CU 32->40a fuse upgrade

[JohnD]

probably not, but I found a pic showing the old style of MCBs.

 

[AndyPRK]

If you could take out 3 mcbs and the rear coloured part nearest the switch.
See if the one to the left of the switch has an extra cut out for the tab to go into.
If it does, could you see if the one to the right of the switch does too. Thanks

 

[nice-but-dim]

If you could take out 3 mcbs and the rear coloured part nearest the switch.
See if the one to the left of the switch has an extra cut out for the tab to go into.
If it does, could you see if the one to the right of the switch does too. Thanks

I will do but it will have to wait for the next power cut (we had a 6-hour beauty yesterday when the network infrastructure caught fire) or my next late night or early morning.

 

[AndyPRK]

I actually Meant JohnD, but yes you could do that as well

 

[nice-but-dim]

I actually Meant JohnD, but yes you could do that as well

JohnD has a photo.

 

[nice-but-dim]

It doesn't work like that.

The number and rating of MCBs connected does not cause power used to increase or decrease

I don't think I said otherwise, albeit my terminology may not be correct.

It doesn't work like that either.

An RCD does not trip on current usage.

OK.

he doesn't "passively confirm" that. He did not answer your question. he just said they are no longer offered. Your CU might have been designed to accept one or more 40A MCBs; this would be seen by the presence of (I think always only one) MCB-socket that was larger than the others and was capable of accepting the intentionally-larger (green?) 40A MCB used at the time. I don't see such a position in your pics.

At the time your CU was made, the MCBs were a different design, with two push-buttons. Yours has the (much) later switch type and perhaps when they were offered the B40 no longer had the protrusions. B40 were always very rare on Wylex Standard CUs.

I disagree. He would certainly have told me if my hunt for a B40 was pointless.

 

[ericmark]

I seem to remember a stronger clip to hold the MCB/Fuse over 30 amp. There seems to be some debate as to what is required the Best Practice guide says

Consumer units having rewirable fuses can continue to provide satisfactory service (cover removed for illustrative purposes)

 

[JohnD]

He would certainly have told me if my hunt for a B40 was pointless.

If you hunted through my loft you might find one.

But he would not have supplied it or accept any responsibility for it.

 

[flameport]

I seem to remember a stronger clip to hold the MCB/Fuse over 30 amp.

Correct - without that, overheating and failure is inevitable.

 

[AndyPRK]

This one appears to allow a high capacity fuse next to the switch as there is a cutout.

https://www.flameport.com/electric_museum/wylex_fuse_boxes/white_wylex_reverse_switch_dismantled.jpg

 

[securespark]

In days of old, when dinosaurs roamed the earth, technical for Wylex used to be in Wythenshawe, fairly local to me.

I used to fit a lot of Wylex and knew the technical guy who had worked there years. He told me that all Wylex boards are sub 100A unless marked.

And that the sub-100A boards are not designed for any circuit greater than 30 or 32A.

Some boards had a way to the right of the main switch which was designed for 35, 40 or 45A devices.

The fuse shields for these devices (orange and green) had a tab on the back, designed to prevent their fitting to an unsuitable board, which was often snapped off.

 

[AndyPRK]

Yes I put some links to eBay on the previous page which shows the tab.

I removed from my house one of the wooden boards with the separate high current way, however I wouldn’t consider it a 100A board.
I note the OP board is marked 100A. But being 12 way I wouldn’t expect less

 

[securespark]

Fair point. The ones with a separate way can be any amperage.

 

[AndyPRK]

Yeap. Mine only had a 30A in it.

 

[ericmark]

Correct - without that, overheating and failure is inevitable.

Thank you, I think these are your pictures, showing switch 60 amp rating,

showing standard contacts

With burning as not man enough.

And the uprated contact to right.
We all know what should be done including @nice-but-dim however some times there is a temptation to ignore what does not suit, there were two instant electric showers in this house and at least one did come from an old Wylex board, however it was on a 30 amp fuse carrier although no idea if it actually had 30 amp fuse wire in it.
This was my fuse box, it was trapped between the original garage ceiling and a new false ceiling, we had to cut a larger access hole to get to it and remove it, we at first did not even know it was there, there was a second consumer unit for the flat, only when I turned off the power and it did not go off did I notice the little hole in the plaster board top left, and then saw the fuse box through the hole, so you have it easy, at least you can see the old fuse board, I realised I may have been able to get a fuse out, but getting it back in was unlikely, so had to bite the bullet and get it changed.

You know it needs doing the same as I did, and you have to stop kidding yourself it will be OK.