Submain breaker/fusing

[RF Lighting]

Let me guess, It's a metalclad switchfuse in your meterbox?

If PME earthing is available on your supply, then it's best to have the upgrade, and will save a lot of work for you too. You will however have to ensure that main earthing and protective bonding conductors are big enough for the new earthing system.

If PME is not available and you have to stick with TT, your best bet is to install a mini PLASTIC CU in your meterbox, with the armoured terminated into it and the gland / armour earthed with a piranah nut or similar.

In the CU terminate the meter tails direct into a 100mA type S RCD, which in turn supplies a type C 63A MCB to feed the submains to your house CU.

This same RCD can also cover the new T&E submains too by supplying it from an MCB in your house CU. Something like a 50A MCB would be ideal to provide discrimination from the 63A MCB in the meter cabinet.

Then RCD protect all the other circuits with 30mA non time delayed RCDs. Either a dual split type CU or each circuit protected by a DP RCBO.

 

[mbga9pgf]

Let me guess, It's a metalclad switchfuse in your meterbox?

If PME earthing is available on your supply, then it's best to have the upgrade, and will save a lot of work for you too. You will however have to ensure that main earthing and protective bonding conductors are big enough for the new earthing system.

If PME is not available and you have to stick with TT, your best bet is to install a mini PLASTIC CU in your meterbox, with the armoured terminated into it and the gland / armour earthed with a piranah nut or similar.

In the CU terminate the meter tails direct into a 100mA type S RCD, which in turn supplies a type C 63A MCB to feed the submains to your house CU.

This same RCD can also cover the new T&E submains too by supplying it from an MCB in your house CU. Something like a 50A MCB would be ideal to provide discrimination from the 63A MCB in the meter cabinet.

Then RCD protect all the other circuits with 30mA non time delayed RCDs. Either a dual split type CU or each circuit protected by a DP RCBO.

I doubt there is space for that now after 2 days work to relocate the CU, plus he is going to need another day for testing in the future, 600 quid total for what isincreasingly sounding like a botched job.

Its been sightly modded since, but this is what it looked like after day 1:

Untitled

• mbga9pgf
• 9 Mar 2011
• 1

I reckon a DP 80a 100ma S type below the meter then to the KMF switch fuse will do the job. I can use the one currently installed in the CU (incorrectly I believe, both sides should be 30ma versions nowadays to protect ccts). I will then install another KMF upstairs to where the 25mm SWA splits with a 63a fuse in place.

Looks as if I will be pulling the service fuse again then...

 

[westie101]

Looks as if I will be pulling the service fuse again then...

 

[RF Lighting]

That adaptable box needs altering too, as live and neutral enter through seperate holes which is not allowed.

 

[RF Lighting]

Also, whats the big plastic box in the middle of the cabinet there for?

 

[mbga9pgf]

Also, whats the big plastic box in the middle of the cabinet there for?

Was put there temporarily.moved following day to where the metal adaptable is to house 2X100a henley blocks to join the 25mm SWA and the tails. At that stage was purely there to house thejunction between 2 2.5mm cables. Overkill, but its all he had at the time.

Would you agree getting the lad to put in an s type RCD between the meter and the KMF would solve most of my problems? I dont want to **** the spark off, we all make mistakes, but I would rather he sort it than me seeing as its his pen on the sheets. I can deal with stuff downstream of the CU, new finals etc, what I dont want to do is b*gger round with tails straight from the meter.

 

[mbga9pgf]

That adaptable box needs altering too, as live and neutral enter through seperate holes which is not allowed.

Why not may I ask?

Also, how best would I approach the chap about putting it right? There is nothing worse than someone telling you your job. He did, bar the pretty big f*ck up with the RCD protection on the tails, a very good job IMO, so how can I avoid ruffling his feathers?

 

[RF Lighting]

I'm confused. Does the SWA now terminate into the plastic adaptable box, and the metal one has been removed or something else?

If it'll fit then you could install a type S RCD between the meter and the KMF.

