Size of Consumer Unit - too many circuits? Potential to reduce quantity?

[Bucks_Refurb]

Hi

I will be procuring the services of a qualified Electrical Contractor, in the meantime would grateful for some preliminary advice re. draft list of circuits, i.e. strict requirement for dedicated circuits versus potential for number of circuits to be reduced. Am keen for Office to be fed via dedicated circuit as linked in my business. Many thanks.

1 - Downstairs Sockets
2 - Upstairs Sockets
3 - Kitchen Sockets
4 - Downstairs Lights
5 - Upstairs Lights
6 - Oven & separate Induction Hob
7- Bathroom UFH
8 - Boiler
9 - Megaflo/Immersion
10 - Office Sockets
11 - HVAC
12 - House Alarm
13 - Smoke Detectors
14 - Garden Sockets

 

[EFLImpudence]

There are no requirements for dedicated circuits - dedicated just means specifically designed for whatever you want and don't have large loads on socket circuits.

1 to 6, 9 & 10, the rest could all go on other circuits.

It is up to you.

 

[jg321]

And if you're worried about "shared fate", then all RCBO is the way to go. With a dual RCD board you can split the circuits across as many MCBs as you like; the thing most likely to trip and take all the associated circuits out at once is the RCD.

Apart from kitchens, socket circuits these days use very little, and I expect a 20A radial would suffice in most situations, from a load perspective that is. Having one per floor on a dual RCD board addresses the shared fate as I mentioned above.\

Edit: to qualify - I'm not a qualified spark - just a keen DIYer.

 

[OwainDIYer]

What is HVAC? A gas combi boiler and thermostat or kilowatts of heat pump with high starting currents?

Smokes are better on the downstairs lights circuit so a failure is noticed more quickly.

 

[JohnW2]

Smokes are better on the downstairs lights circuit so a failure is noticed more quickly.

I agree - and the alarm could also go on that circuit (or possibly the downstairs sockets circuit, probably via an FCU).

Kind Regards, John

 

[chivers67]

I'd have a small circuit dedicated for the Alarm don't want that on an RCD and going off in the night

 

[EFLImpudence]

Heating, Ventilation & Air Conditioning.

 

[EFLImpudence]

I'd have a small circuit dedicated for the Alarm don't want that on an RCD and going off in the night

Cos that would stop them going off in the night while they were going off in the night.

 

[chivers67]

Yeah silly me! Battery back-up and all that!

 

[chivers67]

Actually reminds me off a job I did two years ago. Three phase board had an MCB that hadn't made properly and when we switched it back on after installing Heat Pump circuits it wasn't Powering the alarm and it went off in the middle of the night - we didn't have access to check all circuits in the house were back on Ok.

The house was a £3,000,000 mansion in St Georges Hill Weybridge. Oops!

 

[JohnW2]

Heating, Ventilation & Air Conditioning.

I imagine that Owain knew that. However, as he implied, that could represent anything from a trivial to a massive load - hence, I imagine, his question.

Kind Regards, John

 

[Adam_151]

Reset an RCD on a split load board in office of a shop once, the alarm panel which had been without power since the previous day, powered up, decided it didn't know wtf was happening and went into alarm and set off the smoke fogger (separate supply) and then consequently set off the fire alarm. Later found out that it had also triggered the fogger in the night when the batteries first went flat and when the staff saw the fog in the store after lifting the shutter they called the fire brigade.

Always irks me to find domestic type kit installed in commercial jobs, the intruder alarm sharing an RCD with the tea room sockets is asking for trouble, normally residual currant based issues (they fall off the currant buns and bridge the nichrome heating wire in the toaster to the case)

 

[JohnW2]

Reset an RCD on a split load board in office of a shop once, the alarm panel which had been without power since the previous day, powered up, decided it didn't know wtf was happening and went into alarm and set off the smoke fogger (separate supply) and then consequently set off the fire alarm. .... Always irks me to find domestic type kit installed in commercial jobs, the intruder alarm sharing an RCD with the tea room sockets is asking for trouble, normally residual currant based issues (they fall off the currant buns and bridge the nichrome heating wire in the toaster to the case)

Tea-room sockets tripping an RCD, which is subsequently reset, is really no different (as far as the alarm is concerned) from a brief power cut.

Should alarms (whether 'domestic' or 'commercial', and whether installed in domestic or commercial environments) really be such that they go crazy in the event of a power cut?

Kind Regards, John

 

[Adam_151]

Tea-room sockets tripping an RCD, which is subsequently reset, is really no different (as far as the alarm is concerned) from a brief power cut.

But thats not what happens, John. The power gets tripped out in the tea room, no one notices anything else not working, so they phone up and log a support ticket for loss of power to the tea room, the operator logs it as quite a low priory as it is not affecting trading operations (and of course, its not his access to coffee thats been interupted!). Backup battery drains in the panel before anyone is dispatched to investigate and find the tripped RCD.

And sometimes its better that that don't touch the dis-board, seen a case where there is been a damaged cable with a solid short on it, where the breaker has also been knackered... why... bearing in mind this was a fast food place and staffed by a generation who are smart phone obcessed... they thought they'd keep trying to reset it to see if it would start working!

 

[JohnW2]

But thats not what happens, John. The power gets tripped out in the tea room, no one notices anything else not working, so they phone up and log a support ticket for loss of power to the tea room, the operator logs it as quite a low priory ....

Fair enough - those are valid practical/operational issues - but would not that same series of events occur even if the alarm were not powered from that circuit (people would probably be upset about not being able to make tea/coffee!).

In any event, I made my comments in relation to ...

Reset an RCD on a split load board in office of a shop once, the alarm panel which had been without power since the previous day, powered up, decided it didn't know wtf was happening and went into alarm and set off the smoke fogger (separate supply) and then consequently set off the fire alarm ...

.... which, as I said, is surely not how one wants/expects any alarm (commercial or domestic) to behave when power is restored after a period without power (like after a power cut), is it? Admittedly in the domestic situation one would not usually have foggers, but one still would not want the alarm to 'alarm' when power was restored, would one?

Kind Regards, John