UK 100 Amps or 60 Amps

Thanks everyone for the past inputs - it's been very helpful.
Updates:
I finally got through to SSEN and after much waiting got through to a 'connections' dept. They couldn't find any relevant data on my house, but asked for an email with detailed request, plus photos of meter / fuse and outside shots. The guy on the phone said he had no access to records such as fuse fitted or whether we were on a loop supply from next door.
Had chat with next door - we are both convinced there are two separate supplies from the gable end point. A new run would be required along the front of both houses as the back is now covered by various extensions making running here impractical.
So photos taken and Thursday got round to putting it all in email.
Blow me - Friday morning had a reply that they will put together a quote - and I might have to pay towards the quote. ??
Staggering - this afternoon I got a quote - £65 to change the main fuse to 100 amps
No mention that the existing cabling is adequate - but presume it is ?

Firstly, snap their hand off!
With caveat that I'm never great at telling cable sizes from photos, so my impression is:
From the DNO's point of view the tail sizes (25 sq mm) are adequate for 100A as far as the isolator switch (and a bit further to where they split and change to old colours).
It's virtually certain that the loading on each board is within the capacity of the red/black 16 sq mm tails, and I think you said the garage supply will be fused at 60A so the future use with EV should be ok.

Two things bothering me a bit:
Looks like no grommet/tails gland on the Switched Fuse (presumably for garage on right) where tails enter.
As it's PME I'm particularly interested (and having difficulty) deciding what size those earthing conductors are....are they all 16mm? Looking more like 10mm to me.

timhoward said:

Firstly, snap their hand off!
With caveat that I'm never great at telling cable sizes from photos, so my impression is:
From the DNO's point of view the tail sizes (25 sq mm) are adequate for 100A as far as the isolator switch (and a bit further to where they split and change to old colours).
It's virtually certain that the loading on each board is within the capacity of the red/black 16 sq mm tails, and I think you said the garage supply will be fused at 60A so the future use with EV should be ok.

Two things bothering me a bit:
Looks like no grommet/tails gland on the Switched Fuse (presumably for garage on right) where tails enter.
As it's PME I'm particularly interested (and having difficulty) deciding what size those earthing conductors are....are they all 16mm? Looking more like 10mm to me.

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Hi Tim
Thanks for your reply and keen observations.
You are correct on all counts.
As the original meter economy 7 clock was faulty my electrician (Dan) suggested getting the meter changed and ask for an isolator. It was £60 charge to me for the isolator, but Dan said it will make life much easier on bringing the rest up to spec. The meter guy also fitted new blocks to take 25mm which helps further.
Yes - the earths are undersize - so they are now due to be changed to 16mm throughout, plus upping the tails elsewhere as appropriate.
Yes - I'm frankly astounded that DNO can just change the fuse, I was expecting a couple of grand quote for upgrading their supply cable from next door's gable. I presume they have historic record of their cables. FYI the supply in is only 13.5 mm OD (just measured with vernier). Seems small for 100A ?
We are planning a new 16mm SWA to the outbuilding, plus retain the existing 10mm SWA and use that only for shed and garage (and EV point one day). So we'll have 60A capable for outbuilding, plus 40A for shed / garage.
We are assuming 40 amps for shed garage should cover a typical EV charge point.
Both SWA's will have new boxes with I think Dan said RCBOs ?
Currently I have one of those 'self fit' garden supplies that plugs in a house socket with an RCD and flex to a box outside. It used to be fine but the pond pumps throw out half of the house consumer unit when faulty (already replaced 1 pump)
So all that will get reorganized and garden stuff come off the shed supply.
Need new consumer unit in outbuilding plus new smaller units for shed and garage.
Plus change the house consumer unit for metal as it's near the stairs.
So a lot to do !

BUT - with the recent hike in electricity prices I will be looking carefully at our energy - we are using too much generally. So insulation projects plus things like change hob from ceramic to induction. Hoping long term that 100A fuse will have little to do most of the time !

