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I just noticed a really interesting addition to the Canadian Electrical Code in the 2021 edition:
notwithstanding Items c) and d), the sum of the ampere rating of the overcurrent devices shall be permitted to exceed the rating of the busbar or conductor where means are provided to limit the input and output current of the interconnected systems to ensure the busbar or conductor cannot be overloaded
In the past, I wondered why a busbar can't be fed from both ends to 100% of its capacity. For example, if the main service breaker is 100A for a 100A busbar, I can put 2 40A breakers for 7.6 kW inverters at the opposite end of the bus, and no part of the bus can ever carry more than 100A. However the 2018 CEC would limit the PV breaker to 25A (25% of 100A).
The "means" to ensure the busbar cannot be overloaded would be the physical placement of the PV system breakers at the opposite end of the bus from the main service breaker.
notwithstanding Items c) and d), the sum of the ampere rating of the overcurrent devices shall be permitted to exceed the rating of the busbar or conductor where means are provided to limit the input and output current of the interconnected systems to ensure the busbar or conductor cannot be overloaded
In the past, I wondered why a busbar can't be fed from both ends to 100% of its capacity. For example, if the main service breaker is 100A for a 100A busbar, I can put 2 40A breakers for 7.6 kW inverters at the opposite end of the bus, and no part of the bus can ever carry more than 100A. However the 2018 CEC would limit the PV breaker to 25A (25% of 100A).
The "means" to ensure the busbar cannot be overloaded would be the physical placement of the PV system breakers at the opposite end of the bus from the main service breaker.
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