Rcd vs distributors fuse

[DuncanS]

Here is a little cunumdrum that is probably quite simple. Uk network are coming to upgrade their fuse from a 60A to a 100A so that we can put in another mini consumer unit for a new shower and cooker... The existing consumer unit which serves the house is protected by an 80A RCD with 30mA trip, my question is, should we replace the RCD with a 100A 30mA one or is it satisfactory as the load will be split once the mini consumer unit has been installed? My understanding is the existing RCD can only handle a load of 80A and if the distributors cut out is 100A then we run the risk of burning out the RCD.

 

[telectrix]

i'll grant to duncan the fact that the osg is poorly worded. proof of the pudding will be to fit the bloody cooker. turn it on full whack, then clamp it. after initial 1 minute warm-up, bet no more than 21A ( excluding socket outlet.)

 

[Risteard]

i'll grant to duncan the fact that the osg is poorly worded.

I would agree that it is unnecessarily confusing also.

 

[Rockingit]

But all this is smoke and mirrors, tbh. The OP is clearly trying to do the work himself and doesn't have a clue. The only upside is that he's probably had a bill from the DNO for something that he didn't need to do.

 

[Rockingit]

You are saying your house is 220A with diversity applied, what have you got there??

Not mine, a customers place. Has a 12kW ground source system, four outbuildings, a private water treatment plant, American white goods, illuminated grounds.... and so on. I think the sum total of all the breaker values across 4 DB's is something like 600A. And it's been running very happily on a standard 80A fuse coming from a 22kva pole TX. I've never seen the whole lot pull more than 40ish amps when clamped.

 

[GMES]

I'm sorry but it just doesn't say that.... I tried to upload a picture of the page but Im not sure it worked. Here is the exact quote from the osg printed in 2013... "10a + 30% f.l. Of connected cooking appliances in excess of 10a + 5 a if socket-outlet is incorporated in control unit" I'm not sure how you guys interpret that as all the variations I've so far seen....

I'm sorry but it does say what i said on page 110 you are reading page 111. i am sat looking at it now , 2 diferent tables as Andy as already pointed out a few post's back. Now if your's doesnt say that on page 110 then you have a fake copy there are plenty out there.

Can someone also look this up and confirm that on page 110 it states 30% of remainder
No excuses you should all have your books with you at all times. :toetap05::toetap05::toetap05:

 

[telectrix]

that's not a problem . all he needs to do is buy a fake cooker.

 

[Octopus]

The rules and guidance for calculating diversity are well out of date and need a major rethink. In years gone by the average house had 4-6 fuses.

New builds now can have upward of 10 and my own refurbishment will have 12 when complete. Our house has gas heating and I estimate the maximum demand to be approx. 35A!

 

[telectrix]

when 'er indoors is not cooking , showering, or doing her hair, our house happily draws a massive 3-4A.

 

[GMES]

It's ok for you Tel but our lass as taken out 3 100amp main fuses in a row with a toy of some discription that is to powerful for batteries, I am still none the wiser to what it is.

 

[Engineer54]

Please enough about diversity.

Think you need another 5 weeks at that training centre, because you clearly have no understanding of diversity, or accessing the max demand of an installation. You sure aren't listening to any of the good advice from the more experienced and reputable members here either....

Why you are considering a mini CU for a cooker and a shower is a bit suspect too, especially if your existing CU has only One RCD covering the whole house... Get it changed out for a dual 17th CU that can accommodate these two additional circuits!!

 

[Knobhead]

How about this for diversity:

The grid system allows 2KW per customer for calculating base load.

 

[Knobhead]

Think you need another 5 weeks at that training centre, because you clearly have no understanding of diversity, or accessing the max demand of an installation. You sure aren't listening to any of the good advice from the more experienced and reputable members here either....

Why you are considering a mini CU for a cooker and a shower is a bit suspect too, especially if your existing CU has only One RCD covering the whole house... Get it changed out for a dual 17th CU that can accommodate these two additional circuits!!

Meggerman Mk2?

 

[GMES]

Pmsl Tony I was gonna put the same, you beat me to it. But let's face it I am never gonna be up earlier than you am I!!

 

[Zebra Stripe]

I'm sorry but it does say what i said on page 110 you are reading page 111. i am sat looking at it now , 2 diferent tables as Andy as already pointed out a few post's back. Now if your's doesnt say that on page 110 then you have a fake copy there are plenty out there.

Can someone also look this up and confirm that on page 110 it states 30% of remainder
No excuses you should all have your books with you at all times. :toetap05::toetap05::toetap05:

Hey 'reading' not your strong point then Duncan? You only had to let your eyes wonder slightly to the left to blow your argument clean out of the water.

I'll confirm this Gmes, crystal clear page 110, worded differently in Table A2 to allow text to fit into a one page Table.