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I’ve seen debate in the past on here about whether to earth both ends of SWA at the glands even when using 3 core with a core as the cpc. My question is:
If I gland the load end and earth the banjo there, then gland the supply end but run the 3 cores straight through the building skin so there are no terminations (obviously us Using the SWA inner sheath and mounted in a Wiska box), should I then run a fly lead from that gland through the building to the inside fcu?
As it stands, I have good r1+r2 readings and a good Zs (0.59) my earth fault path runs along the SWA armour to the earthed gland and then returns back via the central cpc cable.
To earth the other gland I would either need to make a larger hole in the building to make room for a fly lead, or cut the cable at the junction box so can add an earth - the way I see it is that I would then create an unnecessary break and additional joints in the cable.
Anyone got any views on this? Thanks
 
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Personally I would earth it at supply end. How far is the armoured running through the building in its bedding ? What mechanical protection are you providing from the fcu to the exit of the building/ wiska box ?
 
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  • #3
Cable runs directly from the back of the fcu through the wall to the wiska box outside -does it need further mechanical protection?
Should I have drilled a larger diameter hole, pushed conduit through and threaded the 3 core and earth fly lead through this maybe?
I guess I’m answering my own question!! Just curious as to how others do it.
I have previously ran t&e from the fcu to wiska and terminated in the wiska but thought I’d do something that reduced the number of terminations..
 
Cable runs directly from the back of the fcu through the wall to the wiska box outside -does it need further mechanical protection?
Should I have drilled a larger diameter hole, pushed conduit through and threaded the 3 core and earth fly lead through this maybe?
I guess I’m answering my own question!! Just curious as to how others do it.
I have previously ran t&e from the fcu to wiska and terminated in the wiska but thought I’d do something that reduced the number of terminations..
I put an off cut of plastic conduit in normally to go through wall. I thought you had a fairly long run. Depending on size of armoured you should be able to fit a suitable cpc through to bolt to banjo. Failing that it’s ok to earth other end, but I always tend to earth origin end as things get altered or added to
 
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  • #6
Wot about a Piranha Earth Lock Nut or is that not the issue?
Not an issue - I have the banjo nicely in place, I have crimps and a nicely prepared fly lead - just nowhere to connect its other end!!
Think I’ll do a revisit - drill out a larger hole, put some conduit through and terminate the fly at the fcu earth terminal for peace of mind....
 
I would earth it both ends, just me personally.
Yea so would I,been extending Swa”s ,that have been in service for decades,like 185 mm 4 core 3p & N,no earth cables,using sheath for cpc,looking @ some tables this may t prove to be ok,realistically a 95mm should have been installed with it.
Coding?
 

davesparks

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Yea so would I,been extending Swa”s ,that have been in service for decades,like 185 mm 4 core 3p & N,no earth cables,using sheath for cpc,looking @ some tables this may t prove to be ok,realistically a 95mm should have been installed with it.
Coding?
Tables won't tell you the answer, you need to calculate the required steel CSA using the adiabatic equation before deciding whether it is suitable or not.
 

davesparks

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Not an issue - I have the banjo nicely in place, I have crimps and a nicely prepared fly lead - just nowhere to connect its other end!!
Think I’ll do a revisit - drill out a larger hole, put some conduit through and terminate the fly at the fcu earth terminal for peace of mind....
How did you get the banjo properly fitted in a wiska box?
I'd have made it off into a galv terminal box personally, then it's got an earth terminal there ready to go.
 
Tables won't tell you the answer, you need to calculate the required steel CSA using the adiabatic equation before deciding whether it is suitable or not.
Thanks there are tables @ there that have calculated the swa’s, & apparently the 185mm,using the sheath is ok for a cpc.
 

davesparks

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Thanks there are tables @ there that have calculated the swa’s, & apparently the 185mm,using the sheath is ok for a cpc.
Tables at where?
Unless you mean someone has produced a table specific to that site, from that particular origin etc then I don't see how that's possible.
The input data to the adiabatic equation is going to change with each cable run,
 
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  • #15
How did you get the banjo properly fitted in a wiska box?
I'd have made it off into a galv terminal box personally, then it's got an earth terminal there ready to go.
It’s outside - the banjo bends up - never had a problem fitting a banjo on these ones
 
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