PIR Industrial units, Extended PME.

[skiandy]

Hi,

I have just been asked to do a PIR on some small industrial units where the PME supply is extended to units in outbuildings. The main installation was completed 20 years ago when there was a 11kv transformer. Since then the DNO changed the supply to PME. Some of the units have earth rods but they are not configured as TT Systems, because the supply form the meter room is in SWA terminated in metal distrubtion boards. Ze on all the distrubtion boards checks out ok for TN-C-S but my understanding is that the PME supply should not be extended to the out buildings. Any recomdations/ideas?

Andy

 

[EasyFox]

I'd say it's not a problem so long as the normal things are in place at the outbuildings such as equipotential bonding. you'll need to use the adibiatic to make sure the mec to outbuildings meets the csa requirements of 7671 though.

 

[weyboy]

the outbuildings should not be connected to the PME supply of main DB and should have their own TT earth supply

 

[skiandy]

The outbuildings are suitable for PME as they are build from stone, there are no other services run in; no gas and water is in poly.

The CSA of the SWA is enough to support the PME bonding as well as the CPC. I just can't see the point of the earth rod being sunk. As it's a PIR I can't really justifiy the recommendation that the installation should be split up i.e. terminate the SWA in a plastic inclosure and then run tails to the distrubution board....

 

[Shakey]

The outbuildings are suitable for PME as they are build from stone, there are no other services run in; no gas and water is in poly.

The CSA of the SWA is enough to support the PME bonding as well as the CPC. I just can't see the point of the earth rod being sunk. As it's a PIR I can't really justifiy the recommendation that the installation should be split up i.e. terminate the SWA in a plastic inclosure and then run tails to the distrubution board....

well using spikes with PME is quite acceptable, remember the ME bit is Multiple Earthing. The regs actually say ' an electrode may be required at or near the consumers installation' or words to that effect