A daft question, or not....!

[polo1]

Three core SWA installed as a new circuit on a TNS supply. Both ends of the SWA are earthed.
Would you/ is it acceptable to include the armour in the R1+R2 calculation (ie in parallel with the core being used as cpc) or should measurement simply be between cores?

 

[ipf]

Think about it. What do you think?

 

[polo1]

I know what I think.....I want to know what YOU think ;>)

 

[ipf]

Ah... but I know. It's what you think that I also want to know. Do you want it on a plate.
Tell us what you think....and why!

 

[telectrix]

Ah... but I know. It's what you think that I also want to know. Do you want it on a plate.
Tell us what you think....and why!

typical Lancashire. get round to turning on Blackpool lights come April.

 

[polo1]

Nope! I know too. It was the very fact that the issue came up on site the other day, I’m keen to see how others respond to the question.
Not meaning to be awkward ( well not a lot anyway!).

 

[ipf]

typical Lancashire. get round to turning on Blackpool lights come April.

Got to do my prep, mate.

 

[telectrix]

if a dog wags it's tail and it's arse at the same time, is it the tail that wags or the arse, or both? or does the tail wag the dog?

 

[Deleted member 26818]

No you would not include the armour, it’s an exposed conductive-part.
Just the same as you would not include metal conduit, trunking, cable tray, etc.

 

[telectrix]

No you would not include the armour, it’s an exposed conductive-part.
Just the same as you would not include metal conduit, trunking, cable tray, etc.

but whatif the armour is the sole cpc?

 

[ipf]

No you would not include the armour, it’s an exposed conductive-part.
Just the same as you would not include metal conduit, trunking, cable tray, etc.

Who's known cable tray used as a cpc?

 

[Deleted member 26818]

but whatif the armour is the sole cpc?

If the armour is used as the CPC, then you will have to measure R2 with the armour disconnected from any earthed conductive-parts.

 

[Deleted member 26818]

Who's known cable tray used as a cpc?

Tray, ladder rack, basket (not so much basket) are often earthed at each end of a run and would be a parallel Earth path.

 

[ipf]

Tray, ladder rack, basket (not so much basket) are often earthed at each end of a run and would be a parallel Earth path.

Get real and don't sidestep.

 

[Deleted member 26818]

Get real and don't sidestep.

Sorry you don’t think I am being real.
Sidestep what?
I think what you should really be asking, is what to do if conduit or trunking is used as a CPC.

 

[Leesparkykent]

No you would not include the armour, it’s an exposed conductive-part.
Just the same as you would not include metal conduit, trunking, cable tray, etc.

The armour is not an exposed conductive part. It's conductive but not exposed as it's covered by a sheath.

 

[Deleted member 26818]

The armour is not an exposed conductive part. It's conductive but not exposed as it's covered by a sheath.

That’s ok then.
I guess neither are back boxes buried in walls?

 

[Leesparkykent]

That’s ok then.

what's ok?

 

[Simonslimline]

The armour is not an exposed conductive part. It's conductive but not exposed as it's covered by a sheath.

Guidance not 8 refers to the armouring as being an exposed conductive part.

Something to do with the gland?

 

[Leesparkykent]

Guidance not 8 refers to the armouring as being an exposed conductive part.

Something to do with the gland?

Yeah if a brass gland is used then the brass gland is an exposed conductive part unless covered by a shroud. If it's covered by a shroud then it's just a conductive part.