Main Incoming Supply

[besenzig]

Main Incoming Supply

• besenzig
• 13 Sep 2010
• 2

Hi

I am trying to understand the arrangemnt in my main incoming supply. Could some please explain the following:

1. Why is the main service 60A fuse is not sealed.
2. Why do I have a 32A sealand fuse to the right of the main service fuse, what is this for.
3. What is the black box to the right of the meter.
4. I am used to seeing just a main L & N supply going into a meter and from there tails going into the CU, but do not understand this one in the picture.
5. Is it possible to get the DNO to rip this out and just install a standard meter with a DP switch disconector in the tails.

Thank you

 

[securespark]

That's a white meter.It has the ability to record low tariff usage as well as standard.

The low tariff is controlled by the black unit on the right, a teleswitch, which will switch you over to the low rate overnight.

If you use a lot of electricity overnight, this set-up makes sense. Lots of folk put the dishwasher / washing machine etc on during this time to take advantage of the low rate.

White meters are also common in properties which have storage heaters. These are energised overnight on the low rate and let out the heat during the day.

 

[besenzig]

The property where this arrangement is set up has the CU on the internal wall under the bay window,directly behind the white meter, not very practical. I would like to get the supply run back to under the stairs some 8 meters away whilst still leaving the meter outside.

Can anyone tell me whats involved? Thank you

 

[flameport]

Suitable cable from the meter position to the new CU will be installed, with a switchfuse at the meter end. Most likely split concentric or SWA cable.
All of the circuit cables connected to the CU will need to be extended to the new position.
All of the circuits will need to be inspected and tested, and any repairs completed before the circuits are energised. Unless the existing CU is very new, it is likely that the CU would be replaced at the same time.

Expect to pay at least £500 for this, could easily be a lot more.
This is not DIY work either, and I really can't see how hiding a CU under the stairs would be more convenient for anyone?

 

[Chri5]

The property where this arrangement is set up has the CU on the internal wall under the bay window,directly behind the white meter, not very practical. I would like to get the supply run back to under the stairs some 8 meters away whilst still leaving the meter outside.

Why is it impratical ?

Or do you simply find the location offends your eyes? What is the existing set up, new CU or older type, how many mcb / fuses on it, do these meet your current and future needs ?

Sorry about the question marks, but you can get semi or full recessed CU's. Flats get away with smaller CU's that are easier to 'hide'.

Boxing in is fine, bay window seat and a decent access panel ?

For a switch fuse, a 100amp cable, new CU, cert, 8m cable run and 8 x final circuits being moved (or pulled back or extended) plus any remedials on existing circuits updating to rcds and then full test.
I'd suggest it would be double the last figure quoted

 

[Lectrician]

That's a white meter.It has the ability to record low tariff usage as well as standard.

The low tariff is controlled by the black unit on the right, a teleswitch, which will switch you over to the low rate overnight.

If you use a lot of electricity overnight, this set-up makes sense. Lots of folk put the dishwasher / washing machine etc on during this time to take advantage of the low rate.

White meters are also common in properties which have storage heaters. These are energised overnight on the low rate and let out the heat during the day.

It is NOT a white meter (well, ok, its coloured white).

It is a DUAL RATE METER.

White meters typically refer to the old white tarrifs where you had one rate for standard electric 24/7, and a switched supply during the night for use only with storage heating which would have it's usage recorded on a 'white meter'. Only the storage heaters would use cheap lecky.

A dual rate meter is used with the tele-switch to provide cheap rate electric to the entire installation.

 

[besenzig]

Flameport thanks for your input.

Essentailly we need to create a sub main in 25mm SWA with a switch fuse at the meter end, say one of these

http://www.tlc-direct.co.uk/Products/WY108M.html

but how would we introduce some form of descrimination if the service fuse is rated at 60A, the same as the Wylex switch fuse....? Would 2 x 60A be acceptable? don't really want to drop the Wylex down to 45A.

Any thoughts..

 

[Chri5]

So if the swa got hacked by a spade and you had a 60 amp service fuse and a 60 amp switched fuse which do you think would pop 1st ?

Are you intending on doing this work, if so please don't.

 

[besenzig]

chri5

Thanks for your comments.

1.There is no way a spade going through the swa, I'd like to see you have a go.

2. The SWA will be under the living room floor with a void of 3 feet and then up under the stairs where it will be visible.

3. Clearly I will not be doing it myself but going through the process of understanding what needs to be done. If the main service fuse could be uprated to say 80A (only the DNO would know this) then a 60A on the Switch fuse at the meter end of the cable would work.

Do you have a solution? I would be very interested to see how you would resolve the issue.

Thanks

 

[Chri5]

What I'm suggesting is that the DNO 3m rule between CU and head is bypassed by using a switched fuse (as you know).

The reason for the switched fuse is to provide protection for the tails / swa / conc cable since the rule of thumb is that they are yours not the DNO's.

If anything happens to the cable or the system has a overload (would need to be about 90 amps) a fuse would go.

Guess which one

Discrimination doesn't apply between a standard CU with a RCD and the supplier fuse all the time.

Plenty of suppliers fuses at 60 amp and rcds at 80 amp.

So unless my logic is flawed, I see no reason why you need discrimination because the switched fuse that you fit will fail first,

 

[holmslaw]

..

 

[besenzig]

Chri5

Yes the switch fuse is to overcome the 3m rule as you say.

Are you then agreeing that a 60A service fuse and a 60A on the switch fuse on the tails would be acceptable? protecting the 25mm SWA as discrimination is not required between the CU and the service fuse.

 

[besenzig]

holmslaw...

'A switched fuse' is dyslexia (I think thats how you spell it) taking over my keyboard...

 

[Taylortwocities]

Shall we play "spot the pedant"

 

[flameport]

The issue of discrimination is irrelevent in this instance, as there is no guaranteed discrimination between 60A/80A/100A fuses.

Another problem you will have in moving the consumer unit is that the switchfuse will not fit into the meter cabinet, as it is already full of other equipment. Even if the E7 gear is removed, the DNO will not allow you to put the switchfuse in the meter cabinet anyway.

This means it will have to go on the wall inside the house, in the same place the CU is now. Or you could install a second cabinet next to the first one and put the switchfuse in there. Or even put the CU in there and avoid most of the issues with moving it to under the stairs.