Pulling cutout fuses

[davesparks]

We see a lot of threads asking what to do about isolation for a CU replacement with lots of talk of the seal fairy and just getting on and pulling the fuse.
It gets me wondering whether you do the same outside of the domestic world?

Does the seal fairy visit the heavy duty (over 100A) cutouts as often in your experience?

And another related question, do DNO's replace larger cast iron cutouts as a rule the same way they do in domestic?

 

[HappyHippyDad]

How about pulling BS3036 fuses. Does everyone always switch off the main switch of the CU before pulling one of these fuses as you'll never be able to make sure you are not pulling the fuse under load otherwise?

 

[pc1966]

Certainly I would always switch off before removing or inserting BS3036 fuses. They are even worse as if it blows on insertion there is nothing to contain the plasma formed from the fuse wire blowing!

 

[Vortigern]

I am definitely of the school of don't touch the cut-out/DNO/metering equipment. I think we all know the dangers if something goes wrong and boy does it ever go wrong when it does. It's not just the cut-out that presents a danger but also the cable and its' state which may short out if manipulated via the cut-out.
Having said that...I had a new three phase cut-out replaced by the DNO and they left. As the smart HH meter had been disconnected, even though they reconnected there was no live out of the meter. Phoned them and they re-attended. They took out the fuse and tested as I would not, and said why didn't I take out the fuse. I said it's illegal to which they tsked tsked and gave knowing looks and suggested it would have been ok for me to do that. So go figure!
I would definitely no way touch anything above domestic 100a, instinct alone forbids it.

 

[Dartlec]

I think it’s Haste. I tried calling them to do an isolator but they didn’t cover my area which is SSE.

I've been meaning to contact them since I saw it in one of his videos so emailed them last night, but apparently they don't offer that service any more and just suggested I contacted my local distributor

 

[Gavin John Hyde]

It's a funny one around here as I literally straddle 2 dnos. I just moved out of Bath to Peasedown. western power say don't pull fuses at all yet SSE say if you are in a scheme and it's a single phase upto 100a domestic only property you can pull fuse they will even give you seals to put back on afterwards. If fuse looks old or damaged give them a call.

 

[pc1966]

SSE say if you are in a scheme and it's a single phase upto 100a domestic only property you can pull fuse they will even give you seals to put back on afterwards. If fuse looks old or damaged give them a call.

The voice of sanity!

 

[Lucien Nunes]

With an HRC such as a BS1361, closing onto a fault should cause a rupture within the cartridge and hopefully no arc outside of it. Therefore the greater risk is drawing an arc at the carrier contacts by pulling it under load and more so under fault conditions. I like to position it ready and then push it home into contact with a closed hand so that if anything goes wrong and I recoil, I won't take the fuse back out unintentionally. To pull it under (normal) load is a matter of being very swift and certain, assuming the design is not prone to arcing over to the casing etc.

How about pulling BS3036 fuses.

With a rewirable (and there were rewirables before BS3036) there is also the risk of an arc in free air if the fuse ruptures when closing onto a fault, or if a fault occurs when the covers are off. There are some traps for the unwary, e.g. on a metalclad Wylex, a plasma bridge can form between the bottom (unfused) terminal and the edge of the aperture in the front panel which would normally be intercepted by the lip on the plastic cover. With a professional hat on, I would therefore never choose to handle these fuses live.

With my historical hat on, I might have been seen to insert channel fuses on a live circuit. That's the type where the fuse wire lies along an open channel facing the user and comes flying out at you when it ruptures. Needless to say, these things were invented when typical fault currents were very much lower than they are today.

 

[freddo]

With my historical hat on, I might have been seen to insert channel fuses on a live circuit. That's the type where the fuse wire lies along an open channel facing the user and comes flying out at you when it ruptures. Needless to say, these things were invented when typical fault currents were very much lower than they are today.

Here is some photo of a glass fronted fuse box with those fuses, I don't know where this was removed from:

 

[telectrix]

personally I prefer to pull the tails out of meter live. less chance of any problems with a cut'out fuse. (obviously after ensuring that there is no load on the installation). L out first, then N. N in first, then L.

( substitute "I" for "a spark that I know")

 

[pc1966]

personally I prefer to pull the tails out of meter live. less chance of any problems with a cut'out fuse. (obviously after ensuring that there is no load on the installation). L out first, then N. N in first, then L.

( substitute "I" for "a spark that I know")

The least-worst option if the cut-out is old and dodgy and it simple has to be done then.
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But obviously not something any of us would ever recommend...
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Here is some photo of a glass fronted fuse box with those fuses, I don't know where this was removed from:

I have seen photos of other Tucker Telac fuseboxes and they are works of art really. Just not something you would want to encounter live these days!

 

[Lucien Nunes]

That box is nice, Freddo, because it's an 8-way. Many 2 / 3/ 4 way boxes survived because they were used in so many homes, but 8-way are rare and its great that this one has been saved.

 

[AJshep]

I recently was called out to look at a possible rewiring job, The customer had someone in to do some work in the bathroom (6 months prior) as part of that work they changed to consumer unit and put an Earth stake in.
Anyway the consumer unit was a mess, you could tell the previous electrician didn't quite know how to fit a new mantel unit and as a result he got himself in a bit of bother...
I'm not quite sure of the series of events but I was curious to why the previous electrician had put a rod in, I could see it would have been an TNS supply, I also noticed that I could see evidence of superglue around the rear of the cutout....
Its not obvious but when you look carefully at the picture you can see the whole cutout has dropped and its not fixed.
It was then I noticed scorch marks on the bottom of the mantel unit...
I believe the previous electrician pulled the fuse and shorted the incomer to the mantel unit, possibly losing the suppliers earth at the same time...

Fortunately I noticed this as if I had just gone in and pulled the main fuse I would have been in serious trouble, but this has definitely changed my view on pulling main fuses.

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Pictures of afterwards to save the customer costs I re-used the old unit, I know its not the neatest.
The DNO came after I'd finished so when I csme back to connect the suppliers earth up so I left the 100ma Upfront RCD in.

 

[pc1966]

Fortunately I noticed this as if I had just gone in and pulled the main fuse I would have been in serious trouble, but this has definitely changed my view on pulling main fuses.

Yes, a lucky escape there. As you say, something to be very cautious about doing.

Pictures of afterwards to save the customer costs I re-used the old unit, I know its not the neatest.

It is still a huge improvement!

The DNO came after I'd finished so when I csme back to connect the suppliers earth up so I left the 100ma Upfront RCD in.

No harm in that.

 

[telectrix]

as above, a huge improvement, even though it'd protecrap.

 

[AJshep]

Thanks @pc1966

as above, a huge improvement, even though it'd protecrap.

Thanks guys. Proteus and M2 are terrible. not a CU I would have chosen, its not one that I'd be advertising.