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Discussion Starter · #1 ·
I'm planning works for a new consumer unit, to support an ASHP and in future an EV charger (don't have an EV at present but next car will be an EV so might as well do the internal work now). I don't know what the main fuse is, but the tails are all 16mm2 with an elderly cutout fuse (70s bakelite? Marked BICC). I'd guess maybe 60A? The incomer is 16mm2 as well, although that should be OK if it's copper (probably mid-60s, it's TN-S).

Since I'm doing the CU anyway, it would be handy to get everything (beyond the service head) replaced - smart meter, 25mm2 tails, upgrade to 100A fuse, add an isolator. That would make the CU replacement easier as well. Doing it all in one go would also make the best use of limited space on the meter board.

My current electricity supplier is Symbio who are cheap as chips but useless at customer service. So I'd be thinking of changing supplier for the purposes of getting the new supplier to do the works.

So the question is: who are a good electricity supplier for doing work like this, who are currently installing smart meters on a non-glacial timescale?
 

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Discussion Starter · #5 ·
That's interesting. How far in the future did Octopus book your install date? Any ideas what they charge for work on tails and isolators?

(by the way, I'm aware replacing the main fuse is the DNO's job - but DNO won't upgrade until the tails are up to scratch. I will however call them to see if they have a record of what cutout fuse we have)
 

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I was in discussion with Octopus about my existing smart meter, which didn't seem to be commissioned properly a year ago.

Once they decided a new smart meter was the right answer ... the appointment was made for a week ahead. No delays there...
 

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That's interesting. How far in the future did Octopus book your install date? Any ideas what they charge for work on tails and isolators?

(by the way, I'm aware replacing the main fuse is the DNO's job - but DNO won't upgrade until the tails are up to scratch. I will however call them to see if they have a record of what cutout fuse we have)
They sent me a text message saying I could book.an install and offered dates within a month onwards.

If they actually end up installing it is another question, it's three phase and three phase meters have only just become available. They are aware of the situation though. As for the tails and isolator these were done on a previous none smart meter install a few years ago (meter was faulty). They did this without asking at no cost it's probably down to the installer ?
 

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I don't know what the main fuse is, but the tails are all 16mm2 with an elderly cutout fuse (70s bakelite? Marked BICC). I'd guess maybe 60A? The incomer is 16mm2 as well, although that should be OK if it's copper (probably mid-60s, it's TN-S).
As above, the supplier won't touch the incomer or main fuse as it's the property of the DNO. I doubt very much that the incomer is anywhere near as small as 16mm², as for as long as I can remember electricity boards, and then DNOs, have used 35mm² Al/Cu concentric, either single for TN-C-S or split for TN-S. Even the old lead covered cable was bigger than 16mm² and they stopped using that some time back in the 1950s or 60s, at the time when they switched from using ceramic or pitch-filled cast iron incoming terminations.

35mm² concentric does look very thin, but that's just because of its design and lack of any armour. The rules regarding cable protection are different for DNOs and they are permitted to use non-armoured cable with no protection in locations that are not permitted under BS7671 as they work to the rules that are in ESQCR instead.

The DNO should have no problem with uprating the fuse if that is needed, but may need to change the head as well if it is one of the very old ones that had a habit of going brittle. Worst offenders, other than the very old iron and porcelain ones, are the jet black ones made of something like Bakelite that develops cracks and goes brittle with age, such that just pulling the fuseholder out may cause it to crack or break and leave live parts exposed. DNOs will need to turn off the power to your local area at the sub-station to replace the head, as they no-longer do live working to the degree that they used to in the past.
 

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If it helps, I'm going through the same process. Avro energy are booked in to come and change the meter tails and put an isolator switch in while they're here. Might be doing some building work next year so hopefully an isolator switch will help with any faff. I had to e-mail them as they have closed their phone lines due covid - took a week to get back to me, but then booked an appointment in straight away, very easy. Appointment was about 4 weeks future.

Once that is done, DNO (SSEN) are coming to upgrade my fuse from 60A to 100A. Cost £70. Have attached a pic - I couldn't see a label, but 60A is written in TINY lettering here, so maybe double check again just in case.

Then pod point should be able to come round and get the EV charger in easily. Electrical wiring Gas Cable Audio equipment Electricity
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If it helps, I'm going through the same process. Avro energy are booked in to come and change the meter tails and put an isolator switch in while they're here. Might be doing some building work next year so hopefully an isolator switch will help with any faff. I had to e-mail them as they have closed their phone lines due covid - took a week to get back to me, but then booked an appointment in straight away, very easy. Appointment was about 4 weeks future.

Once that is done, DNO (SSEN) are coming to upgrade my fuse from 60A to 100A. Cost £70. Have attached a pic - I couldn't see a label, but 60A is written in TINY lettering here, so maybe double check again just in case.

Then pod point should be able to come round and get the EV charger in easily. View attachment 144697 View attachment 144698
60A moulded into the thing suggests that's the maximum the fuseholder can carry. It's possible the DNO will fit a new fuseholder.
 

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Mate of mine also doing the same - his DNO came and swapped the fuse last week and he got this, so wondering if I might get the same. Who knows - will report back :)


View attachment 144699

Worth noting that the "100A" on the fuse carrier is not the fuse rating, it is the rating of the carrier. It's a PITA, but the DNOs rarely, if ever, put the actual fuse rating on these things.

