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.
After requesting further clarity from DNO they said they cannot confirm what earthing system the building is because the transformer was installed by an independant DNO. I contacted the Company who last worked on the Transformer with the independant DNO who said its a TNCS. The Test report for the building however suggests it's a TNS. The building has an independant transformer which feeds no other buildings except this one so its a little wooly me making assumptions as to whether TNS or TNCS. Assuming it is TNS and not TNCS this will make it much simpler and I would be tempted to feed the EVCs from a dedicated D/Board located in the Main LV Switchroom adjacent the TX room. I would feed all the EVCs via individual TP MCBs and ensure the Chargers contain the 16A Type A RCBO within the individual Charging Units. Forget the TT Island and this way the building and the 20 EVCs and the Solar Canopy are all at the same earth potential leaving no room for error. I hadnt realise AMD 1 is released this week so will take a good read when available.
After requesting further clarity from DNO they said they cannot confirm what earthing system the building is because the transformer was installed by an independant DNO. I contacted the Company who last worked on the Transformer with the independant DNO who said its a TNCS. The Test report for the building however suggests it's a TNS. The building has an independant transformer which feeds no other buildings except this one so its a little wooly me making assumptions as to whether TNS or TNCS. Assuming it is TNS and not TNCS this will make it much simpler and I would be tempted to feed the EVCs from a dedicated D/Board located in the Main LV Switchroom adjacent the TX room. I would feed all the EVCs via individual TP MCBs and ensure the Chargers contain the 16A Type A RCBO within the individual Charging Units. Forget the TT Island and this way the building and the 20 EVCs and the Solar Canopy are all at the same earth potential leaving no room for error. I hadnt realise AMD 1 is released this week so will take a good read when available.