Dan will be busy - hoping insulation tests on the existing house wiring goes ok.

timhoward said:

I'm not an expert in EV chargers, but I'm given to understand that if you have a looped supply, and a 60 amp supply, then unfortunately both of these are hurdles that will need overcoming.
I've heard of instances where DNO (SSE) will unloop without charging. Others know more about this area of electrickery than me.

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Some dnos will allow you to fit an ev charger on a 60a loop supply subject to load balancing with use of wired ct clamps or harvis such as the zappi stuff.
Most will get a bit jittery about it. In my experience ssen are a nightmare to deal with and try to charge for everything. On a positive they do allow fuses to be pulled.
Wpd are brilliant will unloop and upgrade to 80/100 amps at same time free of charge.
If customer doesnt want the groundworks they usually say fit charger subject to complying with g100 and ena guidance which brings us back to ct clamps either from the chsrger or third party.unit such as the matt:e..
A 40amp supply to an outbuilding would work for a charger subject to volt drop etc as the Myenergi zappi cam work off submains and load balance this and the house.
Just need yo understand the ct settings and groups etc within the menus. Its demonstrated in the Myenergi wiki and tech support.
I did.one recently. The garage/office had a 40 amp feed, by setting up the kit correctly power lights and an electric shower in there are all working.alongside a charger due to load balancing.
Its all in the planning

AndyBuzz said:

Yes - I'm frankly astounded that DNO can just change the fuse, I was expecting a couple of grand quote for upgrading their supply cable from next door's gable. I presume they have historic record of their cables. FYI the supply in is only 13.5 mm OD (just measured with vernier). Seems small for 100A ?

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It's not uncommon to be scratching our heads about the lengths we are obliged to go to running big enough cables within the installation when the incoming supply is a fairly small cable.
But the DNO has different rules, the BS7671 rules we sparks work to start at the end of the meter tails or isolator and are a lot more conservative.
I'd accept the quote and see what the person tasked with doing it says they turn up.

buzzlightyear said:

I'm worried your electrician had not thought about that .
rephrase it IDIOT .lol

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Buzz is giving English lessons!!??!! ??

Gavin John Hyde said:

Some dnos will allow you to fit an ev charger on a 60a loop supply subject to load balancing with use of wired ct clamps or harvis such as the zappi stuff.
Most will get a bit jittery about it. In my experience ssen are a nightmare to deal with and try to charge for everything. On a positive they do allow fuses to be pulled.
Wpd are brilliant will unloop and upgrade to 80/100 amps at same time free of charge.
If customer doesnt want the groundworks they usually say fit charger subject to complying with g100 and ena guidance which brings us back to ct clamps either from the chsrger or third party.unit such as the matt:e..
A 40amp supply to an outbuilding would work for a charger subject to volt drop etc as the Myenergi zappi cam work off submains and load balance this and the house.
Just need yo understand the ct settings and groups etc within the menus. Its demonstrated in the Myenergi wiki and tech support.
I did.one recently. The garage/office had a 40 amp feed, by setting up the kit correctly power lights and an electric shower in there are all working.alongside a charger due to load balancing.
Its all in the planning

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Many thanks for reply.
I'm convinced now we are not on a loop supply. Looks like two feeds come off the gable, so one for nearest half (No1) and one for us (longer run to No2).
Next door at No1 there is only one supply cable terminating at their main fuse.
All good stuff there Gavin for me to learn ref the EV charging - appreciated !

AndyBuzz said:

I'm convinced now we are not on a loop supply.

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I meant to say, I could see no evidence of a looped supply in the photos.
Do report back as this job unfolds, it's an interesting one!

timhoward said:

It's not uncommon to be scratching our heads about the lengths we are obliged to go to running big enough cables within the installation when the incoming supply is a fairly small cable.
But the DNO has different rules, the BS7671 rules we sparks work to start at the end of the meter tails or isolator and are a lot more conservative.
I'd accept the quote and see what the person tasked with doing it says they turn up.

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Yep - I'll accept and post an update. Though they have said up to 8 weeks !!

timhoward said:

I meant to say, I could see no evidence of a looped supply in the photos.
Do report back as this job unfolds, it's an interesting one!

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Will do Tim. Many thanks