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?

 

[Strima]

Having done the G39 course I'm now very wary of pulling a fuse in a domestic scenario even with the correct PPE.

Commercially we always arrange for MOCOPA accredited persons to do it as the customer gets paid for it anyway unless they are un-metered supplies such as street lighting etc. I'mm ore than happy to let someone else take the risk.

A lot of the bigger sites we work on have dedicated facilites maintenance teams who sort all this out anyway with many outages taking place out of hours so the supply is already dead when we get there in the morning.

 

[Ian1981]

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?

On the cast iron cut out query, Clients in my experience have basically said that they can’t afford the down time in having one changed where the premises is 24hr occupied so they never get it replaced, now whether or not the DNO have insisted it’s changed as it’s their equipment , I don’t know.

 

[davesparks]

On the cast iron cut out query, Clients in my experience have basically said that they can’t afford the down time in having one changed where the premises is 24hr occupied so they never get it replaced, now whether or not the DNO have insisted it’s changed as it’s their equipment , I don’t know.

I'm currently dealing with places which are still on lockdown, it's the ideal time to get this stuff sorted, but UKPN seem to be allergic to answering the phone.

 

[Fitzy]

You should never, ever pull the main fuse, unless its a matter of urgent life or death situation. During my training, my tutor showed us a video of a test facility, where they pulled the main fuse with a special machine and the carrier had an unseen crack in it, so as it was pulled, the machine's 'fingers' touched the exposed metal contacts and 'BANG', a massive arc of bright light and the mechanical 'fingers' where either blown off or fused together. Imagine what that would do to flesh?

 

[davesparks]

Having done the G39 course I'm now very wary of pulling a fuse in a domestic scenario even with the correct PPE.

Even without a course I'm very wary of pulling fuses, as much as I like fuse distribution boards like the MEM EXEL for their electrical protection I don't like pulling the fuses out.

Using a plasma cutter helps you realise what even a tiny amount of current can actually do to a piece of steel.

 

[pc1966]

I agree, inserting or removing fuses on load gives me the willies and I happen to have some PPE (not the full stuff, only good to something like 4 cal/cm2 for hat+visor and 12 for insulated gloves).

And that is before considering old decrepit cut-outs that want to crumble when touched!

 

[HappyHippyDad]

Having done the G39 course I'm now very wary of pulling a fuse in a domestic scenario even with the correct PPE.

Commercially we always arrange for MOCOPA accredited persons to do it as the customer gets paid for it anyway unless they are un-metered supplies such as street lighting etc. I'mm ore than happy to let someone else take the risk.

A lot of the bigger sites we work on have dedicated facilites maintenance teams who sort all this out anyway with many outages taking place out of hours so the supply is already dead when we get there in the morning.

Can you expand a little please Strima with regards the outcomes of pulling a fuse that you saw in your course?

 

[plugsandsparks]

I generally dont automatically rule out pulling fuses, being commercial and industrial. Although anyone attempting it with bare hands and without eye and face protection is running the gauntlet....
I do remember a couple of EICRs i was doing and you could clearly see the exposed screws on the fuse carrier as the little bit of insulation was missing, grabbing that with bare hands would have been a day to remember. Oh that was a C1 and stopped the EICR in its tracks..
Another was an old fuseboard mounted high up with exposed busbars, broken carriers, bare lugs etc. Totally refused to even look at it as even to prove dead was a risk... lol

 

[pc1966]

Can you expand a little please Strima with regards the outcomes of pulling a fuse that you saw in your course?

Probably something like this:

View: https://www.youtube.com/watch?v=Z3yKFLJpnhI


They had proper PPE and appear to survive OK, not sure their underwear would say the same.

 

[Zerax]

What's the name of that company that the infamous David Savery often promotes for fitting isolators ?

 

[Strima]

Can you expand a little please Strima with regards the outcomes of pulling a fuse that you saw in your course?

On some cutouts there's an issue with insulation creep where the line conductor insulation has shrunk back and there's only a small air gap between that and the neutral cores on the split concentric cable. Not noticeable until you disturb it and everything vaporises in your face. I'm led to believe this is as recent as early 2000's that this cable was used as the problem didn't arise for a few years.

That small length of cable produces a very large, hot & fast moving cloud.

Minimum PPE is suitable face-shield, double layered insulated gloves and flash proof coveralls.

Even after an arc fault has occurred there's still further risk due to auto-closing devices at the substation so it may well go bang again.

Also when working on the cutout all terminations should be checked for tightness same as we do within a DB.

 

[FatAlan]

What's the name of that company that the infamous David Savery often promotes for fitting isolators ?

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

 

[R-fur]

On some cutouts there's an issue with insulation creep where the line conductor insulation has shrunk back

XLPE insulation creeps back, a number of companies have stopped using it because of this.

 

[ChrisElectrical88]

I will pull them in a domestic house, if absolutely necessary. I have done my ERG39 course with Scottish power, all be it that was for street light cutouts but same risks I would imagine.
It’s just a non starter getting someone from the DNO to come and pull a fuse. Luckily most new builds now have isolators.
On non domestic boards I will rarely pull the fuse, although I did last week where the seals were missing, obviously no under load to change a TP board in a small commercial unit.