Earthing inside a submain panel from main swa incomer

[Guest 004]

Already stated that calcs have been done by 'others' and I'm struggling to see why I need to a adiabatic on a fly lead.

 

[davesparks]

 

[davesparks]

Already stated that calcs have been done by 'others' and I'm struggling to see why I need to a adiabatic on a fly lead.

How else are you going to work out what size it needs to be? It is forming part of the cpc of the circuit so should be calculated the same way.
Your other option is to use the selection table which would have you fitting a 95mm copper flylead.

 

[Leesparkykent]

Already stated that calcs have been done by 'others' and I'm struggling to see why I need to a adiabatic on a fly lead.

So what size are you going to install?

 

[davesparks]

Why has the designer of the installation not specified the method of termination and the size of any flylead required? Or why don't you just enquire as to what it should be? Unless you are accepting liability for this part of the design?

 

[Darkwood]

I dont think he is doubting you are not going to test,I believe what he is saying ,is the test equipment may max out at possibly 20 KA and you may not get an accurate reading

The opposite is what I meant, the resolution of most meters will be to 2 decimal places 0.01, because he is so close to the TX the meter will struggle to verify such a low reading as it will need a minimum level of resistance to settle the reading, as the expected reading is probably going to be at the meters threshhold then it will not find its reading correctly and will generate false readings which will confuse anyone taking them. There are a few options to counter this, buy a nice expensive meter with a higher resolution, or introduce a known resistance into the reading. A simple way would be a local radial socket/spur etc where you can measure the cables R1+R2 giving you a known resistance then you can measure the external impedance from that socket minus the circuits impedance this will then bring your meter back to an accurate reading within its resolution. A simple resistor with high accuracy will also do the trick but not many carry these about as a rule.

 

[Skimpy Wan]

Sorry haven't read the whole post as just walked in the door and the Misses is moaning! Lol

Doesn't GN8 cover what SWA armour can be used as a CPC and which need additional bonding (therfore in parallel).

I'm not sure if I'm allowed to post a link to the page I'm referring to, so please let me know if this is permitted - Mods not us minions! Lol

 

[Skimpy Wan]

If not, maybe I'll see if I can transpose it in a document that is legible for people over the next few days?!

 

[davesparks]

Sorry haven't read the whole post as just walked in the door and the Misses is moaning! Lol

Doesn't GN8 cover what SWA armour can be used as a CPC and which need additional bonding (therfore in parallel).

I'm not sure if I'm allowed to post a link to the page I'm referring to, so please let me know if this is permitted - Mods not us minions! Lol

GN8 does effectively cover it, but it is all there in bs7671 too.
The subject of running bonding conductors alongside an SWA is a completely different matter, and it has presumably already been established that the armour meets any bonding requirements of that there are no bonding requirements

 

[Skimpy Wan]

If not, maybe I'll see if I can transpose it in a document that is legible for people over the next few days as I don't want any repocusions!

 

[davesparks]

You can quote the relevant sections of such a document, or post an image of the appropriate section. But you can't post big chunks of the book like whole pages

 

[Skimpy Wan]

Okay. I'll pay reference to the page / document when I get a chance over the weekend.

 

[Guest 004]

This still will not answer my OP.
FYI the supply cable is FP600, so please post the relevant docs.

 

[Leesparkykent]

This still will not answer my OP.
FYI the supply cable is FP600, so please post the relevant docs.

Your OP asks if you need to have a fly lead from the banjo to the earth bar.....you have had the answer several times and even been quoted reg numbers.

 

[Darkwood]

Reg 543.2.7...where the protective conductor is formed by metal conduit, trunking or ducting or the metal sheath and/or armour of a cable, the earthing terminal of each accessory shall be connected by a separate protective conductor to an earthing terminal incorporated in the associated box or other enclosure.

Not too sure this reg' actually covers the OP's situation, the main switchgear and or distribution equipment isn't classed as an accessory like equipment tapped of each circuit would be IMHO, I did think of this reg' myself but decided it wasn't for this situe'.

 

[Leesparkykent]

Not too sure this reg' actually covers the OP's situation, the main switchgear and or distribution equipment isn't classed as an accessory like equipment tapped of each circuit would be IMHO, I did think of this reg' myself but decided it wasn't for this situe'.

How come you wouldn't class it as the same situation?

 

[Darkwood]

How come you wouldn't class it as the same situation?

Just checking the definitions in the BYB and it seems they have either revised the wording or I'm mixing my regs up as I don't just sit under the BS7671 in my job, so I'll stand corrected on that point, this regulation is applicable although I would argue the case that if you can effectively show you have taked the steps to ensure good solid contact and your not going through gland plates or screwed panelling and the earthing bolt/bar is fixed and grounded to the enclosure directly then you can argue by construction the gland doesn't require a tail.
I think the regulation is too broad in its application but like I said 'If in doubt, tail it out'

 

[Skimpy Wan]

I was referring to GN8 Appendix B (page 161)

 

[Simlec]

I was referring to GN8 Appendix B (page 161)

Would you not use table B2 on the next page? or are you using equipment rated above 70deg?

 

[davesparks]

This still will not answer my OP.
FYI the supply cable is FP600, so please post the relevant docs.

And you didn't think to mention that it's not standard SWA in the OP?

Either way that makes no difference whatsoever to this question.