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.

 

[DPG]

Is anyone else seeing loads of adverts mixed in with posts today?

 

[marconi]

If you do it - I would not and I recommend you do not - then at least make the effort to wear the appropriate PPE. I have used this company to equip personnel who connect high energy density batteries for 20 odd off-grid solar applications because of the very high short circuit currents. There are many others.:

Electric Arc Flash Protection Clothing | Electricity Safety - https://www.thesafetysupplycompany.co.uk/c/4536001/1/electric-arc-flash-protection-clothing.html

And this company provides insulated tools which we use to work on the batteries, inverters and solar arrays - again there are others:

Leading Manufacturer Of Insulated Live Work Tools - https://www.boddingtons-electrical.com/

What does your professional insurance stipulate you do or do not as a skilled competent person? In the world I once worked, an industrial setting, this work had to be done by the site's Approved Person (LV) or AP(HV).

 

[littlespark]

Hypothetically, you could pull a main fuse with no load whatsoever.
Domestic, that should be easy to trace tails to any downstream mainswitch and turn off.
Clamp meter to prove no current is flowing, then yank it out.

Depending on condition of fuseholder of course......

Tinkerbell doesn't need PPE

 

[Dustydazzler]

In a domestic you can just turn off the consumer unit at the main switch and then remove the cut out fuse without load...
I do carry insulated gauntlets to wear.
I have seen guys remove tails from electric meters while still live, which imo is more risky than pulling a cut out fuse...

 

[ChrisElectrical88]

In a domestic you can just turn off the consumer unit at the main switch and then remove the cut out fuse without load...
I do carry insulated gauntlets to wear.
I have seen guys remove tails from electric meters while still live, which imo is more risky than pulling a cut out fuse...

Seen this been done aswell. Not a fan.

 

[Dustydazzler]

Seen this been done aswell. Not a fan.

I once saw a time served sparks showing a 15 year old apprentice how to remove tails from a live meter...

 

[pc1966]

The DNO folk seem to pull/insert fuses on load, but rather them than me!

As said above, at the very least make sure the load is off. Worst thing you can do on accidentally inserting a fuse carrier on high load is to brick yourself and try to pull it out.

Most of the time folk don't think too much about clothing unless facing a real threat needing PPE, and for that you get proper arc-flash tops/trousers/etc. But one thing you ought to do anyway all the time you are working with possibly live systems is to wear natural materials such as cotton - yes it will burn under serious heat, but it won't melt and stick to your skin which makes any injuries much worse. Those polyester high-vis tops are a BAD idea here!

I have no idea what the DNO use in the way of PPE as it is not my area of work. In my case I have this for general head/face protection and it has some arc-flash rating:

TC42ESBJ | Penta White Safety Helmet with Chin Strap, Adjustable | RS

uk.rs-online.com

Most gloves for arc-flash are leather over a rubber insulating type, but you do get insulating gloves that have mechanical strength and arc-flash rating, mine are:

CATU CGM-00 Mechanical Insulated Gloves (500V) - Choice of Size

Insulated below 500V Work without leather overgloves Several sizes available

www.tester.co.uk

[automerge]1598293082[/automerge]
If you are getting overalls but don't need the full arc-flash rating that some jobs demand at the very least you can look at flame-retardant ones. Some are suitable for welding, etc, and go a long way to protecting you from small incidents, for example:

Men's Dungarees - Denim Dungarees & Overalls | Dickies® UK

Shop men's dungarees, overalls, boilersuits and coveralls. Browse a range of styles in denim or canvas with fully-functional features for casual or work wear.

www.dickiesworkwear.com

But of course if your job actually means PPE is needed then you should make damn sure the correct ratings of PPE are provided for you and they are looked after!

 

[freddo]

as much as I like fuse distribution boards like the MEM EXEL for their electrical protection I don't like pulling the fuses out.

I do miss the MEM boards with the red spot-finger shock fuses, so many have been replaced now. I don't miss the Kantark stuff so much, cool to look at but it's anyones guess if the old jammed in ceramic carrier will pull out without breaking.

 

[7029 dave]

Pulling fuses on any type of cutout, without the correct ppe is dangerous, the risk is even higher with industrial/commercial cutouts with j type fuses.
Please dont do it.!!

 

[littlespark]

Pulling fuses on any type of cutout, without the correct ppe is dangerous, the risk is even higher with industrial/commercial cutouts with j type fuses.
Please dont do it.!!

We dont....

Its the fairies

 

[Grant1987]

How bright is bright? Light can be measured in units known as lux, which is a measurement of illuminance and equal to 1 lumen per square meter. To put it into perspective, a typical overcast day is about 1,000 lux. Direct sunlight is upwards of 100,000 lux. The light intensity of an arc flash 3 meters from the source is over 1 million lux, and a more recent arc flash test recorded 13.1 million lux—approximately 130 times brighter than direct sunlight! Read that, now that’s bright

 

[pc1966]

The usual arc-flash threshold for PPE being necessary is 5 cal/cm2 as that is the onset of 3rd degree burns (i.e. not going to heal to as-before EVER).

To put that in to perspective, 1 cal/cm2 is roughly equivalent to holding a lighter on your skin for 1 sec!

 

[Dartlec]

Of course a sensible Government or Governing Body would have ensured by now that the smart meters being rolled out included an isolator, as some used to I believe.

Instead we have this situation where everyone knows what happens, but nods and winks and won't ever either ban it or put it in writing where it can be done.

I was told of a mythical scheme where certain competent persons could be trained and issued their own temporary fuse seals, which would be used when replacing the fuse - and then replaced when the DNO came along to check and replace with theirs. However, UKPN had never heard of it when I approached them, and were unable to give me any good advice on how to do things 'correctly' other than to point at the regulations.

 

[plugsandsparks]

Was watching NPG install a replacement 400A fuse at his sub and he used a device which plugged into the fuse carrier to make sure there was no or low load before inserting the fuse proper. Dont know what it was but it looked a bit technical to be nothing more than continuity tester.
He also wore full head gear , face shield and apron

 

[pc1966]

I have seen (product description, not first-hand) a fuse carrier for the 400A sort of range that allows remote connection of the fuse for safety, and to have two fuses so it can auto-reclose once to reduce fault outage time.

Forget where I saw it, alas