Which Consumer Unit?

[dogfonos]

Appreciate any guidance/advice from experienced electricians.

I intend to employ an electrician to replace an existing domestic CU (circa 1970 ish) because it's run out of 'ways'. Generally, what factors need to be considered when choosing a new CU?. I know that a good electrician will give guidance but I'd like a basic understanding first.

In the distant past, I've heard that some domestic appliances/electronics are prone to tripping both MCB's and RCD's (e.g. equipment with large toroidal transformers) even though there's nothing wrong with the appliance. Is this true?

 

[holmslaw]

..

 

[JohnD]

Get a CU with plenty of unused ways. A 22-way or 24-way will cost little more than an 8-way, because you are mostly paying for a plastic box full of fresh air.

If you can afford it, have the circuits protected by RBCOs. This gives each individual circuit its own combined RCD and MCB. It might cost an extra £30 or so per circuit. If you can't afford that, have at least the freezer, burglar alarm, outside sockets and stair lights on RCBOs. This minimised the risk and inconvenience of having them go off due to a fault on an unrelated circuit. Outside circuits are particularly prone to RCD trips, mostly due to damp and rain penetration or corrosion.

 

[dogfonos]

Thanks holmslaw & JohnD. Two good points I hadn't considered before.

I have identified a current need for a 9 way CU (currently only 6) but will get a few more for possible future expansion. I can see that by using RBCO's, I'll be tempted to introduce more 'ways' and possibly start splitting some circuits.

Any more food for thought out there?

 

[JohnD]

this many

View media item 1090
View media item 1091
View media item 1092

 

[EFLImpudence]

The bottom one is the 'NEW ENERGY SAVING' model.

 

[riveralt]

I have identified a current need for a 9 way CU (currently only 6) but will get a few more for possible future expansion. I can see that by using RBCO's, I'll be tempted to introduce more 'ways' and possibly start splitting some circuits.

Any more food for thought out there?

Yes the conversation is getting worrying like "I" rather than (s)he (the electrician) doing this work.
By all means thinks about it but you will need to discuss these issues with the electrician.