Swa earthing and coding

dave992 · Dec 1, 2021

Hi all, we have a much discussed topic. Swa and the earthing of the amounting through a fly lead. What your thoughts and how would you code an Swa cable, the amouring is the cpc and no fly lead been taken too the earth bar (the Swa been terminated into a metal container)

So are saying code 3 as the circuit test results are within and on the other hand we have people coding 2, as no fly lead been take to the earth bar (we are only taking if there is no internal earth core)

Thanks

timhoward · Dec 1, 2021

For me it's between no code and C3. The test results show adequate Zs. It would take considerable determined targeted effort to degrade anything to the point that this changed. Certainly not dangerous, so not C1 or C2. Would be better if there was a fly lead. So C3. Or take view that improving it disturbs something that currently works very well so leave the damn thing alone and no code.

Strima · Dec 1, 2021

Continuity readings between gland and MET?

brianmoooore · Dec 1, 2021

I think I would code it C3, just to signify that I've spotted it, if for no other reason.
If the SWA gland is fixed to the same sheet of steel as the earth bar, and there's no sign of significant rust, then I'd be happy with that. I might be less satisfied if the SWA gland is fixed to a bolt on panel, fixed to the main enclosure.

Lucien Nunes · Dec 1, 2021

It's all about the integrity of the connection of the gland to the earth terminal. If it relies on mechanical mounting screws of a gland plate, or the paint / powder coat hasn't been stripped, or there is a likelihood of corrosion, then it's substandard work and deserves a code for that, regardless of any other regs. If it measures OK it can't be a C2 because that applies to an actual break in the earth and this certainly isn't as dangerous, therefore it must be C3.

If none of these deficiencies apply and the gland is evidently solidly connected to a solidly earthed piece of metal, it's no more or less dangerous that if it were earthed by a flylead and gets no code. I would prefer to see non-ferrous contact e.g. with a brass banjo or Piranha nut to avoid corrosion. But mild steel conduit is fine as CPC, and while ideally treated with cold galv spray at the joints, that's not a requirement, so a steel panel under good conditions ought to be similarly OK if not best practice.