Inverter Tie In Canadian Code

B

bellington

Senior Member
Location
Hahira, GA
Occupation
Consultant
Good afternoon gentlemen. In the Bahamas, under Canadian Electrical Code, apparently, the approved method of inverter tie in is with Polaris lugs. My logic strongly resists cutting (2) brand new 4/0 cable to SPLICE in inverter feed. Then, I tried to apply my logic to NEC codes for buss bars so I could tie in through breakers in the panel. Then, I get to the Canadian Code and they don't seem to care about feeders. So, they simply slice in the inverters before the breaker panel.

Is there someone who can help apply some logic to the reason for demanding such an oversized buss when the load demand is not changed by the source of energy supplied to the load? And, why that rule overrides the logic of fewer connections and absolutely no SPLICE in a cabinet?

Please tell me there is another option than buying and 800 amp panel for a 600 demand load service, if I want to connect to through breakers.

Thanks,

Byron
 
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I can't speak to the Canadian code. We use Polaris lugs all the time to reconnect 100-200A feeders when we are putting existing subpanels on battery backup. Although I understand your reservations, it's an accepted method. One thing I like to do for taps like your describing is get a double-entry Polaris type connector that is a couple sizes too large, and slip it over the conductor to be spliced so that you are not actually cutting it; that might meet your preference.

Regarding the NEC bus sizing rules, the idea is that if the sum of utility overcurrent protection and inverter output exceed the busbar, then the utility overcurrent protection is theoretically defeated. But I completely agree that the limits are way more conservative than they likely need to be. Note that 705.12(B)(3)(3) can qualify a lower rated busbar in some situations.
 
jaggedben said:
I can't speak to the Canadian code. We use Polaris lugs all the time to reconnect 100-200A feeders when we are putting existing subpanels on battery backup. Although I understand your reservations, it's an accepted method. One thing I like to do for taps like your describing is get a double-entry Polaris type connector that is a couple sizes too large, and slip it over the conductor to be spliced so that you are not actually cutting it; that might meet your preference.

Regarding the NEC bus sizing rules, the idea is that if the sum of utility overcurrent protection and inverter output exceed the busbar, then the utility overcurrent protection is theoretically defeated. But I completely agree that the limits are way more conservative than they likely need to be. Note that 705.12(B)(3)(3) can qualify a lower rated busbar in some situations.
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When you say slip the Polaris connector "over," do you mean remove insulation for the Polaris and slip it over the insulation, then tighten? If so, you may have solved my main issue.
 
bellington said:
When you say slip the Polaris connector "over," do you mean remove insulation for the Polaris and slip it over the insulation, then tighten?
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Yes, you get a connector where the minimum conductor size is small enough for the bare "run" conductor on your splice, and maximum conductor size exceeds the "run" conductor diameter including its insulation. Then you just strip a short segment of insulation from the part of the "run" conductor where you want your connector to end up. The connector will fit over the remaining insulation between that location and the end of the conductor.

Cheers, Wayne
 
What Wayne said. You do have to be able to do this in or near an enclosure where you can take the existing conductors off their terminations and then re-terminate them. Like, in the panel they land in. Can't easily do it in the middle of a run.
 
Thank you. Good to hear from all of you again. I think I can live with this method, especially when I'm doing 60 amps from an inverter into a 250 MCM cable.

Thanks!
 
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