Are you really sure a new CU is not going to fit? Let's have some good photos posted 
Moving Supply (DNO)
- Thread starter Greenie9657
- Start date
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What Westie said ...
If the distance (as the cable runs) is short, then you don't need anything but longer tails. The protection for the tails is deemed to be the downstream protection provided by the individual circuits in the CU.
ABove that, you can have any length you want - but you need to provide protection at the supply end. So that means a switch/fuse by the meter and then any length of cable to the CU.
The size/type/length of cable needs to be determined for the site. If it's a long run, then you may need a larger size to avoid volt drop problems for example. Otherwise it's down to the cable and the characteristics of the fuse - down to how much energy the fuse will pass under fault conditions, and what the cable can tolerate. Your sparky will be able to do these calculations for you.
As an aside, last time I had an EICR in the flat, the sparky came up with a non-compliance on the submain between the meter (in a cupboard in the communal area) and my CU. He had to check his books at home to confirm it, but the outcome was that with the size and length of cable it needed a size smaller fuse to be fully compliant.
A different electrician who'd done a check some years earlier hadn't flagged it.
If the distance (as the cable runs) is short, then you don't need anything but longer tails. The protection for the tails is deemed to be the downstream protection provided by the individual circuits in the CU.
ABove that, you can have any length you want - but you need to provide protection at the supply end. So that means a switch/fuse by the meter and then any length of cable to the CU.
The size/type/length of cable needs to be determined for the site. If it's a long run, then you may need a larger size to avoid volt drop problems for example. Otherwise it's down to the cable and the characteristics of the fuse - down to how much energy the fuse will pass under fault conditions, and what the cable can tolerate. Your sparky will be able to do these calculations for you.
As an aside, last time I had an EICR in the flat, the sparky came up with a non-compliance on the submain between the meter (in a cupboard in the communal area) and my CU. He had to check his books at home to confirm it, but the outcome was that with the size and length of cable it needed a size smaller fuse to be fully compliant.
A different electrician who'd done a check some years earlier hadn't flagged it.
Are you really sure a new CU is not going to fit? Let's have some good photos posted
There are photos somewhere from a previous thread. Ill have a look and repost them
Assuming it's this, there is plenty of space - especially if that tele-switch is removed/shifted.
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That looks a lot like my set up Lec. Haha.
The timing box (black) and the CU on the right have gone. I've done measurements and I can't seem to fit a new cu under there. Where are you thinking?
The timing box (black) and the CU on the right have gone. I've done measurements and I can't seem to fit a new cu under there. Where are you thinking?
Not with all that junk in there
What if the meter board (cutout and meter) were moved down and left ?
In principal that needn't require the incoming supply to be touched, just the cable to be flexed in an S bend. However, I'm sure people will pop up and point out that it would be "unwise" to do this yourself. It's not my area, but from the earth clip on the cable I'm guessing it's an oldish lead covered cable - and the potential to introduce a fault by disturbing a joint, and thus setting off a roman candle that sprays molten copper and lead in your face, cannot be discounted.
However, I'd have thought it shouldn't be an expensive move for your DNO to handle.
What if the meter board (cutout and meter) were moved down and left ?
In principal that needn't require the incoming supply to be touched, just the cable to be flexed in an S bend. However, I'm sure people will pop up and point out that it would be "unwise" to do this yourself. It's not my area, but from the earth clip on the cable I'm guessing it's an oldish lead covered cable - and the potential to introduce a fault by disturbing a joint, and thus setting off a roman candle that sprays molten copper and lead in your face, cannot be discounted.
However, I'd have thought it shouldn't be an expensive move for your DNO to handle.
I confess to being a bit confused. The OP says that the CU on the right and the tele-switch have now gone. Once the other CU has gone as well (replaced), I would have thought that there would be 'acres' of space available - certainly compared with some situations I've seen. I suppose I must be missing something!Not with all that junk in there
For the reasons you go on to describe, extremely unwise and potentially very dangerous (and 'not allowed') for anyone other than the DNO to attempt.
Kind Regards, John
Hi John
I think the photo is deceiving because it does look like there are aches of space but there really isn't. It's tight as anything and even if you could squeeze one in, the access for wiring would be horrible.
Simon, reading about molten metal in my face got my attention. Do you think the current set up is unsafe?
I think the photo is deceiving because it does look like there are aches of space but there really isn't. It's tight as anything and even if you could squeeze one in, the access for wiring would be horrible.
Simon, reading about molten metal in my face got my attention. Do you think the current set up is unsafe?
As long as it's not moved it will almost certainly be fine but attempting to move it yourself is a bad idea.
Moving any cable puts stress on both the cable and the terminations. This is especially true of old cables. As such moving a cable that is both old and live carries a risk that those stresses will cause the cable to fail and short out.
There is usually no fusing where a service cable meets the mains cable and as a result the next fuse back is sometimes insufficient to clear a fault resulting in the cable gradually destroying itself until someone upstream cuts off the power.
Moving any cable puts stress on both the cable and the terminations. This is especially true of old cables. As such moving a cable that is both old and live carries a risk that those stresses will cause the cable to fail and short out.
There is usually no fusing where a service cable meets the mains cable and as a result the next fuse back is sometimes insufficient to clear a fault resulting in the cable gradually destroying itself until someone upstream cuts off the power.
Am I right in saying that what we're talking about (having already got rid of the CU on the right and the tele-switch) is replacing the CU on the left? If so, if those two connector ('Henley') blocks were moved way down (so as to be fairly close to the meter), would there then not be quite a lot of space where the present CU (once removed) had been? As you say, maybe the photo is deceiving!
Kind Regards, John
Actually, on further thought, if you were going to end up with just a single CU, you wouldn't need those Henley blocks at all - which would make things even simpler.
Kind Regards, John
Unless you wanted to keep them as a means of disconnection without breaking the meter seals.
Hmmm. I'm not at all sure that we should be encouraging people to disconnect live meter tails (assuming that's what you mean)! Whatever, there's pleny of room 'down low' for re-siting those blocks (or, alternatively, an isolator) if one should so wish.
Kind Regards, John
Well that doesn't preclude pulling the fuse - which we also shouldn't encourage but in reality that's what lots of people do.
But it does mean there is a means of "dropping the tails" while leaving the meter seals intact.
How many people actually book an appointment with the DNO to pull the main fuse, and then wait for them to come back and put the fuse back ?
But it does mean there is a means of "dropping the tails" while leaving the meter seals intact.
How many people actually book an appointment with the DNO to pull the main fuse, and then wait for them to come back and put the fuse back ?
True, but if the fuse were going to be pulled (by whoever, wisely or not), then, whilst the meter seals could remain intact, the cutout ones wouldn't - so I don't really see the point!
One can but speculate about that (and the hazards are well described/discussed, particularly with older cutouts) - but, again, if the cutout fuse is going to be removed, the advantage (as you suggested) of retaining Henley blocks would go out of the window. In any event, as I said, there's plenty of room for Henley's (or an isolator), if the OP's electrician wants to keep them.
Greenie9657: is there any chance of us seeing a photo of what it looks like now that one of the CUs and the teleswitch have been removed?
Kind Regards, John
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