henley block / fuse seal

[Matt Pearson]

I want to replace my csu. I notice in my leccy box that the main supply tails come up through the service fuse, which has a metal seal, through a metal block of 3"x2"x2" into the digital meter and into my csu.

It looks like I'd have to break the seal to remove the fuse to allow me to detach the main tails into the csu.

I know you probably should get permission to break the seal (they'd probably insist on a qualified electrician to do the job + resealing - just trying to save some money by DIY), but it appears very easy to be done.

Then in goes the new csu with rcd and I'm update with spare fuses.

Any thoughts though on this main tails/fuse seal issue would be welcomed.

[Sparks]

I was in the same situation not so long ago...

I rang the elec company, and they sent someone out free of charge to isolate the supply in the morning, and someone else in the afternoon to reconnect. (They took the fuse with them, so I couldn't reconnect it myself for some reason)

I took the opportunity it fit an isolator in between the CU and the meter, so if I needed to do any more work to the CU, I could just switch it off at the isolator.

The bloke that came round to reconnect me was surprised to see I had done it properly by calling them out to isolate the main fuse, and said most people just pull the fuse themselves - So I took that as it wouldn't of cause a major problem if I had simply removed the sealed fuse myself - But as it didn't cost anything for them to do it, If I were to do it again I would still call them out myself to be 100% sure!

Sparks...

[Witchy]

The first time I fitted a new CU I rang the f(r)iendly local elec board and the conversation went like this:

me: I'd like someone to remove the consumer fuse from (house) and refit next day please them: why? me: I'm going to replace the consumer unit and I don't want to do it 'live' them: are you replacing an old unit? me: yes them: oh, in that case we won't come out without a certificate me: really? How do I get a certificate? them: you need to replace the CU me: ?????

In the end I did the disconnection/reconnection live, with rubber gloves on, one hand behind my back, hair well out of the way and standing on wooden boards whilst wearing rubber soled boots. Just looking at the apparatus surrounding the street fuse gave me The Fear, so I preferred to work with the Henley block (or Lucy block in this case) instead.

Thanks NEDL., you truly are professionals.

-- cheers,

witchy/binarydinosaurs

[Colin Wilson]

Sadly, a lot of the time the service you receive depends on the banana quotient of the monkey on the other end of the phone :-}

I have daily contact with enough to fill a chimp sanctuary :-}

[Andrew Gabriel]

The risk is not only that of electric shock but also that of explosion and serious burns from accidently shorting the meter tails and forming a flash arc spraying molten and vaporised copper over you. The precautions should include eye protection (preferably full face protection), clothing which covers the rest of your skin (leather is good for this;-) and removal/covering of all earthed metelwork in the area, as well as having someone on hand (but not too close) who is familiar with CPR. Of course, this is all just such a ridiculas level of risk and pulling the fuse so much safer that you shouldn't even be considering working on live tails.

[Chris Oates]

Can't agree more Arc flash apparently kills more than electrocution

[RichardS]

ouch.

Lee's paper on arc burns makes for sobering reading.

-- Richard Sampson

email me at richard at olifant d-ot co do-t uk

[Jb]

If you have a digital meter check to see if it has an isolator built in, many of the new type have and it's there for just such a job as this

[Witchy]

I know that now :) One of the other reasons I concentrated on the henley block was that the tails were obviously fed into 2 seperate blocks several inches apart so the chances of an accidental short were vastly reduced. I'd also read (on here I think) that you can also reduce or remove the chance of an arc by making sure the new CU was completely off so there was no load on the other end.....

-- cheers,

witchy/binarydinosaurs

[Richard Savage]

Replaced both my dodgy consumer units by withdrawing the tails from the unsealed Henly block - if that is what the Bakelite box with two stacked busbars is called. I used a seriously insulated screwdriver to undo each tail in turn and then refitted the cover. Removed and replaced the consumer units and mounting board. Remade new tails and then refitted them to the Henly. All without removing the company seal.

This was all done after watching the bod from the Lecy board replace the company fuse by hammering the tar filled remains off the incoming cables (live) without any protection apart from the wooden handle of his hammer (and plenty of practice!).

BOL Richard

PS he didn't seal my Henly block.

[Witchy]

heh! I quite like watching time-served sparkies at work 'cos they do things I'd never dream of doing, like check to see if a cable's live by dragging it over the back of their hand :)

-- cheers,

witchy/binarydinosaurs

[PoP]

I do much the same thing occasionally, but instead of over the back of my hand I just swipe the cable with my finger - making sure I've got enough momentum in my hand to take it off the power quickly should it be live.

Works for me.

PoP

Sending email to my published email address isn't guaranteed to reach me.

[Witchy]

Doesn't it hurt every time? Last time I got a bolt was when I was wiring up the 2nd of a pair of 2-way switches and I forgot it was live and one of the lives was touching the metal back box before I wired it up :-| Remember it vividly!

-- cheers,

witchy/binarydinosaurs

[PoP]

No. I forgot one instruction from my last message. I triple-check that the mains is off before I test the wire for live. I'm not stupid ;)

Mind you, I got a little taster not long ago. I was up an aluminium ladder in someone's lounge sorting out a light fitting. Silly me touched the permanent live. Not directly, but as I was twisting the light fitting (metal of course!) the permanent live came loose.

I climbed down the couple of steps of the ladder so fast I can't remember having climbed down :)

PoP

Sending email to my published email address isn't guaranteed to reach me.

[Witchy]

That's what I mean though - the sparkies I know just check anyway! Even the youngsters. No wonder most of 'em don't have much hair.....

Heh!

-- cheers,

witchy/binarydinosaurs

[Dave Liquorice]

Nor me then. B-)

I tend to check the circuit I'm going to work on is live, volt stick these days was a neon screwdriver, pull what I think is the relavant fuse, check again, then start work gingerly checking with the fast moving finger that the "live" wire really is dead. Possibly a few times getting slower just in case the first time was to fast.

[Chris Oates]

we make everyone carry these

contact !

[Dave Liquorice]

What did I say? Doh!

All the same even with volt stick I still cautiously check that the wires are dead. I suspect a voltstick wouldn't detect a (relatively) high impedance leakage that could still make for a nasty jolt.

[James Salisbury]

Err What about MICC? I have seen the aftermath of a burgular alarm installer who checked with his volt stick, then put in his cable clips, tap tap tap BANG !

[Lurch]

If you were to read the instructions it says that.

SJW A.C.S. Ltd.