Retro fit MCBs for old style CU

[Speedy471]

Hi, I recently had to rewire a fuse in my old style consumer unit, and stumbled across a product by wylex called a retro fit MCB. I didnt have time to look at the packaging in detail, but I got the impression that it can just slot into the place of the existing fuse block and give the benefits of not having to use fuse wire. My question is how easy it it to install these MCBs is it a case of just pulling out the old fuse and slotting them in, or does it involve delving a bit deeper into the fuse box and making wiring adjustments.

Other than that are these thought of as a better alternative to the old style fuses, and do they have the benefits of the MCBs found on the new consumer units.

Thanks

 

[equitum]

First you would need to isolate the CU., turning off the main switch is not enough. Don't try to work on the CU live. Unless you have an isolator switch before the CU this would mean pulling the main fuse, which is illegal. You would need to arrange with your provider a date for them to do this, usually free. Then you would need to remove the rewirable fuses, fuse carriers and replace with MCBs. Only advantage really is convenience if a fuse trips. It may not cost much more to replace the CU with a modern split load type with RCD protection, but may be worth getting a qualified spark in as its notifiable under part P.

 

[jpdw]

First you would need to isolate the CU., turning off the main switch is not enough. Don't try to work on the CU live. Unless you have an isolator switch before the CU this would mean pulling the main fuse, which is illegal. You would need to arrange with your provider a date for them to do this, usually free. Then you would need to remove the rewirable fuses, fuse carriers and replace with MCBs.

Is it really the case that you have do all this in order to fit the kind of product that the OP refers? It appears (to me anyway) that the OP is referring to this sort of thing. The picture makes the unit LOOK like it has pins identical to the re-wirable's fuse carrier, suggesting it's a plug-in replacement and the product is called "plug in" too.

I too have one a wylex unit but figured I'd put the £50 quid I'd spend on these "towards" getting a spark to fit something with RCDs instead. Been here 9 months and no fuses have gone yet, so figured the inconvenience factor is not high -- if you're forever replacing fuse wire you probably have other problems and reasons to get a spark in !!!

 

[333rocky333]

The picture makes the unit LOOK like it has pins identical to the re-wirable's fuse carrier, suggesting it's a plug-in replacement and the product is called "plug in" too

THey do LOOK similar but
The bases on the mcb' s are thinner than the bases on the fuses
So they should be changed at the same time.

 

[RF Lighting]

First you would need to isolate the CU., turning off the main switch is not enough. Don't try to work on the CU live. Unless you have an isolator switch before the CU this would mean pulling the main fuse, which is illegal. You would need to arrange with your provider a date for them to do this, usually free.

Why?

You do not need to remove the CU cover to swap the back plate from fuse to MCB style.

The main switch IS adequate.

 

[JohnD]

RF is right

you don't take the cover off so the main switch is OK as it cuts power to the lower busbar.

You do not have to make any wiring changes or open the CU

you do have to change the plastic shields

only remove one at a time so you don't muddle up the positions of the ratings. I would always use an insulated screwdriver when screwing the new shields into place anyway and not poke my fingers inside (even though it will be dead). The busbar is covered except when you have removed one or more shields so only remove one at a time. Fix your circuit identifying labels before you start the swap.

if you want some MCBs to fit, make your email address visible in your Profile and you may find you get an offer off-forum.

Changing from fuses to MCBs is notifiable in England in Wales but I suspect that approx 0.00000% of such changes are notified.