- Thread starter bluestar
- Start date

If you're nameplate total inverter output is 39A, then your backfeed calc is 39A*1.25=48.75A. So you are not compliant.

One solution might be to do a load calculation and downsize the main breaker to 175A. Then 240-175=65 and you have enough 'headroom.'

One example where the 2014 change in this rule would help you, is given a 600A main panelboard with a 600A main breaker.

If you're nameplate total inverter output is 39A, then your backfeed calc is 39A*1.25=48.75A. So you are not compliant.

One solution might be to do a load calculation and downsize the main breaker to 175A. Then 240-175=65 and you have enough 'headroom.'

In 2011 rules, you'd be limited to a 110A interconnection breaker (unless you have a rare situation where you can find and fit a 120A breaker), and this would mean a maximum total inverter output current of 88A.

In 2014+ rules, you'd be limited to a 120A as your calculation of 125% of total inverter output current. This would mean you can have up to 96A of total inverter output current, interconnected to this same panelboard.

Probably 225. If it can take a 225A breaker then the busbar must be rated for that.question if I may, as I am trying to understand... the last panel I dealt with in Jamaica was a 200 amp main breaker, but the box itself was labelled do not use more than 225 amps breaker... so which would be used for the above calculations, the 225 or the 200?

Yes.Like a 125 bus with a 100 amp main breaker?

More or less, yes. Usually I simply see a label that says 'Mains Rating xxxA', and that's what I go by.If panel says no more than x breaker then is that the rating to use? Then see if you can drop the main breaker enough to allow the back feed?