Consumer Unit Terminology

[wedge69]

Hello,

Before moving into a new house, we got an electircal check done. No major problems, just a few recomendations, one of which was upgrading the consumer unit to a 5x5 split M.C.B, R.C.D unit.

Does the 5x5 imply that there are five slots for M.C.B's and five slots for R.C.D's? Do all circuits need R.C.D's?

Current set up of fuse box is (I think it only has M.C.B's, no R.C.D's):
1) Lights
2) Plugs front
3) Plugs back
4) Cooker
5) Shower
6) Shed

which is obviouslky one more than five....

Cheers

 

[spence_spark]

the 5x5 relates to.... 5 x mcb NON RCD protected, 5xMcb RCD protected
hope that helped!

 

[wedge69]

That's great, thanks.

As a general rule, is there a split between what things should be RCD protected, and which things aren't to important to be protected?

 

[securespark]

1) Lights
2) Plugs front
3) Plugs back
4) Cooker
5) Shower
6) Shed

Lights are placed on the non RCD side, so that if the RCD trips, you are not plunged into darkness.

Socket outlets generally are placed on the RCD side, as they may be used to provide power to equipment used outdoors. Some people wire the downstairs sockets to the RCD side, and the upstairs to the non RCD side, as it is unlikely (but not impossible) that the upstairs sockets will power anything outside.

But you seem to have a bungalow - front and rear circuits?

In which case, I would put both on the RCD. But give some thought to providing a dedicated circuit for any fridges and freezers which would be wired through the non RCD side so that if it trips, you don't lose power to those appliances.

Cooker, some do, some don't.

Shower: most mfrs recommend protecting the shower with an RCD - I would, too.

Shed: Definitely!!!

 

[ban-all-sheds]

The wiring regulations require RCD protection on sockets which might reasonably be expected to supply portable equipment for use outdoors, and on circuits in bathrooms for fixed equipment in other than water heaters and shower pumps in Zone 1, and non-fixed equipment in Zone 3. They are also required in some zones in swimming pool locations, but I'm guessing you don't have one of those...

There's no good reason not to have them on all socket circuits, and although not required in the regs, most people regard fitting them to shower circuits as good practice.

They are not good for lighting circuits, as if it trips you'll be plunged into darkness, electric cookers can cause nuisance trips, ideally you should not have the fridge/freezer on one because you want to avoid the loss of that circuit.

For maximum convenience (at a higher price) you should use individual RCBOs (combined MCB/RCD devices) on each circuit you want to protect rather than a single RCD covering multiple circuits.

 

[wedge69]

Thank you for all your replies, I definately feel more clued up now, and will feel more confident when I get an electrican around to fit it.

In the answer to some things posed above:

a) When I use the sockets in the shed (for the lawn mower and things) I use one of those plug-in RCD things that you can buy.

b) I live in a standard semi. I always assumed that one plug ring would be upstairs, and one would be downstairs. However, when I went to replace a socket facia the other day I descovered this was not the case (I tested the socket I wanted to replace by plugging in a lamp). Turns out the lounge (front of the house) and the front two bedrooms are on one circuitm and the kitchen/diner (back of house) and the back bedroom are on the other ring.

 

[ban-all-sheds]

a) When I use the sockets in the shed (for the lawn mower and things) I use one of those plug-in RCD things that you can buy.

An excellent idea if you don't have proper RCD protection, but not a substitute, as there's no guarantee that you, or someone else, will always do that.

b) I live in a standard semi. I always assumed that one plug ring would be upstairs, and one would be downstairs. However, when I went to replace a socket facia the other day I descovered this was not the case (I tested the socket I wanted to replace by plugging in a lamp). Turns out the lounge (front of the house) and the front two bedrooms are on one circuitm and the kitchen/diner (back of house) and the back bedroom are on the other ring.

Never assume. You did the right thing by testing, and now you know why - finding out the hard way that it wasn't how you assumed could have spoilt your entire day. Now that you know what's what, label the CU accordingly.

 

[Steve]

kitchen ring in our house passed by a bedroom socket above the kitchen, so they put this on the kitchen ring (spurred from a junction box) to save running another cable all of 2 metres from the other socket in the same bedroom. lazyness there.

 

[mapj1]

Laziness, or minimum inconveniecne in event of fault ? at least you can plug the drill in one to work on the other!

 

[Steve]

should have left it as it was and extended the upstairs ring to provide a socket in the kitchen for that purpose too then! ohhh we have cooker outlets for that! and extension leads . . .