Having kitchen extension to bungalow. I acknowledge 60A 6 way Sentry Consumer Unit needs replacing. Quotes from builders to include that by registered electrician vary between split load or not? Do I need or might as well have split load as being replaced anyways? Thanks
Split Load or not
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Dual RCD or individual RCBO circuits or one RCD and the rest RCBO. Your option
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One RCD is asking for problems, but from 2 to 18 RCD's it all down to the risk of them tripping and what happens if they do trip. All RCD's are not equal some are far better than others at not tripping due to spikes with my 1992 models I do from time to time get a series of trips then it can go for years until the next.
As to if the expensive X-Pole RCD with RCM combined is worth the money I don't know. My mothers kitchen has 4 RCBO's which have never tripped which may be because better quality or because so much less on each circuit.
In the main it is the ring final circuit which cause RCD's to trip so having the ring final on it's own RCD (RCBO) makes a lot of sense. But my caravan has just one RCD protecting all and I have never had it trip so clearly size does matter. So with a two up two down then likely two RCD's are ample but with a mansion then it's another story.
So the problem is we need to divide into circuits to avoid hazards and minimize inconvenience taking account of danger that may arise from the failure of a single circuit such as a lighting circuit. With two RCD's only we put sockets and lights in every room on a different RCD so by using standard and table lights any failure will not result in being plunged into the dark. Where the lights or ring finals are all on one circuit this can't be done so to get more than two RCD's we use the RCBO. Now as to if the circuits likely to cause a trip or the circuits which if they do trip will cause danger are given dedicated RCD protection is open for debate.
To my mind there are two circuits which are rather important one is the lights and the other is the fridge/freezer the rest is only an inconvenience. In my house rather than a dedicated RCD for lights I use an emergency light at top of stairs so with any power cut be it a RCD or whole street I can see to go down the stairs.
I am sure all RCBO is the best option but also expensive. So the two RCD's and two RCBO's is a good compromise. Even one RCD and three RCBO's may make sense.
The fridge/freezer is a real problem. If you used a dedicated circuit with it's own RCBO for fridge/freezer then unlikely it will trip. But if it does trip then you may not notice until too late that it's tripped. To date I personally have not lost the fridge/freezer contains I have always noticed in time. In the main it is the holidays which are a problem as no one to reset the RCD. But with all other items switched off unlikely it will trip during a holiday.
So you have to balance the risk against cost. If you have a consumer unit with two RCD's and two slots for RCBO's even if you don't use any RCBO's if you have problems you can add them latter.
So you have to assess the risk and the cost should you trip a RCD. As long as you have two RCD's then even if it means a long extension lead you can get power to fridge/freezer. You can also swap which RCD any item is supplied from so isolate which appliance is faulty. So many consider two RCD's are enough.
Do remember a RCBO is a RCD so when I say RCD I include a RCBO a RCBO is a MCB and RCD combined.
As to if the expensive X-Pole RCD with RCM combined is worth the money I don't know. My mothers kitchen has 4 RCBO's which have never tripped which may be because better quality or because so much less on each circuit.
In the main it is the ring final circuit which cause RCD's to trip so having the ring final on it's own RCD (RCBO) makes a lot of sense. But my caravan has just one RCD protecting all and I have never had it trip so clearly size does matter. So with a two up two down then likely two RCD's are ample but with a mansion then it's another story.
So the problem is we need to divide into circuits to avoid hazards and minimize inconvenience taking account of danger that may arise from the failure of a single circuit such as a lighting circuit. With two RCD's only we put sockets and lights in every room on a different RCD so by using standard and table lights any failure will not result in being plunged into the dark. Where the lights or ring finals are all on one circuit this can't be done so to get more than two RCD's we use the RCBO. Now as to if the circuits likely to cause a trip or the circuits which if they do trip will cause danger are given dedicated RCD protection is open for debate.
To my mind there are two circuits which are rather important one is the lights and the other is the fridge/freezer the rest is only an inconvenience. In my house rather than a dedicated RCD for lights I use an emergency light at top of stairs so with any power cut be it a RCD or whole street I can see to go down the stairs.
I am sure all RCBO is the best option but also expensive. So the two RCD's and two RCBO's is a good compromise. Even one RCD and three RCBO's may make sense.
The fridge/freezer is a real problem. If you used a dedicated circuit with it's own RCBO for fridge/freezer then unlikely it will trip. But if it does trip then you may not notice until too late that it's tripped. To date I personally have not lost the fridge/freezer contains I have always noticed in time. In the main it is the holidays which are a problem as no one to reset the RCD. But with all other items switched off unlikely it will trip during a holiday.
