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Topic Title: Earthing Conductor Installation / High Zs
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Created On: 21 January 2019 08:53 AM
Status: Read Only
Linear : Threading : Single : Branch
 Earthing Conductor Installation / High Zs   - PWatts - 21 January 2019 08:53 AM  
 Earthing Conductor Installation / High Zs   - AJJewsbury - 21 January 2019 12:20 PM  
 Earthing Conductor Installation / High Zs   - gkenyon - 21 January 2019 01:56 PM  
 Earthing Conductor Installation / High Zs   - chrispearson - 21 January 2019 01:59 PM  
 Earthing Conductor Installation / High Zs   - OMS - 21 January 2019 02:35 PM  
 Earthing Conductor Installation / High Zs   - PWatts - 21 January 2019 03:56 PM  
 Earthing Conductor Installation / High Zs   - Alcomax - 21 January 2019 04:21 PM  
 Earthing Conductor Installation / High Zs   - PWatts - 21 January 2019 04:24 PM  
 Earthing Conductor Installation / High Zs   - Alcomax - 21 January 2019 05:37 PM  
 Earthing Conductor Installation / High Zs   - chrispearson - 22 January 2019 09:48 AM  
 Earthing Conductor Installation / High Zs   - AJJewsbury - 22 January 2019 11:01 AM  
 Earthing Conductor Installation / High Zs   - mapj1 - 22 January 2019 11:06 AM  
 Earthing Conductor Installation / High Zs   - John Peckham - 22 January 2019 11:06 AM  
 Earthing Conductor Installation / High Zs   - PWatts - 22 January 2019 04:21 PM  
 Earthing Conductor Installation / High Zs   - mapj1 - 22 January 2019 04:27 PM  
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 22 January 2019 11:06 AM
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mapj1

Posts: 12039
Joined: 22 July 2004

IF the resistance of the earth path is over 2 ohms, what is the resistance of the cores and the IR results looking like ? If water has got into a joint, then you could be sitting on a bigger problem to come, where at the most inconvenient moment possible it goes snap crackle and pop.. As others have said, the equivlalent of an earth fault relay to provide RCD-like protection will get you back within the regs, or as you propose an external CPC. However, neither is cheap, and both are something of a sticking plaster.
IF you wanted to identify the losses, then a low voltage supply and a few tens of amps will make the loss appear as a hot spot.
If you are dismantling to add banjos or pirahnas to the glands, then while you have it in bits, note that the most likely place for resistance in an undamaged cable is where the steel wires meet the brass glands, if they have not been properly combed out and seated flat before tightening, then only one or two strands are really pinched and connected to the gland, and the rest may look ok but are free to flap about and not make contact.
If you have access in the dry, and can 'vampire' a meter contact to the armour (and then cover the damage with self amalgamating tape) you can verify the steel armour to brass resistance directly. It might be all at one end.

Edit and of course while doing that verify the resistance from the brass gland to the rest of the metal it is supposed to connect to as well.

-------------------------
regards Mike


Edited: 22 January 2019 at 11:14 AM by mapj1
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