Planning Re-wire Consumer Unit Size

[bjnorris]

Hi,
I'm planning the re-wire of my bungalow I'm getting a qualified sparks to do the work. I'm going to be doing all the chasing and running any draw lines in for ready for him.
Im thinking of having a full RCBo consumer unit and have listed what I think is required! does this look ok or is it overkill? have I missed anything?

1/ Main Ring Main
2/ Kitchen Ring Main (to cover 6 skts, + Dishwasher, Cooker Hood, Freezer
3/ Double Oven (Radial)
4/ Induction Hob (Radial)
5/ Main Lighting
6/ Kitchen / Dinning Lighting
7/ Utility Room Radial (1 dbl skt + Washing / Dryer / Chest Freezer)
8/ Outside Worksop (Radial)
9/ AV / Study (Radial)
10/ Alarm / Smoke Detection (Radial
11/ Outside security wall lights x 6 (radial)
12/ Bathroom Extractor over ride + Mirror light/Demister ?

Seems like a lot of circuits? & Rcbo's are not cheap!

Regarding the security lighting is it ok to run T&E cable around the loft and just drop down from the eves the 6-8 inches to each of the lights?

 

[ban-all-sheds]

Hi,
I'm planning the re-wire of my bungalow I'm getting a qualified sparks to do the work. I'm going to be doing all the chasing and running any draw lines in for ready for him.

Does he know that, or are you assuming that it will be OK to present him with a fait accompli?

Im thinking of having a full RCBo consumer unit and have listed what I think is required! does this look ok or is it overkill? have I missed anything?

//www.diynot.com/wiki/Electrics:How-many-sockets-and-circuits-should-I-have

1/ Just the one?
2/ How do you know that a ring final is appropriate?
3/ 4/ Why have them on separate circuits?
8/ What accessories will be in the workshop?
12/ Why a separate circuit?

Rcbo's are not cheap!

Nor are they expensive these days.

Regarding the security lighting is it ok to run T&E cable around the loft and just drop down from the eves the 6-8 inches to each of the lights?

It's a bit tacky.

 

[AndyPRK]

Put util and study on the main ring
Unless its a big util.

Mirrors and fan don't need it's own circuit.

 

[ericmark]

I went to my sons house where he had a large consumer unit around 16 I think but at the moment everything is being run from one 16A MCB with extension leads throughout the house. Clearly temporary but point is we don't NEED half the circuits we install.

There are some critical circuits which really it would be better if on their own RCBO for example the lights and fridge/freezer and having the sockets on RCBO protection does stop a fault on a plugged in appliance causing others to trip.

However if I was wiring my house I would use a standard double RCD box and replace on RCD with an isolator so half with RCBO and half with RCD.

What I have questioned many times is why do we fit a kitchen ring? What load does it have? Fridge, Freezer, Kettle, toaster, dishwasher, mixer, bread maker out of all them there are only two items giving a high load and they will only give a high load for a short time.

For a Utility room with tumble drier and washing machine yes heavy load but kitchen not really.

The question is with all RCBO should one trip how long before you realise it has tripped? When my RCD trips I know it's tripped as the landing lights comes on.

My freezer motor when faulty and I was surprised within 4 hours items in the top had started to defrost even with a full unit. They claim 12 hours but that was not the case.

Should my second RCD trip then often takes me longer to notice. At one time I had an emergency torch which would light with power cut but batteries now gone so just don't notice.

 

[ban-all-sheds]

The question is with all RCBO should one trip how long before you realise it has tripped? When my RCD trips I know it's tripped as the landing lights comes on.
.
.
.
Should my second RCD trip then often takes me longer to notice. At one time I had an emergency torch which would light with power cut but batteries now gone so just don't notice.

There aren't many circuits where not noticing they've failed until you go to use them is a problem. Fridge/Freezer, medical equipment (unusual), sump pumps are all I can come up with where you'd really value an alarm. There may be other instances where it's a nuisance, such as getting home and finding you've got no heating or porch light, but then only if you had been at home when the circuit tripped and could have done something if you'd known. And there may be others which are a problem because you've not done proper battery management, such as smoke or burglar alarms.

