Meter room for new block of flats

NoSparks · Aug 23, 2015

For a new block of flats I am considering locating the meters in a meter room. Our suppliers now fit 100A cutouts after each meter. From each meter cupboard I want to run 25mm SWA (or the braided 25mm cable, watever this is called) to the consumer unit inside each flat. Now the cable entering the cutout needs to be standard 25mm "tails" The question is how best to join the "tails" to the SWA. The obvious answer seems to be to use a phase block inside a metal enclosure but this seems messy. Are there any better solutions?

7029 dave · Aug 23, 2015

I am a bit lost with your terminology, but the answer to question, term the SWA into an metal clad switch fuse.

malcolmsanford · Aug 23, 2015

If as I read you rightly you are going to have x amount of heads in a cupboard and x amount of distribution circuits to you CU in each flat.

I personally would not want to I would think you are exceeding 3mtrs and I doubt if your DNO will allow you to use their fuse as the protection device for the SWA.

Personally I would either fit a Ryefirld board if there are only a few flats then indiviual switch fuses

Stu1312 · Aug 23, 2015

Who is your meter operator as I don't know any that install a cut out after a meter. Nearly all will fit a double pole isolator after the meter but that is your lot.

Darkwood · Aug 23, 2015

I'm too a liitle confused here, regardless of the DNO's fusing arrangements although your described set-up is confusing, you still need to give upstream protection for the flat supplies, can you expand on exactly what you mean when you say the DNO's cutout is after the meter?

Also can you explain how your going to ensure the submains cables are protected or have the DNO fitted SW/F for the use of the customer?

marc8 · Aug 23, 2015

hi Nosparks

been doing these over last year or so, if uk power networks then as follows.

install switch or switch fuse

install Ryefield or similar

we used 150mm metal box trunking around system, BI rated cable between head & Switch/switch fuse.
same between incoming switch/ switch fuse & Ryefield panel.
singles through to switch fuse for each flat & don't forget you now have to install the meter board aswell.
then terminate armour cable to switch fuse for flat.
also we used earth connection point to terminate all earth points & away from there.
you will need to size the incoming main for sizes of switch ect.
we then double insulated as the singles came through the box trunking into the meter location & they have all been connected.
one just done 46 units & landlords in same room.
but you could do laterals & use riser cupboards.
good luck
you don't have to supply a switch or switch fuse at the first point but in uk power networks information it uses the words STRONGLY ADVISED.

tazz · Aug 23, 2015

You should put a photo up of the last job Marc, The meter room looked very professional & neat when I saw it last week.

Stu1312 · Aug 23, 2015

If you're doing the installation of the ryefield as well, get a copy of G87 as it covers the requirements for multi dwellings, also worth reading mocopa guidance if you are pre installing cabling for the metering as mocopa has requirements for cable colouring that most people get wrong.

marc8 · Aug 23, 2015

tazz said:
You should put a photo up of the last job Marc, The meter room looked very professional & neat when I saw it last week.

Hi Tazz
will try & get pictures for Wednesday & put them up cheers

NoSparks · Sep 26, 2015

HI, Thanks everybody for your responces. Yes I did get the terminology wrong, after the meter it is of course an isolator.

Following this thread I did followup the references particularly G87 and it has helped considerably. I also spoke to the DNO (not that much use) but one thing came to light. If the service fuse blows then you have to wait for the somebody to come out to replace it, however if you have a seperarte switch fuse after the meter a blown can be replaced by any electrician. A problem arrises if both are 100A or both 60A in that there would be no discrimination, so my plan now is to have the Lucy box fitted with 100A fuses and the switch fuses with 60A which is more than adequate for these small flats.

Darkwood · Sep 26, 2015

NoSparks said:
HI, Thanks everybody for your responces. Yes I did get the terminology wrong, after the meter it is of course an isolator.

Following this thread I did followup the references particularly G87 and it has helped considerably. I also spoke to the DNO (not that much use) but one thing came to light. If the service fuse blows then you have to wait for the somebody to come out to replace it, however if you have a seperarte switch fuse after the meter a blown can be replaced by any electrician. A problem arrises if both are 100A or both 60A in that there would be no discrimination, so my plan now is to have the Lucy box fitted with 100A fuses and the switch fuses with 60A which is more than adequate for these small flats.

In the event of a short circuit your fuses will only give partial discrimination, usually DNO use type III upwards against say your Type II so this can favour the customer fuse to blow but its not guaranteed. When the Supply is only 100amps then its not usually possible to get full discrimination, and may only achieve it against 6 and 10amp rated mcb's against the 100amp DNO fuse.