New CU & Supply type

[FredFlintstone]

Hi Fred, hows Wilma.

Have been reading your post and am wondering how the Local building control inspection business works.

Am looking at doing a CU change in my house in the future and would like to do as much as possible myself.

My dads mate is a time served spark but is not Part P certified. He knows what he's doing and would be able to do anything i wasn't to keen or sure of doing. I had thought that you had to get a part P certified spark to do the works or can you do all the work and get it tested/certifed by Building control before getting the Lectric board to move the meter tails.

Hi Teahead,

Good question. As it stands, it's a farce and every LA has a different interpretation of the rules and tus a different policy re inspection.

My LA stated that I need to notify them (which I did - £58 or thereabouts) and then, if the installation was carried out by an electrician with G&G quals then they complete the form and provide a copy of their certificates. If it was not carried by a qualified electrician then the installation needs to be inspected by a qualified (again to C&G) electrician and signed off. At no point did they say a BC officer would attend. I challenged this and stated that my £58 covers the notification and inspection and under no circumstances could they expect me to pay for a qualified spark to inspect- if they want a qualified electrician to certify then it's at their cost - my fee's been paid.

As it happens, if they just send a BC officer round to inspect without testing then I am going to pay for a test but but if they test then all the better - savces me cash.

If your Dad's qualified then you should be fine - call your local LA and ask what their procedure for such work is.

P.S. Wilma's fine thanks. Getting older and gravity taking its toll but she's still fine.

 

[FredFlintstone]

electrocution & facing the wrath of the DNO.

"Or"

LOL.

 

[FredFlintstone]

Cheers folks.


I figure removing the main fuse will cut the supply but also figure switching off the Cu main switch first would be a good idea - I don't know if just pulling the main fuse without switching of CU would do any harm but think it would be safer to have no load on the CU when the fuse is pulled.

Are there any hazards involved with pulling the fuse or disconnecting and reconnecting the meter tails with the main fuse out?

Just to add, the fact you've already considered this shows you should be able to cope with sorting out the rest...

It is a good idea to isolate the CU first, that will reduce any possibility of arcing when you remove or replace the fuse.

It is best to remove or replace the fuse quickly and firmly, rather than levering it out gently - again to reduce any risk of arcing.

Good luck

Gavin

Like I say, I've done plenty of research so know the basics. Still learning and probably always will be but the only way to learn is by practical application. All the research and reading in the world is all very well and fine but unless you put new found knowlege into practice the knowlege is useless.

ARCING - That's the word I was looking for. I first experienced this a couple of years ago when a cartridge fuse blew in my old house, knocking out all the power downstairs. I had no fuses so needed to swap fuses between holders between upstairs and downstairs in the morning and evening. All was fine the first time I swapped them but when I tried it again in the morning I got a bit of an arc as I pulled the holder open. It was only a little blue flash but I pood my pants all the same - little blue flash or big blue flash - it can still kill you!

It's the arcing I was worried about which is why I figured I'd switch the CU off first.

 

[scousespark]

the arc i'm talking about is if you break the fus connections, in which case your little blue flash will bring with it something like 16,000 amps and your next chat will be with St Peter along the lines of "so there i was just pulling with my pliers and....."

 

[bernardgreen]

the arc i'm talking about is if you break the fus connections, in which case your little blue flash will bring with it something like 16,000 amps and your next chat will be with St Peter along the lines of "so there i was just pulling with my pliers and....."

If it was little blue flash it would be a bit less than 16,000 amps.

Can you explain why breaking the circuit by pulling the fuse results in a massive current surge while breaking the same circuit with the main switch does not result in this current surge ?

 

[securespark]

electrocution & facing the wrath of the DNO.

"Or"

LOL.

i didn't mean consecutively....

 

[ELZ4742]

the arc i'm talking about is if you break the fus connections, in which case your little blue flash will bring with it something like 16,000 amps and your next chat will be with St Peter along the lines of "so there i was just pulling with my pliers and....."

If it was little blue flash it would be a bit less than 16,000 amps.

Can you explain why breaking the circuit by pulling the fuse results in a massive current surge while breaking the same circuit with the main switch does not result in this current surge ?

also, surely the fuse would pop everytime it would be pulled wouldnt it? no?

 

[FredFlintstone]

I can see the potential issues - If I pull the fuse and an arc occurs then the arc could be between the incoming supply and me rather than the incoming supply and the fuse with obvious consequences. I'll just have to be careful.

Thanks for all your help and advice on this one everyone. Much appreciated.

 

[scousespark]

I am trying to point out the danger of breaking the cut-out and generating arc current. This doesn't happen often, but it is a possibility. I haven't experienced it myself but the spark who taught me had. He was working for a DNO so was wearing the fully protection kit (gloves and visor).
The problem comes when the live terminals break and you have 230V with very little resistance and the casing is energised. It's rare so the fuse doesn't always pop.

It just seems strange that there doesn't seem to be much concern in this thread that the OP is about to do something which, as a trained/time-served spark, I've had drummed into me is risky. Maybe I'm just too safety-concious.

 

[davelx]

If there is no current flowing when you pull the fuse, there is no reason for there to be any arcing. And if you have turned off the isolator (s) in the CU(s) then there will be no current flowing, so there cannot be any arcing.

 

[scousespark]

I'm talking about possible shorts when you start pulling older fuses.
If you break the fuse holder, you can get a short-circuit, which has nothing nto dow with the downstream load. As I've said this is rare, but not impossible. Why do you think the DNO wear such thick gloves and visors.

 

[bernardgreen]

I am trying to point out the danger of breaking the cut-out and generating arc current.

Yes there is a danger of the fuse and incomer termination assembly falling apart when it is touched and that would be very nasty as it could mean a dead short across the incomer. But it is a small risk with modern plastic boxes that have not been damaged and show no signs of damage.

With a bit of experience it is possible to make a reasonable judgement as to whether in dire emergency the supply fuse could be removed without it falling to pieces.

I have to say when the meter here was replaced the fitter pulled the fuse with a bare hand while standing on wet ground. But this incomer is only 26 years old.

It just seems strange that there doesn't seem to be much concern in this thread that the OP is about to do something which, as a trained/time-served spark, I've had drummed into me is risky. Maybe I'm just too safety-concious.

There is concern and the advice is NOT to do it.

 

[FredFlintstone]

Thanks everyone and thanks for the concern.

I understand it's not the done thing, especialy for a DIYer and your advice is noted.

The meter is actually fairly new - I don't know when it was changed but I'll check the sticker under it. Whe it was changed the guy must have pulled the fuse to do so because there's no isolator. Granted - he's a pro and may have been wearing protective gear but it must have been in OK condition then.

 

[scousespark]

Cheers Bernard. All I've been saying is that this is not something a spark should be advising a diyer to do. Looking at the original pictures it looks safe enough, but there is a safer option for Fred in that he can get a DP iolator fitted which means he never has to open the fuse holder.

It sounds like Fred has decided to go ahead, so good luck mate.

 

[FredFlintstone]

It sounds like Fred has decided to go ahead, so good luck mate.

Not necessarily Paul. Contacted my supplier and they quoted about six weeks. Going to contact the DPO directly and see if they can do it quicker. I know they do the work upon instruction from my supplier anyway but wondering if I pay them directly rather than my supplier paying if it will be any quicker. Can't imagine it being much more than £50.

Hey, if I really stuff things up (and am still alive) I'm not too far from you - just over by Delamere. Could be a good job in it for you (although I hope not) although you've probably got more than enough work locally. I used to live in Huyton until not too long ago.