So the armor is being protected by the TT arrangement? as you tried achieving selectivity from the PME DB fed by an MCB? What Fault protection is on the SWA? If someone puts a spade through that SWA with a resistance to earth reading of 51ohms you will get 4.5amps of fault current , nothing will trip!
This is why if at all possible i avoid turning outbuildings fed with SWA into a TT system, you rarely will get a low enough Ze to give you a good fault current. If you are going to put an earth rod in, i would use it to supplement the PME not replace it.
Usually " divorce". the earth conductor in an adaptable PVC box close coupled to the metal unit...sealed...so is never introduced into the c u ...only live & neutral in bedding material passing through into the c.u....
Surely if you continue the CPCs through that (Henson?) box you are not isolating the earths at all? The armoring will be connected to CPCs at the house PME end? The CPCs in the shed will be ultimately connected to the PME earth?
I certainly wouldn’t separate the armouring from the PME at the house end as you’ve now brought 2 different earth potentials into the equipotential zone of the house??? If I was divorcing the earth to create a TT I would do this at the outbuilding end.
Was there any need for the earth rod at all in that shed mate? No extraneous conductive parts and constructed of wood? I would have used the PME personally also was that 51 ohms not 0.51 ohms, great video!!
He said in the video he was going to take the armour into a plastic box at the house end as he couldn’t get a plastic CU for the shed. Not sure why a earth rod for the shed unless there are extraneous conductive parts coming in, however the client may have said they want to bring something like plumbing in so there could be something in mind so maybe forward planning. The again I am a DIY bodger so what would I know.
@@davideyres955is he trying to say that the swa cpc is protected by the tt rod, if so would it not need rcd protection at the house end to protect the swa cable
@@jamievaughan6431 That does not explain the problem, 411.4.2 of the 18th Edition, recommends an additional connection to earth by means of an earth electrode.
No short circuit protection on the swa coming into db between the casing of the db and the armouring .... That live shoule be doible insulated and i would disconnect the swa from the tt .. that plastic board they didnt have would have solved it or just the pme ..
So the armor is being protected by the TT arrangement? as you tried achieving selectivity from the PME DB fed by an MCB?
What Fault protection is on the SWA?
If someone puts a spade through that SWA with a resistance to earth reading of 51ohms you will get 4.5amps of fault current , nothing will trip!
This is why if at all possible i avoid turning outbuildings fed with SWA into a TT system, you rarely will get a low enough Ze to give you a good fault current. If you are going to put an earth rod in, i would use it to supplement the PME not replace it.
Usually " divorce". the earth conductor in an adaptable PVC box close coupled to the metal unit...sealed...so is never introduced into the c u ...only live & neutral in bedding material passing through into the c.u....
Yes ,earth the armouring at main consumer unit and isolate armouring at shed unit……..it’s a must
Mike thought about a hammer sds for the earth rod driving
Surely if you continue the CPCs through that (Henson?) box you are not isolating the earths at all? The armoring will be connected to CPCs at the house PME end? The CPCs in the shed will be ultimately connected to the PME earth?
I certainly wouldn’t separate the armouring from the PME at the house end as you’ve now brought 2 different earth potentials into the equipotential zone of the house??? If I was divorcing the earth to create a TT I would do this at the outbuilding end.
Why did you have to put the earth rods in and did not chose to utilise the earth terminal on the house consumer unit? Were you worried about the Zs?
The Zs from the house PME is the least of the concerns with a local Ze of 51 ohms! lol
Was there any need for the earth rod at all in that shed mate? No extraneous conductive parts and constructed of wood?
I would have used the PME personally also was that 51 ohms not 0.51 ohms, great video!!
Thanks for the video Mike - don't quite understand why you need TT earthing. No extraneous conductive parts? But you know more than I do...
PME Supply
@JIBS. And??? There's no need if there's no extraneous parts out there total waste of time just to get a crap earth reading
@@JIBS. Search John Ward Earthing Systems for Outbuildings
So the accessories in the shed are protected by the exported PME R2 conductor in the swa and the rod is connected to the armour at the shed end?🤔
He said in the video he was going to take the armour into a plastic box at the house end as he couldn’t get a plastic CU for the shed. Not sure why a earth rod for the shed unless there are extraneous conductive parts coming in, however the client may have said they want to bring something like plumbing in so there could be something in mind so maybe forward planning. The again I am a DIY bodger so what would I know.
@@davideyres955is he trying to say that the swa cpc is protected by the tt rod, if so would it not need rcd protection at the house end to protect the swa cable
I'm confused, can someone explain why the earth electrode can't be connected back to the consumer unit, please?
Pme
@@jamievaughan6431 That does not explain the problem, 411.4.2 of the 18th Edition, recommends an additional connection to earth by means of an earth electrode.
No short circuit protection on the swa coming into db between the casing of the db and the armouring .... That live shoule be doible insulated and i would disconnect the swa from the tt .. that plastic board they didnt have would have solved it or just the pme ..
Are you sure you got 0.51?
No need for an Earth rod for that type of installation
All that time wasted on earthing and there was no reason it couldn’t just be connected to PME….