A 4 storey office block with it's own transformer on a TNCS system requires 20 EVC points located in a rear goods yard. Each are 11kw 3 phase so 16A TP apiece via 16A Type A RCBOs. Each EVC will be independanly spiked using either a traditional earth spike or a Condudisc to make them TT. All SWAs will terminate at an adaptable box in LV Switchroom mounted below D/Board thus keeping all EVC earths seperate to that of the TNCS. The plan is to install a metal construction solar panel canopy over the 20 parking bays. Presumably this will need earthing but to which system? The legs of the canopy are metal and may fall within 2m of a number of EVCs. I'm guessing bond them to the local TT Charging point? The other issue is the solar on the canopy roof which is importing back into the buildings LV TNCS System currently serving the building and the question is - will this need earth seperation and to what system. Any feedback is greatly appreciated.
Each are 11kw 3 phase so 16A TP apiece via 16A Type A RCBOs. Each EVC will be independanly spiked using either a traditional earth spike or a Condudisc to make them TT. All SWAs will terminate at an adaptable box in LV Switchroom mounted below D/Board thus keeping all EVC earths seperate to that of the TNCS. The plan is to install a metal construction solar panel canopy over the 20 parking bays. Presumably this will need earthing but to which system? The legs of the canopy are metal and may fall within 2m of a number of EVCs. I'm guessing bond them to the local TT Charging point?
Good point from JP - is the supply isn't PME then you can keep the TN earthing system and everything is much simpler.
If you do have to create a TT island, I can't help thinking it would be a lot simpler just to have one TT earthing arrangement for all the EVSEs (and PV as well) - rather than one each and running into problems where they're within reach of each other.
I might even be tempted to keep the SWA on the TN system - gapping it at the charge points - then as JP suggests you (probably) don't need an extra RCD on the supply.
You might want to wait until this Monday when the IET will make available the 18th Edition AMD 1, free to view on line £5 to download and have a good read before starting your design.
Very good point - I know there were some fairly radical suggestions made to overcome some of the 'within reach' problems during the DPC process - it'll be very interesting to see if any made they way into the final version.
Each are 11kw 3 phase so 16A TP apiece via 16A Type A RCBOs. Each EVC will be independanly spiked using either a traditional earth spike or a Condudisc to make them TT. All SWAs will terminate at an adaptable box in LV Switchroom mounted below D/Board thus keeping all EVC earths seperate to that of the TNCS. The plan is to install a metal construction solar panel canopy over the 20 parking bays. Presumably this will need earthing but to which system? The legs of the canopy are metal and may fall within 2m of a number of EVCs. I'm guessing bond them to the local TT Charging point?
Good point from JP - is the supply isn't PME then you can keep the TN earthing system and everything is much simpler.
If you do have to create a TT island, I can't help thinking it would be a lot simpler just to have one TT earthing arrangement for all the EVSEs (and PV as well) - rather than one each and running into problems where they're within reach of each other.
I might even be tempted to keep the SWA on the TN system - gapping it at the charge points - then as JP suggests you (probably) don't need an extra RCD on the supply.
You might want to wait until this Monday when the IET will make available the 18th Edition AMD 1, free to view on line £5 to download and have a good read before starting your design.
Very good point - I know there were some fairly radical suggestions made to overcome some of the 'within reach' problems during the DPC process - it'll be very interesting to see if any made they way into the final version.
