Consumer unit upgrade & requirement for RCD-free circuit

[Scott]

That I never knew. Interesting.

[Andy Burns]

That's at full load

If you're running half a dozen circuits flat out all year, even if they are only 6A RCBOs I suspect you'd be more worried about the £10K bill than the £14 ...

[Scott]

That changes the perspective. Some of my circuits are minimal or no load some of the time.

I certainly would :-)

[Fredxx]

I would have thought the electronics would take nominally the same power independent of load.

There will be additional resistive losses, that you would get from a fuse or MCB simply from using internal conductors and coils of a finite cross-sectional area.

2W over the year would be ~20 units, so if a CU had a fair few that does start to cost money even with no load.

[Sn!pe]

Is that dissipation due to something other than just contact resistance I^2.R loss?

[Scott]

I have eight.

[SH]

Is that all????? I have sixteen......

[Scott]

I'll remember that if I move house.

Have you done it the German way with radial sockets?

[Chris Green]

We have a 16-way all RCBO CU, 14 are in use. It's a large[ish] house but not enormous. In addition to the above there's a 16-way CU out in the garage supplying all the garages and garden.

[Owain Lastname]

I don't know how big this house is but the meter cupboard must be bigger than my bedroom.

Owain

[Theo]

That looks like a European install, where you get three phase as standard. And then they have a thing where lighting etc is controlled via relays/dimmers in the CU - those are the black modules on the right side of the panel. Then you have loads of radials. And it looks like every circuit is controlled by a double or triple-width Hager module (triple for 3 phase presumably).

Oh, the OP says: Not as big as you'd think lol. Its just, Domotics (Niko home control), electric blinds, toggle-able outlets, solar panels, heating pump, 2 ovens, ... takes alot of space.

so there's more control stuff in there as well.

Theo

[SH]

I want one!!!!!

[Adam Funk]

(I meant measures to be taken in advance of the electrician starting the replacement.)

Any suggestions for this bit?

Also, do I want Type C for the lighting circuits?

That's useful to know (about the fridges) so it will probably be a good solution. How many RCCB circuits can you fit in a domestic consumer unit in the UK now? (We currently have 8 circuits across two CUs, then the additional two you suggest, and I would like to have room for future expansion.)

[SH]

You can get Curve 18 way 100A consumer units with a 100A isolator already.

Just fill with RCBO's (I have 16 in mine and room for 2 more)

So you could replace all of your current consumer units and still have room for expansion

[Andy Burns]

Unlikely, the only time I've had to switch to C-curve MCBs was a 42U rack chock full of UPS, servers and disk shelves ... load was spread over four 32A MCBs, but after the fortnightly generator test there was a tendency to trip the non-UPS breakers as mains was restored; staggering the turn-on delay of the servers didn't help as it was the PSUs charging their capacitors which happened whether or not the server was running.

[Andy Burns]

Probably allow 3 more ways for a two pole SPD plus MCB to protect it, sounds like it's easier to fit one regardless of your preference, rather than jump through the hoops to demonstrate you don't need one.

[John Rumm]

Probably not much...

If the circuit will support mains halogen filament lamps or lots of linear fluorescent tubes then yes, otherwise not so much of an issue these days.

Many brands now have single module wide RCBOs, so you can fit as many as you would normal MCBs.

[Theo]

General working area stuff - make a clear space around the CU, stop the dog nibbling their backside, etc.

It helps if you can unplug everything from your sockets, since that makes ring testing easier. (Switching off at the socket might not be good enough if they're only single-pole switches)

RCD trips are because there's a low current path to earth, which typically means the insulation on some powered component (motor, heating element, etc) is on the way out. You might think of those as a warning that an appliance is not in the best of health. Putting things which could be costly to lose power on their own separate RCBO sounds like a good plan.

You can go up to 21 ways in single height or 40 ways in a double unit:

there's no reason you can't stack further CUs if you want to. If you go up to commercial you can get 24 way 3-phase boards which means 72 single phase ways.

Theo

[ARW]

So less than the MCBs according to that link.

[Adam Funk]

Thanks.