But basically there are so few that using off-the-shelf monitors/alarms should be perfectly feasible.

 

[JohnW2]

1/ Just the one?

That was also my first reaction - but then I thought that, in a bungalow, to have just one general sockets circuit (with separate provision for kitchen and utility room) is probably not unreasonable.

Kind Regards, John

 

[flameport]

You do not say what size this bungalow is, but from the list given:

Rings are vile - avoid them.
A double oven and hob can be supplied from a single circuit. In terms of loading, it's no different from a freestanding cooker.
Alarm and smoke detectors do not require their own circuit, and certainly for the smoke detectors, they would be better on one of the lighting circuits so that mains failure will be noticed quickly.
Bathroom extractor & mirror do not need their own circuit either, and should be supplied via the lighting.

For the 'security' lighting, hopefully you were not considering those horrid halogen affairs with the PIR built in?

 

[bjnorris]

Yes the Sparks is happy that I do the chasing out and run some draw lines.
As i'm taking down walls and moving them about. it may be a while before all the re-wire can be done, so I'm running lines back to the loft as I go.

The new kitchen, dinning room and utility room is going to be in what was a separate granny annex and it what I'm working on converting now, so it will be re - wired first along with a new consumer unit.

Anyhow after reading all the comments maybe I don't need so many circuits
I'm guessing the Kitchen / dinner and utility can be on one circuit ?

The double oven & Induction hop on another ( they will be next to each other)
and I guess he could fit a double isolator switch?
Does the workshop need it's own circuit? it will be 20ft away from the house and fed by a buried amour cable. just a few power tools and lights?

The bathroom extractor fan needs to work of the light circuit and I guess the mirror lights and demistor can as well?
The study / AV room can come off the main circuit
That just leaves the Main ring two lighting circuits and a alarm/smoke circuit

1 Kitchen / Dinning / Utility room ring?
2 Kitchen / Dinning / Utility room lights
3 Oven & Hob
4 Main ring with spur to workshop?
5 Lights
6 Alarm / Smoke

Outside wall security lighting,, separate or on the lighting circuit?

I know the sparks will know what's what and will provide all the right cable sizes, isolators etc, but I just need to know that it's what I want or think I want Or if there is a better way of doing things. I don't want to go for overkill but also want to be future proof. I did train as a spark 40ys back but changed to communications and networks so I'm also running cat6 and coax everywhere as I plan to instal a HDbaseT system for TV & internet in all rooms

All advise appreciated.
brian

 

[bernardgreen]

Outside wall security lighting,, separate or on the lighting circuit?

Separate, a faulty outside lamp ( rain ingress, hit by football etc etc ) would other wise take out the lighting circuit.

 

[bjnorris]

Outside wall security lighting,, separate or on the lighting circuit?

Separate, a faulty outside lamp ( rain ingress, hit by football etc etc ) would other wise take out the lighting circuit.

Nice one. I never thought of that. thank you

 

[AndyPRK]

Is this CU just for the annex then or the whole bunglow?

 

[Jackrae]

You could take the outside lights from the lighting circuit via a double pole switch unit. That way, if you get a leakage trip the DP switch will isolate both live and neutral faults.

 

[bernardgreen]

You could take the outside lights from the lighting circuit via a double pole switch unit. That way, if you get a leakage trip the DP switch will isolate both live and neutral faults.

Provided you can find the double pole switch unit in the dark and then find the consumer unit to reset the RCBO.

 

[bjnorris]

Is this CU just for the annex then or the whole bunglow?

It will be for the whole of the bungalow. I'm thinking he will either run a temp feed to the new CU or put the new kitchen circuit and two existing circuits on temporary? however judging by how the bungalow is currently wired (No ring, just spurs and spurs off spurs all surface mounted) the rcbo's may keep tripping.
The annex / New kitchen currently has it's own feed to a 1950's CU hanging off the wall! It's hard to believe that this place was a rental and the annex a holiday let. (lights flicker switches crackle and one of the double sockets only works on one side.)

If I can just have the one feed to the Double Oven & the Induction hob, what sort of isolator switch could be used? I guess the cables are going to be rather on the large size?

 

[AndyPRK]

A 45A can be used for cookers