that the length of cable affects the size of the cable, you need a bigger cable for long runs.

Pete

 

[HappyHacker]

I never thought of the tolerance in the supply. I wonder what guarantees the power company give?

230 volts
In the UK, the declared voltage and tolerance for an electricity supply is 230 volts -6%, +10%. This gives an allowed voltage range of 216.2 volts to 253.0 volts.

Pete

Thanks. Can we hold them to it?

In theory yes, in practice unlikely.
I was at a customers and the supply voltage was 190V at 18:00 but was OK during the day. Tested with two calibrated meters. I told the customer to phone their supplier and complain.

I saw the customer a few months later, they had complained and were fobbed off. I would have phoned myself but the customers parents both had problems and having me working in the house was a problem so I had to work quickly and get out and she did not want to get me involved.

Apparently it took them forever to cook Christmas dinner when all their neighbours were trying to do the same.