Changing wire fuse cartridges for MCB

[chrisbyrd]

Hi All

I'd like to replace the wire plugin cartridge type fuses in our 'consumer unit' with the plugin replacement MCB style ones

I'm a little unsure of what current rating to replace them with though. As far as I can see, they're all 30a except for the lighting circuit which is either 5a or 6a

Its been a while since I checked their current ratings (and i'm not in the house) so I may be wrong with those vlaues

What are the correct ratings for:

- power socket ring mains
- lighting circuit (just 1)
- electric cooker
- electric shower

do I just replace with like for like, or have the guidelines been updated? the current wire type ones seem to be in odd denominations

 

[Spark123]

Things like ring socket circuits are normally 30A/32A, lights 5A/6A. The only thing with replacing these with plug in MCBs is you should have the earth fault loop impedance of your circuits checked as the max for a fuse and MCB is quite different. Also you should look to RCD protecting the socket circuit if it can reasonably be expected to supply portable equipment outdoors, which may be a better call for a CU change if your CU is a standard wylex. Also, please note that this work is notifiable to LABC under part P of the building regs England/Wales.

 

[bootneck]

what changing fuses for mcb's or the consumer unit ?

 

[Spark123]

I would have thought either as the circuit protective measures are affected.

 

[chrisbyrd]

i've got to notify them about changing the fuse for an MCB? That sounds like a bit of a ballache - i'd expect to have to notify them for changing the whole CU, but just swapping fuses for MCB's?

Can anyone confirm?

 

[JohnD]

My superhuman powers tell me you have a Wylex Standard CU.

Is that right?

Is it cream, brown, or grey?

I think if you notify swapping plug-in fuseholders for plug-in MCBs your letter should be framed and put in a museum. It will be the only one ever seen.

 

[chrisbyrd]

is that 30a\32a for shower + cooker too?

my very rusty maths - 9kw shower \ 230v = 39a? does it really draw that much current?

 

[bootneck]

well mines brown, and so is the consumer unit.

 

[chrisbyrd]

My superhuman powers tell me you have a Wylex Standard CU.

Is that right?

Is it cream, brown, or grey?

brown, with a removable 'cover' over the fuse cartridges, held in place with a thumb screw middle top

 

[JohnD]

well mines brown, and so is the consumer unit.

Then it's more than thirty years old and time you replaced it.

 

[chrisbyrd]

i was wondering about replacing the whole CU

what sort of price should i expect to pay for materials+labour to have this brown wylex thing replaced with a new proper MCB CU?

The wiring looks to be in good condition going into the existing CU and there's plenty of length for working with so it should be fairly straightforward

I'd quite like to have a go myself, but i think its probly best to leave this to a pro - especially with all the notification\checking etc

Whats this likely to cost me? 7 or 8 circuits

 

[securespark]

Rule 9......

 

[bootneck]

well mines brown, and so is the consumer unit.

Then it's more than thirty years old and time you replaced it.

the house is only 27 years old !

 

[chrisbyrd]

ah yes - sorry