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Discuss Working on electrics with 2 supplies. in the Electrical Forum area at ElectriciansForums.net
it's not just PV you need to worry about, UPs and Standby sets need isolation prior to working on, many organisations with multiple Supplies operate an AP, LV, PtoW system to allow for safe workingI have little knowledge of PV.
When working on circuits supplied by a domestic CU, is it fine to just have the main switch off in the CU or should you be isolating the PV as well?
The stickers all over the CU's in this example all say to disconnect both supplies.
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I have little knowledge of PV.
When working on circuits supplied by a domestic CU, is it fine to just have the main switch off in the CU or should you be isolating the PV as well?
The stickers all over the CU's in this example all say to disconnect both supplies.
View attachment 49460 View attachment 49461 View attachment 49462 View attachment 49463
If this did happen then if I have the MCB switched off on the circuit I am working on, is there any way this circuit could become live? I can't see how? This isn't a reason not to isolate both supplies it's just for me to understand it better.All off please !
Otherwise the inverter may kick in and liven up the CU ...
I thought all grid-tied inverters,had to shut down,on the loss of supply,to protect supply personnel,on an outage...
I believe you're correct.
However, for the sake of flicking a switch, would you risk it?
Also see post 4The inverter itself should shut down so that it does not backfeed AC to the DB when the mains is off, although as mentioned one should not rely on that. Because its output neutral is not referenced to earth (until it is tied to the DNO supply) the SP MCB does not make it 100% safe if it did start up, as a difference in leakage could make the N more live than the L.
But, the main point of the '2 supplies' stickers around the inverter is to remind that with the AC off, the DC from the panels is still live unless it's dark. So before working on the inverter, both the DC and AC sides need to be isolated.
Reply to Working on electrics with 2 supplies. in the Electrical Forum area at ElectriciansForums.net
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