Replacing Old Fuses on a CU

[gpc]

Hello,

I have an old CU with cartridge fuses like the ones above in the pic. Can i simple replace with moderm MCB's like this

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=100611&ts=38846&id=48030


Cheers

 

[Adam_151]

Possibly, why do you want to though?

 

[Qedelec]

They are a direct replacement except that you will have to cut the fuses cover to fit.

As Adam said "why would you want to" you would be best advised to replace to the complete board so that you can protect your nearest and dearest with RCD protection.

 

[gpc]

Well,

I am rewiring my kitchen, moving old sockets, moving the cooker switch, adding 2 new ones and fitting some spotlights. I have done all the donkey work, chasing out, fitting the boxes, running the cables etc.

I need someone to come in test and part p sign off, or alternatively, connect, test and sign off. ( preferably without the need for a second mortgage)

The old CU is looking a bit tired and although working OK, i think it would benefit from having the MCB's added, and while i was doing the work in the kitchen i thought i may as well upgrade the fuses.

I am trying to avoid a whole new CU as this would then entail testing af all the circuits in my flat.

Regards
Gpc

 

[Adam_151]

I can't see what advantages you will get with MCBs over cartridge fuses, the only think is that mcbs are easier to sort out when they 'blow' but that really should be a very rare event, mcbs if anything would be an annoyance, as they would trip when a bulb blows.

The cartridge fuses could have been installed because of a too high PSCC for rewireables, these mcbs you linked to 'only' have a breaking capacity of 3kA.

If you had re-wireables, there might be slight justification to change them, because re-wireables don't give that 'close' protection, but not with cartridge fuses.

Either leave the board alone, possibly with the additon of an RCD, maybe one one circuit, or built into selected sockets, or have a spark replace the board with a more modern unit thats got an RCD split config and MCBS

I'll leave ban to cover the part P parts of your post

 

[gpc]

ay be i am confusing you with my definition.

The fuses that are ther at the moment are the ones that have the wire that you replace when it blows.

The reason i wanted to change them is if they blow its easier to flick the switch than to have to replace the fuse wire.

Will get a leccy round to advise. Although, one leccy i have has reound did, if i wanted to, offer to replace the fuses. If its just a matter of removing the old and popping in the new than i can do this myself.


Cheers
Gpc

 

[Adam_151]

Yeah, think maybe some incorrect terms have been used here

for future reference:

cartridge fuses... BS1361

and they fit in carriers like this:

Re-wirable fuses, BS3036 :

 

[gpc]

Theyre the ones. the old re-wireable fuse. Apologies - misled by thepicture and discription on the wesite.

Is it worth replacing the rewirable fuses for the more moder MCB's.

Screwfix do the MCB's for £7 each.

What do you reckon?

Gpc

 

[slippyr4]

Is it worth replacing the rewirable fuses for the more moder MCB's.

I'd say no, it's not worth it. MCB's aren't (on their own) any more safe than fuses.

How often do you fuses blow? If the answer to that is "never", then you'd be wasting your money to change them. If the answer to that is anywhere more frequently than "never", then you really ought to get your wiring looked at. A fuse blowing, 99 times out of 100, indicates a fault.

 

[gpc]

true i suppose.

Lived here for over a year, never had one blow.

 

[Lectrician]

I am trying to avoid a whole new CU as this would then entail testing af all the circuits in my flat.

Changing from a 3036 fuse these direct replacement plugins should also be treated as a new CU, and tested as such, as you are changing the circuit characteristics.

IMO, these plug in replacements are expensive for what you achieve.

 

[just-thinking]

this work comes under building control.ask your local council.
sorry but leave it to a qualfied sparks it will work out cheaper than a funeral.