What size is this supply?

[John-SJW]

A relative in West Cheshire sent me this pic. He is contemplating having an EV charger and other electrical appliances fitted. He asked me if he has a 60A or 100A supply. From this pic, it looks like a 100A supply with 60A fuse fitted for some reason. He wants it to be 100A. Any ideas?

 

[DPG]

A relative in West Cheshire sent me this pic. He is contemplating having an EV charger and other electrical appliances fitted. He asked me if he has a 60A or 100A supply. From this pic, it looks like a 100A supply with 60A fuse fitted for some reason. He wants it to be 100A. Any ideas?

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We can only go on the same info as you, and so I would agree - a 100A carrier with 60A fuse.

Get him to contact supplier to see if they can upgrade it

 

[JBW175]

It’ll be a 60 Amp supply fuse inside the service head.

They’ll need to speak to the DNO if they want the supply uprating to 100 Amp.

 

[7029 dave]

I would say 60A fuse in that cut out, they would not have labelled it otherwise.
Best to contact the DNO to have a look, and possible upgrade.

 

[littlespark]

What a pity we’re (generally) not allowed to pull the fuse, open up the carrier and have a look.

I know electricians are supermen among tradespeople, but x ray vision is beyond even me.

 

[JBW175]

What a pity we’re (generally) not allowed to pull the fuse, open up the carrier and have a look.

I know electricians are supermen among tradespeople, but x ray vision is beyond even me.

Sometimes that pesky little fuse fairy helps us out…

 

[John-SJW]

I know DNOs in some areas were putting in 60A main fuses in 100A supplies. I assume to discourage excessive use as their system overall cannot cope. Like some here, I assume this is a 100A supply with a 60A fuse. So a 100A fuse would not harm anything.

If the DNO a number of years back did downgrade the fuse, then it would be matter of slotting a 100A fuse back in. Even if the DNO does not know. How naughty.

If the house was orginally 100A, then they downgraded it to 60A, then they have to upgrade at their expense?

 

[John-SJW]

Sometimes that pesky little fuse fairy helps us out…

I believe his name is Pablo.

 

[John-SJW]

We can only go on the same info as you, and so I would agree - a 100A carrier with 60A fuse.

I agree. The 25mm tails from the service head to the meter is a give away. If it was 60A from the start, it would be 16mm.

 

[timhoward]

I’m sure you/your relative are aware already, but if EV is the motivation then there are some pretty clever chargers these days that monitor the demand and only charge when the cooker/shower are not in use.
So all is not lost with a 60 amp supply. I still have 60A at my house.

 

[nicebutdim]

I know DNOs in some areas were putting in 60A main fuses in 100A supplies. I assume to discourage excessive use as their system overall cannot cope. Like some here, I assume this is a 100A supply with a 60A fuse. So a 100A fuse would not harm anything.

If the DNO a number of years back did downgrade the fuse, then it would be matter of slotting a 100A fuse back in. Even if the DNO does not know. How naughty.

If the house was orginally 100A, then they downgraded it to 60A, then they have to upgrade at their expense?

Cut out might be rated to 100A, but if a 60A fuse is fitted it's a 60A supply.

In other news, I'd suggest not going down the route you seem to be headed - especially after posting images that identify the property in question to any DNO employees who might stumble upon this thread.

 

[timhoward]

I’m never good at identifying earthing conductor sizes from photos - but they all look similar making me wonder if they are all 10mm sq mm?

 

[DPG]

I know DNOs in some areas were putting in 60A main fuses in 100A supplies. I assume to discourage excessive use as their system overall cannot cope. Like some here, I assume this is a 100A supply with a 60A fuse. So a 100A fuse would not harm anything.

If the DNO a number of years back did downgrade the fuse, then it would be matter of slotting a 100A fuse back in. Even if the DNO does not know. How naughty.

If the house was orginally 100A, then they downgraded it to 60A, then they have to upgrade at their expense?

No, it wasn't originally a 100A supply. It's just the maximum rating of the cut out is 100A. Just like the max rating of an isolator for example.

 

[7029 dave]

The supply cable might not be rated at 100AMPS, DNO need to survey.
They are the only one's who can up grade or de grade the main fuse, not even the energy company can do that.

 

[John-SJW]

No, it wasn't originally a 100A supply. It's just the maximum rating of the cut out is 100A. Just like the max rating of an isolator for example.

Every 60A supply I have seen had 16mm cable from the fuse to meter. This may have been an exception though.

 

[John-SJW]

He said he thinks that 60A label was put on when he went over to a smart meter. If you look at the seal it looks newish, which may indicate the fuse was downrate, being initially a 100A fuse.

 

[DPG]

He said he thinks that 60A label was put on when he went over to a smart meter. If you look at the seal it looks newish, which may indicate the fuse was downrate, being initially a 100A fuse.

They may well have put a label on to identify the fuse. They probably didn't change the fuse though.

 

[Lister1987]

Thought it would be a 63A, not 60A? 63 80 100

 

[Julie.]

Thought it would be a 63A, not 60A? 63 80 100

Bs1361 and bs88 service fuses are 30, 40, 50, 60, 70, 80, 90 and 100A

60, 80 and 100A being the common ones.


Others such as j type or A3, A4 etc are indeed 63A

 

[littlespark]

Am I right in saying that some meters are only rated to 80A, so can’t have a 100A fuse.
Can’t tell from your photo.

 

[Julie.]

Am I right in saying that some meters are only rated to 80A, so can’t have a 100A fuse.
Can’t tell from your photo.

Yes, although I think most if not all "smart" ones are 100A
My home "traditional" meter is 80A.

I looked at that and it looks like it is from the E470 series, which is 100A, but it isn't clear enough to see properly.

Ultimately the DNO is the only one to indicate what the max rating is, the size of the fuse carrier, cable, meter etc only gives a possible upper limit.

The capacity of the network, could also be a limit.

DNOs and suppliers/meter fitters standardise on ratings of kit, they stock only 100A carriers (to reduce stock levels), many now only use 25mm^2 so the meter fitters don't have to learn to size cables.

That intake has a limit of 60A due to the fuse, changing the fuse doesn't necessarily mean the capacity can be increased, it may be, but it may be it means something is unprotected against overload.

 

[DPG]

Let us know what they say when your friend contacts them.

 

[John-SJW]

They may well have put a label on to identify the fuse. They probably didn't change the fuse though.

I think the newish looking seal is the give away. It would have been put there when the meter was changed. Nevertheless we do not know, until the fuse is looked at, and the incoming cable assessed of being capable of supplying 100A.

 

[DPG]

I think the newish looking seal is the give away. It would have been put there when the meter was changed. Nevertheless we do not know, until the fuse is looked at, and the incoming cable assessed of being capable of supplying 100A.

Absolutely. No way of knowing. Has your friend contacted the supplier yet?

 

[Julie.]

I think the newish looking seal is the give away. It would have been put there when the meter was changed. Nevertheless we do not know, until the fuse is looked at, and the incoming cable assessed of being capable of supplying 100A.

It doesn't matter if the incoming cable is capable of 100A, it still doesn't mean that supply has a capacity of 100A.

DNOs apply diversity just as electricians do, the capacity of the distribution transformer determines how many supplies may be connected at 60A, upping some customers to 100A may well mean a larger transformer is required.

One cannot assume that because a certain size cable, fuse carrier, meter etc has been fitted that there is capacity.

I doubt the fuse has been changed, the meter fitter is likely to have removed the fuse, fitted meter, refited the fuse, applied new seals, and applied a label showing the fuse size.