General risk work on mains

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Dan L
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General risk work on mains

Post by Dan L »

It's my understanding that the following examples of work are general risk.

- moving a main switch to a different position on the switchboard to make space

- installing a new mcb on mains or isolation point for example adding overcurrent protection mcb at outside meter box.

. Generally working on mains is high risk if its not low risk. The examples are not low risk as its new work on the mains.

Can someone please elaborate on this / correct me

Thanks
AlecK
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Re: General risk work on mains

Post by AlecK »

1 - moving a main switch to a different position on the switchboard to make space

Low risk. Nothing new is being installed; and no alteration to the circuit config or that affects protection.
It amounts to maintenance of the installation rather than an alteration


2 - installing a new mcb on mains or isolation point for example adding overcurrent protection mcb at outside meter box.

High risk.
Something is being added that's connected to "mains"; and that isn't within the exclusion that says installation of revenue metering (which includes load control eg ripple) isn't "mains work".


3 . Generally working on mains is high risk if its not low risk. The examples are not low risk as its new work on the mains.

Yes "mains work" is high risk unless low risk.
Except for installing meters, which isn't "mains work" despite being the installation of fittings connected only to "mains";
and therefore is work on mains that's classified as general PEW.
IMO; that exclusion is just silly; 'cos clearly it IS "mains work".
What they should have done instead is to exclude it from being classed as "high risk"
Dan L
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Re: General risk work on mains

Post by Dan L »

I see.

Maybe that's why it didn't make sense to me because it was not correct

Seems iv been mis informed.

Thanks.
AlecK
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Re: General risk work on mains

Post by AlecK »

The most important but is that "mains work" - or any other type of PEW listed in 6A (2) as being high risk - can only be high risk if it isn't covered by clause (1).
Many people seem to struggle with that concept.
They ignore the words "not being low risk PEW", and assume that everything listed is always high risk.

There are also 'local rules" in some places; where networks go beyond what the ESRs require and impose additional requirements.
For example, replacing a mains entry box, or even the entire mains, us clearly replacement of fittings and therefore is low risk PEW.
No CoC required, let alone RoI; just an ESC.
But some networks insist on inspection for this work, and even that the inspection must be by an inspector approved by them.
They justify this on grounds of risk of transposition of A & N; but transposition is easily picked up by normal testing.
And they couldn't be held accountable for it anyway: as their only involvement is typically safety isolation and - on completion - re-livening.
JamieP
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Re: General risk work on mains

Post by JamieP »

Just in response to your last comment I agree replacing mains is low risk, or any other replacement for that matter but isn't such a task seems quite hard to complete due to the fact I'd think it's only replacement if it was the same length, same route etcetc, any changes in this would to me make it new work and installation

Just curious on your thoughts around things like this such as any cable "replacement", I've seen people re run cables or mains and call it a replacement when they have run the new cable in a different route, sometimes shorter and better overall but to me it stops being a replacement, as mentioned, obviously some things are very easy to tell when it's replacement but with cables, not so much, what are your views on the demacation between the two?
AlecK
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Re: General risk work on mains

Post by AlecK »

This is something that is open to a fair but of interpretqation.

Some degree of movement / relocation of conductors is certainly permitted; because 6A(1) clearly allows for "relocation or extension of a conductor" for purposes of "facilitate replacement of a fitting".
Remember the conductors are fittings too.
So as well as allowing for eg moving existing conductors when replacing a mains switch or a mains entry box);
this can also be applied to (minor0 relocation / extension as part of replacing the mans conductor itself.

How far that an be taken is up to the person certifying.
But in my view replacement of mains, along substantially the same route, between substantially the same points, has to be accepted as 'replacement'.
If either end-point changes significantly; then more likely to be an alteration.

Doesn't matter if the new conductors are of different size.
Used to be that replacement with larger conductors was listed as work requiring inspection; but those Regs were revoked long ago and don't carry over.
Doesn't matter that the new conductors may be of a different type ( conduit replaced with TPS or N/S; or single-insulated single aerials replaced with N/S).
And doesn't matter if the supply fuse is changed-up to a higher rating.
All that matters is that the CCC is adequate (in the as-installed conditions); and that the protection is suitable.
Plus we have to apply ESR 13(1); and not make any part of the installation not worked on any less safe than it was.
So we need to consider the effects of eg larger mains conductors on PSSC at MSB.

WRT old rules; the words I live by were in the original ESR 66 when first published (2010).
Certification was not required for "(d) the replacement of any fitting with a fitting of appropriate size, type, and rating for the electrical circuit" .
True those words have been revoked, so have no legal status any more.
But they represent the clear intention of what work should be certified under ESRs (as against under earlier Regs); and that intent hasn't changed.
All that's changed is the concept of risk categories was introduced, and in that process the words were lost.

Note that the person who gets to decide is the person who does the work.
No-one else gets to second-guess that decision; except by making a complaint to EWRB.
Except that - as already noted, some networks have invented their own rules; and in some (but not all?) cases they have made these extra requirements part of the contract between them and their customers -which makes them commercially enforceable; outside of ESRs.
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