If not, replace the KMF with a mini CU as I described above.

Regulation 521.5.2 does not allow it. It is because in an AC circuit current flow produces a magnetic field around the wire. If this wire is passed through a hole in a ferromagnetic enclosure, and it's neutral and protective conductor(s) through another then an eddy current can be induced into the metal.

 

[westie101]

One of these days the REC is going to come along or be asked to change that board - boy will that be fun!
In normal circumstances an ODVC is for REC equipment only!

At least up here it is!

 

[mbga9pgf]

I'm confused. Does the SWA now terminate into the plastic adaptable box, and the metal one has been removed or something else?

If it'll fit then you could install a type S RCD between the meter and the KMF.

If not, replace the KMF with a mini CU as I described above.

Regulation 521.5.2 does not allow it. It is because in an AC circuit current flow produces a magnetic field around the wire. If this wire is passed through a hole in a ferromagnetic enclosure, and it's neutral and protective conductor(s) through another then an eddy current can be induced into the metal.

What I meant was, the metal adaptable was swapped out for the plastic enclosure the day after, with another smaller adaptable where the current (big) one is currently. As the new adaptable is plastic, I take it induction will not be a problem?

Finally, bearing in mind I want to up the supply to 100A in the near future with the DNO, will it be worth getting a seperate KMF installed to the 16mm where the 25mm is split into the main CU and the 16mm? If there is RCD protection at the meter box, I may be jumping to conclusions here, but there should be no requirement for one after the henley blocks, as the one you are suggesting between the meter and the KMF in the picture will pick up any inbalance between phase and neutral?

 

[mbga9pgf]

One of these days the REC is going to come along or be asked to change that board - boy will that be fun!
In normal circumstances an ODVC is for REC equipment only!

At least up here it is!

Well, if you want to suggest how I am supposed to do that with rec requirements for a switchfuse with all tails >3 metres, be my guest... same with a tt supply and associated earth blocks...

Bearing in mind a month ago, I had a plastic enclosed CU in the meter box, with all circuits routed up the wall cavity, what we have now is certainly an improvement.

The rec is going to be asked to come along soon enough anyway, seeing as they have a 0.6 ohm value between their overhead line and neutral. I am starting to get a little P*ssed at dimming lights every time the shower goes on with an associated 25 volt drop in supply.The fact the nearest tranny is 200 metres and the overhead cables are as thick as a bootlace doesnt help. Oh, they cant shake the fact the written agreed capacity is 17KVa either....

 

[westie101]

If your REC is happy with it, fine.

I assume there is nowhere within 3m to fit a point of isolation, without putting your own ODVC alongside or above

 

[mbga9pgf]

If your REC is happy with it, fine.

I assume there is nowhere within 3m to fit a point of isolation, without putting your own ODVC alongside or above

To be honest, I didnt ask. Seeing as they have been notified 3 times of a door that is hanging off the meter box with no engineer. Unfortunately, the only point would be upstairs by the henley block, which is pretty pointless.

 

[westie101]

Seeing as they have been notified 3 times of a door that is hanging off the meter box

The responsibility to keep it dry is yours*, so as I see it you've installed a lot of equipment in a situation where it could get wet if the door falls off!

*thought the REC's gave these boxes away the T&C's of supply made the customer responsible for the ODVC. We for years would replace door & boxes if they were damaged (I know often because the meter reader did not close the door properly)
All this work is now chargeable to the customer

 

[mbga9pgf]

Seeing as they have been notified 3 times of a door that is hanging off the meter box

The responsibility to keep it dry is yours*, so as I see it you've installed a lot of equipment in a situation where it could get wet if the door falls off!

*thought the REC's gave these boxes away the T&C's of supply made the customer responsible for the ODVC. We for years would replace door & boxes if they were damaged (I know often because the meter reader did not close the door properly)
All this work is now chargeable to the customer

How nice. At least I will have the comfort in knowing I wont be paying the miserable money grabbing B*stards for pulling the Service fuse and resealing it then.