Hall/landing lights when planning a rewire

[echoes]

Planning a rewire for a 3 bed house with a High Integrity CU.

RCD1:
Upstairs ring
Kitchen ring (alternatively considering a couple of radials instead)
Downstairs Lights
Garage Lights

RCD2:
Downstairs ring
Upstairs Lights
Cooker
Garage ring

RCBO1
Alarm

No need for shower or immersion right now.

If I have hall/stairs/landing lighting with 2-way switching, is it best to put the hall and landing lights on the same circuit, so that only one circuit need to be isolated when working on a switch (for example)?
Having 2-gang switches controlling power on 2 circuits doesn't seem best.

 

[ban-all-sheds]

Isolating both isn't a show-stopper - how often do you take switches off the wall to fiddle with them?

I guess having the landing light on the downstairs circuit is marginally preferable - then if you lose the circuit you'll still have light available from the upstairs rooms, or if you've lost upstairs you'll still have lighting for the landing and stairs.

Best thing really though is to have the landing light where you'd logically expect it, i.e. on the upstairs circuit, and make it and the hall light emergency ones.

 

[ban-all-sheds]

No need for shower or immersion right now.

Non-RCD circuit for F/F ?
Non-RCD circuit for CH boiler?
Dedicated circuit for hifi?
Dedicated circuit for IT equipment?
Loft?
Outside lights?
Garden electrics?
Shed supply?
A circuit to be supplied by a generator?

 

[echoes]

Thanks b-a-s. I will go for having each light on the logically expected circuit and get the benefit of light in the area when a bulb pops... that's what I did the last time, but I did wonder when I did it if it was standard practice or not.

"Isolating both isn't a show-stopper - how often do you take switches off the wall to fiddle with them?"

Good point: Practically never.

For kitchen sockets circuits, it's clearly better to have a dedicated circuit, and there seems to be a reasonable case for using radials rather than a ring - would you go for radial, give the opportunity presented by a rewire?

 

[flameport]

The RCBO for just an alarm is not required - if something else goes wrong and causes no power to the alarm, it won't matter as they all should have battery backup. If on the same RCD as something else, you are more likely to notice anyway - on it's own RCBO the power could go off, and not be noticed for hours/days/weeks.

 

[ban-all-sheds]

would you go for radial, give the opportunity presented by a rewire?

Every time, and not just for kitchen circuits.

 

[echoes]

Non-RCD circuit for F/F ? Only if I can get the cable to it without requiring an RCD - may well be possible, but careful planning should mitigate. i.e. not putting F/F on same circuit as other large inductive appliances.
Non-RCD circuit for CH boiler? That'll be a FCU on the garage circuit.
Dedicated circuit for hifi? Not needed (and it will move!)
Dedicated circuit for IT equipment? ditto
Loft? Lights off upstairs lights, no sockets needed
Outside lights? Use garage light circuit
Garden electrics? Use garage ring
Shed supply? Not needed
A circuit to be supplied by a generator? Never even considered it! Could add: circuit supplied by meter by-pass (only joking).

Thanks for those suggestions - Possibly a bit OTT in some areas and I have given some thought to them - certainly enough to warrant a CU with some spare capacity.

 

[echoes]

The RCBO for just an alarm is not required - if something else goes wrong and causes no power to the alarm, it won't matter as they all should have battery backup. If on the same RCD as something else, you are more likely to notice anyway - on it's own RCBO the power could go off, and not be noticed for hours/days/weeks

Good point - that's saved me 20 quid off b-a-s's shopping list!
Same argument could be made about non-RCD for the F/F

 

[echoes]

I think one can get a bit carried away with the dedicated circuits. I lived in a place for 10 years with everything on one single RCD, which only ever tripped occasionally when a bulb went and was most happy with the oven, washing m/c, shower, F/F. Must've done a good job with the rest of the installation!

 

[flameport]

Same argument could be made about non-RCD for the F/F

Absolutely - the likelyhood of a properly designed circuit with an RCD tripping off is very small.
Even if it did, if people are in the property and the freezer is supplied from the same circuit as some other sockets, it will be noticed fairly quickly.

 

[echoes]

b-a-s you've made me think hard about radials instead of rings. I'm assuming that one would use 4mm2 protected by a 32A MCB for each circuit. Something like:

Kitchen radial 1 (F/F + most sockets)
Kitchen radial 2 (white goods + sockets)
Downstairs radial
Upstairs radial
Garage radial

Might be an extra circuit, but the ease of installation and testing might result in less blasphemy, and less cable.

 

[ban-all-sheds]

I'm assuming that one would use 4mm2 protected by a 32A MCB for each circuit.

Depends on how the cable is installed.

• http://www.tlc-direct.co.uk/Book/4.3.1.htm
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf
  
  
• http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html[/list]
  
  Apart from the circuit with the D/W, W/M, T/D etc, 20/25A radials will be fine.

 

[echoes]

Thanks for those tips. I don't think I'll have any buried cabling, and the lengths should be fine. Very helpful - thanks!