This is a photo of mine, where I added my own label on the fuse carrier when I pulled the fuse to check what it was some time ago, and it would be really helpful if DNOs or meter monkeys did this routinely every time they have a reason to pull the fuse. It's a pet hate of mine not knowing what the fuse rating is, as very often it's either not marked or incorrectly given in an old EIC or EICR.

144701
 

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As above, the supplier won't touch the incomer or main fuse as it's the property of the DNO. I doubt very much that the incomer is anywhere near as small as 16mm², as for as long as I can remember electricity boards, and then DNOs, have used 35mm² Al/Cu concentric, either single for TN-C-S or split for TN-S. Even the old lead covered cable was bigger than 16mm² and they stopped using that some time back in the 1950s or 60s, at the time when they switched from using ceramic or pitch-filled cast iron incoming terminations.

35mm² concentric does look very thin, but that's just because of its design and lack of any armour. The rules regarding cable protection are different for DNOs and they are permitted to use non-armoured cable with no protection in locations that are not permitted under BS7671 as they work to the rules that are in ESQCR instead.

The DNO should have no problem with uprating the fuse if that is needed, but may need to change the head as well if it is one of the very old ones that had a habit of going brittle. Worst offenders, other than the very old iron and porcelain ones, are the jet black ones made of something like Bakelite that develops cracks and goes brittle with age, such that just pulling the fuseholder out may cause it to crack or break and leave live parts exposed. DNOs will need to turn off the power to your local area at the sub-station to replace the head, as they no-longer do live working to the degree that they used to in the past.
SSE still work live, depending on circumstances.
 

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SSE still work live, depending on circumstances.
And the age of the person doing the job!

I nearly made a young lad have heart failure when (for a very good reason) I opted to put on gloves and visor and work live on an installation. He went into overdrive about how this was forbidden and that it was mandatory to lock off the supply and prove dead before work. I pointed out that I'd been trained to work on live circuits, understood the risks and had enough common sense to be able balance the risk against the inconvenience caused by isolating the whole supply. Poor little sod still didn't get it at all and in the end I had to just remind him that he was an electrician and that meant working with electricity, albeit as safely as practicable for the circumstances. Goodness only knows what he'd have made of live working on a big main . . .
 

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And the age of the person doing the job!

I nearly made a young lad have heart failure when (for a very good reason) I opted to put on gloves and visor and work live on an installation. He went into overdrive about how this was forbidden and that it was mandatory to lock off the supply and prove dead before work. I pointed out that I'd been trained to work on live circuits, understood the risks and had enough common sense to be able balance the risk against the inconvenience caused by isolating the whole supply. Poor little sod still didn't get it at all and in the end I had to just remind him that he was an electrician and that meant working with electricity, albeit as safely as practicable for the circumstances. Goodness only knows what he'd have made of live working on a big main . . .
Definitely right there. Did you ask what the VDE tools were for?
 

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Discussion Starter · #17 ·
If it helps, I'm going through the same process. Avro energy are booked in to come and change the meter tails and put an isolator switch in while they're here. Might be doing some building work next year so hopefully an isolator switch will help with any faff. I had to e-mail them as they have closed their phone lines due covid - took a week to get back to me, but then booked an appointment in straight away, very easy. Appointment was about 4 weeks future.
Was the £70 the whole thing, or just the DNO visiting to change the fuse? How much was the isolator and tails? Was that at the same time as a smart meter fit?

I emailed Octopus on Sunday night. No reply yet...
 

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Was the £70 the whole thing, or just the DNO visiting to change the fuse? How much was the isolator and tails? Was that at the same time as a smart meter fit?

I emailed Octopus on Sunday night. No reply yet...
£70 was the DNO fuse.

Avro list the cost of isolator switch install as being £60 (from memory) and hoping the tails are going to be free (actually that reminds me I should really check!)
 

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Discussion Starter · #19 ·
As above, the supplier won't touch the incomer or main fuse as it's the property of the DNO. I doubt very much that the incomer is anywhere near as small as 16mm², as for as long as I can remember electricity boards, and then DNOs, have used 35mm² Al/Cu concentric, either single for TN-C-S or split for TN-S. Even the old lead covered cable was bigger than 16mm² and they stopped using that some time back in the 1950s or 60s, at the time when they switched from using ceramic or pitch-filled cast iron incoming terminations.
I measure the circumference of the tails by wrapping a bit of paper around them and marking with a pen:

Bitumen-wrapped incomer, where it splits into service head: 34mm
Service head to meter: 34mm
Meter to Henley Block: 34mm
Henley Block to CU: 32mm

Dividing by pi means they're all about 10mm diameter, give or take measurement error. I think that means 16mm2 copper underneath the insulation?

I can't actually tell if the sheath is lead or not, it disappears behind a panel into the floor. It was probably installed in the mid 60s. I've added some pictures of what I have.

144764
144765
 

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The snag is that there is a massive difference in the insulation thickness between double insulated tails and the concentric incomer cable. Take a look at the photo I posted above of a 7 year old installation, in post #12 above. The thin black incomer at the lower left is 35mm, the thick grey tails at the right are 25mm.
 
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