Exporting PME

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Traineeboy

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What is your view on exporting PME earthing ? 
 

if you have a PME system that also serves an outbuilding then from that outbuilding you want to power another outbuilding ( that will have a metal structure) is it better to convert the 2nd outbuilding to a TT system ? 

 
How can you export a PME system? The earthing arrangement stops and the suppliers head.

If you needed to supply an external building with services or components that require bonding then you could TT them to save on cable but this in itself has its own inherent problems.

 
How can you export a PME system? The earthing arrangement stops and the suppliers head.

If you needed to supply an external building with services or components that require bonding then you could TT them to save on cable but this in itself has its own inherent problems.
Ok I have been told then when an outbuilding is more than 20 meters away from a house you shouldn’t use the suppliers earth if a PME.  You would just run 2 core swa to the outbuilding then use an earth rod to provide your own earth. 

 
It's a whole can of worms this, and getting sparks to agree on whether or not an outbuiding, hot tub or anything else being powered externally to the main supplied building should use the suppliers PME or be TT'd is akin to trying to solve the middle east troubles. 

There are pros and cons to both, it's very much dependant on the site and it rears its head whenever a outbuilding, hot tub or EV charger is mentioned. Banging earth rods in at will can introduce its own issues, particularly where PME supplies are used. Some DNOs allow you to export the PME others don't, that's if you contact them about it at all. 

Have a look for John Ward on youtube, he does a video on earthing outbuidings. There is also a good one on EV charging installs and the dangers of TN-C-S sytems by him too. 

 
It's a whole can of worms this, and getting sparks to agree on whether or not an outbuiding, hot tub or anything else being powered externally to the main supplied building should use the suppliers PME or be TT'd is akin to trying to solve the middle east troubles. 

There are pros and cons to both, it's very much dependant on the site and it rears its head whenever a outbuilding, hot tub or EV charger is mentioned. Banging earth rods in at will can introduce its own issues, particularly where PME supplies are used. Some DNOs allow you to export the PME others don't, that's if you contact them about it at all. 

Have a look for John Ward on youtube, he does a video on earthing outbuidings. There is also a good one on EV charging installs and the dangers of TN-C-S sytems by him too. 
great cheers mate I’ll take a look. 

 
It's a whole can of worms this, and getting sparks to agree on whether or not an outbuiding, hot tub or anything else being powered externally to the main supplied building should use the suppliers PME or be TT'd is akin to trying to solve the middle east troubles. 


I think it would be easier to solve the Middle East crisis

on the subject of TT the outbuilding, and the obsession for metal fuseboard You need also ensure the SWA isn’t connected to the fuseboard at both ends of the cable too

 
I think it would be easier to solve the Middle East crisis

on the subject of TT the outbuilding, and the obsession for metal fuseboard You need also ensure the SWA isn’t connected to the fuseboard at both ends of the cable too
yes got ya. SWA earthed at supply then safely isolated at the other end. Also need to make sure that no exposed conductive parts connected to the house don’t enter the outbuilding. 

 
I gather that if you wanted an outbuilding via a TN-S system you won’t have the same issue that you would have with a TN-C-S (PME) ? 

 
I gather that if you wanted an outbuilding via a TN-S system you won’t have the same issue that you would have with a TN-C-S (PME) ? 
Think about the different earthing arrangements and what would happen if the supply neutral was cut.

 
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