Do I change my cables?

[Flinders]

Hi, It has been noted during installation/conversion to an Electric Smart Meter that my switch gear is on 16mm cable and the new meter supply is now on 25mm.
Do I have to change mine to 25mm or is it ok to continue as is? Thanks for any advice. John

 

[conny]

When you say, 'switchgear', do you mean the leads from the meter to your consumer unit?

 

[Murdochcat]

All depends on the size of the main fuse AND I would not recommend this to be a DIY job..........

 

[opps]

I am not an electrician...

If they are not upgrading the rating of the main fuse, I can't see why the tails from the smart meter to the consumer unit need to be upgraded, but I suspect that they will insist that they are upgraded.

The following may help

Can OVO upgrade my meter tails and how much would this work cost? | The OVO Forum

How much do OVO change to have meter tails upgraded from 16mm2 to 25mm2?

forum.ovoenergy.com

 

[Murdochcat]

There are plenty of so called "electricians" stating they have to be upgraded to 25 mm despite the fact that the majority of main fuses being 60A or 80A - which is 100% wrong

Most new installs are built with 25 mm tails irrespective of what the main fuse is

Personally I would not worry about it unless you have an EV charger, a hot tub, electrical boiler, etc etc

 

[EFLImpudence]

Yes, if everything was alright before, it will be alright now.

 

[Flinders]

Firstly rest assured I have no intention to make this a diy job. I was left a Safety Advisory Notice form which pointed out in the Advisory section that firstly that "the existing main switches may require upgrading" and secondly "Uneven cable sizes". Then under Additional Notes he wrote Multiple Switchgear, Old type 16mm on customer side, 25mm on our side. Electrician to inspect + upgrade. There is no demand to do anything and no date by which anything should be done so I was left with the question in my mind is this a case of it would be nice to have or a case of MUST do. Hence my question as I want to know with what urgency I have to move. To answer your questions There is a odd shaped black box where the mains cables enter the house that has two metal wired clips on and two 25mm cables that go to the meter. Imprinted on this black box is 100A. From the meter 25mm cables connect to switched Fuse boxes each containing 60A fuses that then carry the 16mm cables to the domestic fuse boxes.
Thanks

 

[EFLImpudence]

Firstly rest assured I have no intention to make this a diy job. I was left a Safety Advisory Notice form which pointed out in the Advisory section that firstly that "the existing main switches may require upgrading"

May?

and secondly "Uneven cable sizes".

He made them uneven.

Then under Additional Notes he wrote Multiple Switchgear, Old type 16mm on customer side, 25mm on our side.

I very much doubt that their side (i.e. coming in from the street) has 25mm² cable.

Electrician to inspect + upgrade. There is no demand to do anything and no date by which anything should be done so I was left with the question in my mind is this a case of it would be nice to have or a case of MUST do. Hence my question as I want to know with what urgency I have to move. To answer your questions There is a odd shaped black box where the mains cables enter the house that has two metal wired clips on and two 25mm cables that go to the meter. Imprinted on this black box is 100A.

That is just the maximum rating. It is no indication of the actual fuse rating.

From the meter 25mm cables connect to switched Fuse boxes each containing 60A fuses that then carry the 16mm cables to the domestic fuse boxes.
Thanks

If that is the case then all is well.

 

[ericmark]

Clipped direct 16 mm² is rated at 87 amp See here on the chart on a continuous basis even with a 100 amp supply it will never exceed that for long enough to be a problem, my home like many older homes is on a 60 amp fuse as the old Wylex fuse boxes the main isolator was only rated at 60 amp so for the supplier to fit a larger one he would be in breach of health and safety regulations, with a 60 amp fuse your well within the limits.

 

[Flinders]

Thank you for the feedback. Yes, I opened each of the fused switch boxes and visually confirmed they are 60A. Of course I couldn't confirm the first one in the black box as to do so would have meant I had to break their seals.
It did seem odd that no update was asked for or do it by.
It's worked exactly like it is perfectly for the last 21 years (my tenure) and there was no sign of the previous owners having carried out any recent works either.

 

[EFLImpudence]

Clipped direct 16 mm² is rated at 87 amp See here on the chart on a continuous basis even with a 100 amp supply it will never exceed that for long enough to be a problem,

The Distribution Network Operators have different rules and use 16mm² for 100A supplies.

my home like many older homes is on a 60 amp fuse as the old Wylex fuse boxes the main isolator was only rated at 60 amp so for the supplier to fit a larger one he would be in breach of health and safety regulations,

If you mean a larger isolator - Why?

It would make no difference; much the same as using 25mm² cable where 16mm² is adequate.

If you mean a larger fuse it would be wrong but no one has suggested either.

with a 60 amp fuse your well within the limits.

Yes.

 

[Flinders]

One final question if I may,
Can I just ignore this Safety Advisory Notice or do I still have to get an electrician in to confirm what you have said and do I need him/her to confirm in writing?

 

[EFLImpudence]

Can I just ignore this Safety Advisory Notice or do I still have to get an electrician in to confirm what you have said and do I need him/her to confirm in writing?

From the information we have I would say yes, you can ignore it.

Perhaps you could contact the supplier (company that fitted the meter) and ask them to explain.