KeithR Posted March 28, 2023 Share Posted March 28, 2023 Hi all, My Electrician has wired my DB board as shown in the simplified schematic below. I note the following: The grid-feed to the change-over is taken from the output side of Beaker-A. If there's a need to make the Inverter DB safe, this would need Breaker-A to be off (and the Inverter) which means there is no supply to essential loads during this time. Shouldn't the grid-feed to the change-over be tied in before Breaker-A? For the return to the Main DB there is an MCB on the inverter side (#D), then another in the Main DB (#B), and then the change-over. Is this all necessary? The cabling is protected by Breaker-D and the change-over is an isolator. Taking out Breaker-B opens up two DIN rail slots which would help me. Any thoughts? Thanks Quote Link to comment Share on other sites More sharing options...
BritishRacingGreen Posted March 28, 2023 Share Posted March 28, 2023 (edited) 30 minutes ago, KeithR said: Hi all, My Electrician has wired my DB board as shown in the simplified schematic below. I note the following: The grid-feed to the change-over is taken from the output side of Beaker-A. If there's a need to make the Inverter DB safe, this would need Breaker-A to be off (and the Inverter) which means there is no supply to essential loads during this time. Shouldn't the grid-feed to the change-over be tied in before Breaker-A? For the return to the Main DB there is an MCB on the inverter side (#D), then another in the Main DB (#B), and then the change-over. Is this all necessary? The cabling is protected by Breaker-D and the change-over is an isolator. Taking out Breaker-B opens up two DIN rail slots which would help me. Any thoughts? Thanks I am in line with your reasoning on both counts. But we need to assume that wire/cable thickness as depicted in your drawing are all the same. 1 technically feeding the grid bypass from the output of A serves no purpose and its confusing because A is labelled INVERTER. Breaker A serves the purpose of protecting and isolating the inverter grid feed as it leaves the main box. Breaker C is only there to switch off the inverter in reaching distance from the inverter. Ideally this is an isolator, need not be a circuit breaker. 2 Breaker D is important as you pointed out and must be a circuit breaker to protect the load cable back to the main box. Breaker B technically serves no purpose at all. Other opinions of course are welcome and important. Edited March 28, 2023 by BritishRacingGreen Modina and root 2 Quote Link to comment Share on other sites More sharing options...
KeithR Posted March 28, 2023 Author Share Posted March 28, 2023 Thanks, and yes, the cables are the same. Quote Link to comment Share on other sites More sharing options...
BritishRacingGreen Posted March 28, 2023 Share Posted March 28, 2023 31 minutes ago, BritishRacingGreen said: I am in line with your reasoning on both counts. But we need to assume that wire/cable thickness as depicted in your drawing are all the same. 1 technically feeding the grid bypass from the output of A serves no purpose and its confusing because A is labelled INVERTER. Breaker A serves the purpose of protecting and isolating the inverter grid feed as it leaves the main box. Breaker C is only there to switch off the inverter in reaching distance from the inverter. Ideally this is an isolator, need not be a circuit breaker. 2 Breaker D is important as you pointed out and must be a circuit breaker to protect the load cable back to the main box. Breaker B technically serves no purpose at all. Other opinions of course are welcome and important. There might be an argument that Breaker B is a convenient point to switch off the incoming inverter output to rest of the main db. I am not 100% sure that this is a COC requirement though. Quote Link to comment Share on other sites More sharing options...
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