So you have to balance the risk against cost. If you have a consumer unit with two RCD's and two slots for RCBO's even if you don't use any RCBO's if you have problems you can add them latter.
So you have to assess the risk and the cost should you trip a RCD. As long as you have two RCD's then even if it means a long extension lead you can get power to fridge/freezer. You can also swap which RCD any item is supplied from so isolate which appliance is faulty. So many consider two RCD's are enough.
Do remember a RCBO is a RCD so when I say RCD I include a RCBO a RCBO is a MCB and RCD combined.
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Thanks for all the info – I come from the time when boss called me in to say College (Elc Installation) said you are good lad but showing lack of interest so have a farthing (quarter of old penny) rise but keep it quiet in case the other lads want it 
. Well it got me an extra bacon and tomato sandwich each week. Many many decades back the old MEB registered.
Looked at builders quotes then at Wickes Toolstation and see 2RCD plus 10 mccbs are around £75 – tails less than 500mm plus meter is new type with isolator fitted so no cut service fuse. Existing cables will fit.
To me that’s around £350 – not the £600 quoted by builder but am I being tight?
. Well it got me an extra bacon and tomato sandwich each week. Many many decades back the old MEB registered.Looked at builders quotes then at Wickes Toolstation and see 2RCD plus 10 mccbs are around £75 – tails less than 500mm plus meter is new type with isolator fitted so no cut service fuse. Existing cables will fit.
To me that’s around £350 – not the £600 quoted by builder but am I being tight?
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or even keep it 'quiet'
I'm confused.
How did you get from £75 to £350 and what does the £600 include?
How did you get from £75 to £350 and what does the £600 include?
I wondered, too, but presumed that he got from £75 to £350 by adding on what he thought the labour/time cost should be.
Kind Regards, John
I think 500mm of tails is being pretty optimistic, not that it really matters in the grand scheme of things
Hi sorry for confusion. My guess estimate: Materials: C/U + tails + E bond to both G/W less than 2 mtrs away + odds = circa £ 100 plus 250 labour =£350.
£600 is for CU 10 way. Once decided what sockets etc go where will be further costs - cable runs protection devices etc.
Ideally we want CU fixed up so we can carry on in what is a seperate room but it might be a lot more cost effective to have it all done in one go after getting my own quotes in rather than builders mates?
£600 is for CU 10 way. Once decided what sockets etc go where will be further costs - cable runs protection devices etc.
Ideally we want CU fixed up so we can carry on in what is a seperate room but it might be a lot more cost effective to have it all done in one go after getting my own quotes in rather than builders mates?
Two very important bits you have missed off here.
Well for a new consumer unit the whole range of tests should be conducted for the CU itself and each circuit - not sure how many circuits are involved or their type.
There is also the time to complete the Electrical Installation Certificate and complete the LABC notification.
Then there are the cumulative costs of vehicles, testers and Scheme Costs etc to be calculated in.
And finally there is a profit to be made.
The OP may well believe £350 is a fair cost and in some areas of the country that may be so. He may feel that he can do it for that amount of money.
But of course he will have to add the £250 or so that his LABC might charge him for the privilege.
It does annoy me when people moan about the cost of a project - if they are dissatisfied with the price then get additional quotations - simple.
Incorrect: i asked if 350 was being mean. The issue we have is getting some kind of consistanty in various trades. The same job quote can vary easily by 50% . So is the bottom end too cheap as most often you get what you pay for or is the top end a rip off?
That was my point - they are all essentially 'labour' (time) costs (certainly not 'materials'!). Whether the OP made a reasonable estimate of the total amount of time involved in all the activities and/or accounted for that time at a reasonable hourly/daily rate, I haven't a clue.
Indeed, but those are all elements which would normally go into the determination of the hourly/daily rate, rather than being charged separately on top of an hourly rate, aren't they (certainly in any walk of life I've functioned in - if I tried charging for facilities, registrations, insurance etc. etc. and (IMO, the best of all!) 'profit' on top of my hourly/daily rate, I think I'd get some very interesting responses!). However, as above, whether the OP has made reasonable assumptions, I haven't got a clue.
I agree - but the OP is asking questions about it here, and did effectively acknowledge that he might be "being tight" by suggesting the £350 figure and also for suggesting that the £600 one might be excessive. He is therefore attempting to learn what would be reasonable - although, as always, those here who have not seen the job could probably offer only limited guidance.
Kind Regards, John
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