Diversity factor on rewire

[Percyprod]

Very often DIY jobs are done to a higher standard than those done by so called proffesionals, so let's not go down that road. Any way, I suppose that means none of you would do any work on your car or van, as you're not 'a professional'? Actually what I meant was is it normal practice to fit 2 showers in a cu. I know there is no diversity on their use. As stated they won't be used together. And Mathewd29, if you don't know how to wire and test a shower it's not up to me to tell you!

 

[MJPD29]

I am not having a go at you, and I disagree with your statement about DIY work being better, maybe it is in a very rare case, but more often it is dangerois and potentially deadly. I am not a so called professional, in fact I am a professional.

 

[Percyprod]

My comments wern't aimed at you personally Matthew, I don't doubt you professionalism, nor for electrical work either, but in general a lot of diy do a very good job, whatever it is, and some professionals don't. Perhaps I gave the impression I think most diyers are better, not what I meant. Like I say, many motorists do work on their cars, which is possibly potentially more dangerous than doing some wiring, and they have no mechanical training, but they do as good a job as a garage would. I just don't agree that unless you have the necessary electrical ticket you can't do a safe job that complies with the regs, other than not being signed off.

 

[Resu]

You don't need a ticket, you need to be competent. Your original question proves a lack of competence.

There is a line when dipping into other areas of expertise. I'm sure many people could change the oil and filters in their car without being mechanics but wouldn't try and change a gearbox.

They would likely struggle to do an MOT too without having the right paperwork to back them up!

And Mathewd29, if you don't know how to wire and test a shower it's not up to me to tell you!

Why should it be up to us to tell you how to do it!

 

[Percyprod]

No, but a lot of people would do work on the brakes, suspension etc. I am perfectly competent, it was just a simple question on what other people do. All work I do is perfectly safe. If it is not, then as I have worked to the regs then you are saying they are wrong.

 

[Resu]

No, but a lot of people would do work on the brakes, suspension etc. I am perfectly competent, it was just a simple question on what other people do. All work I do is perfectly safe. If it is not, then as I have worked to the regs then you are saying they are wrong.

At no point did I insinuate the regulations were wrong.

In my opinion you answered your own question in your original post:

because of the available water pressure the 2 showers are never on together.

If this is the case then I see no reason not to have them both on the same board. At the very least I would put them on different RCDs (if it's a split load board), to minimise potential overheating issues as the RCDs tend to be rated at 63/80A. The only time a problem may arise is if/when you come to sell the house.

I'll add that when I was serving my time we completed an EICR on a 12 bed guesthouse (with attached 3 bed owners accomodation). The guesthouse was supplied with a standard "100A" domestic supply. The install was spread over 3 or 4 boards to accommodate various extensions/renovations over the years. There was in total 13 electric showers within the property ranging from 7.5 to 10.5kW! No reports of problems from the owners in the 5 years they'd owned the place!

 

[Percyprod]

Thanks for reply, I wasn't suggesting you'd said regulations were wrong. My point was that whether doing electrics or car repairs, if you do the work to the regulations, or the the workshop manual, and some one says you've not done it right, or that it is dangerous, then they must be saying the regs or workshop manual is wrong. Because that person has no formal qualifications in that subject doesn't necessarily mean it's wrong. And thanks for the point on the split board. I was going to do that. Glad I'm on the right track!

 

[Octopus]

As a homeowner, you are aware of part P. What you are proposing is breaking the law and you know it

 

[Pete999]

Thanks for reply, I wasn't suggesting you'd said regulations were wrong. My point was that whether doing electrics or car repairs, if you do the work to the regulations, or the the workshop manual, and some one says you've not done it right, or that it is dangerous, then they must be saying the regs or workshop manual is wrong. Because that person has no formal qualifications in that subject doesn't necessarily mean it's wrong. And thanks for the point on the split board. I was going to do that. Glad I'm on the right track!

I will take issue on this Percyprod, a Motoring workshop manual is a how to guide, BS7671 the wiring regulations are not, so there is a difference in my opinion.

 

[David M]

Thanks for reply, I wasn't suggesting you'd said regulations were wrong. My point was that whether doing electrics or car repairs, if you do the work to the regulations, or the the workshop manual, and some one says you've not done it right, or that it is dangerous, then they must be saying the regs or workshop manual is wrong. Because that person has no formal qualifications in that subject doesn't necessarily mean it's wrong. And thanks for the point on the split board. I was going to do that. Glad I'm on the right track!

No one is suggesting that you are not capable of doing the installation work. Many experienced competent people are quite capable of doing a good installation job. What is important is that you are able to do the necessary inspection & testing, be fully competent at doing the required tests and procedures and have the knowledge to understand and interpret the results.
You may argue that all the install is brand new and if done correctly will be trouble free. Well in the majority of cases this might be so. BUT the whole point of testing is to make sure there are no faults and that the installation is safe to use. Occasionally even brand new installs have unforeseen problems regardless how much care and attention is taken.
One of my apprentices had just that last week. A brand new install throwing up a high R1 & R2 reading. Turned out to be a "brand new" faulty isolator terminal. If no test had taken place and this circuit was energised it would have been potentially dangerous.

 

[Deleted account]

[/QUOTE]I'll add that when I was serving my time we completed an EICR on a 12 bed guesthouse (with attached 3 bed owners accomodation). The guesthouse was supplied with a standard "100A" domestic supply. The install was spread over 3 or 4 boards to accommodate various extensions/renovations over the years. There was in total 13 electric showers within the property ranging from 7.5 to 10.5kW! No reports of problems from the owners in the 5 years they'd owned the place![/QUOTE]


Hi resu,
I know this is an old thread, but I'm wandering what code you gave the property with 13 electric showers.
The reason I ask is I have been to quote for 7 bed guest house and they have 8 electric showers on one split board CU. supplied by 1 phase. Obviously I would codee C2 for overloading of each of the 63A rcd,s and the 100a rated main switch.

The dilemma I had was the customer asked if the showers are split between 3 boards would it comply. I feel no so would still give a C2 as the main incoming 100A fuse would be overloaded.

There is no visible sign of overheating inside the CU.

I have to make clear I am just at the quote stage and pointed this out to the owner as I was having a quick look to give him an estimate.

I have in the past split 5 existing showers in a guest house and gave it a C3 with a big statement/ risk assessment and advisory attached to eir.
But 8......

 

[Octopus]

C2 for the overload

1 CU , 2 CU's or 3 CU's - that is irrelevant/

 

[Deleted account]

C2 for the overload

1 CU , 2 CU's or 3 CU's - that is irrelevant/

Agreed, thanks murdock.

 

[MDJ]

I'm going to rewire my house, and was wondering if it's ok to have 2 shower circuits as well as cooker, sockets and lights off 1 cu, or would it be better to have 1 of the showers on a separate cu, because of the available water pressure the 2 showers are never on together.

You can put 145 shower circuits in if you like, just make sure your supplied load can cope with them, that aside, don't forget to allow the extra building work you need to be done now, might as well widen all those doorways in your house at the same time so your only making a mess once, at your age it won't be long before your wheel chair will get used more and more

 

[Andy78]

I really can't believe anyone is actually indulging this attention seeking troll once again.