main breaker

[jociha]

I am up grading a service 208/120 3p, my total load is about 560a. Can i use a 600amp main breaker and panel or do i risk tripping a breaker loaded more than 80%. Should i specify a 100% duty breaker than use a 600a panel and breaker or just install a 800a system? john

 

[hurk27]

Re: main breaker

I would go as far as the money would allow as if your upgrading now and only leave 40 amps head room you will be upgrading in a very short time. New equipment is developed all the time and is added and not to leave some head room for future expansion will be a bigger cost later on. sounds like you need to go 800 amps to even start. Maybe more depending upon what type of facility this is.

This is only my opinion not a NEC requirement.

 

[kiloamp7]

Re: main breaker

Depends on a lot of things, such as: what are these loads, which loads are continuous in nature, what type occupancy or facility is this,where is the money coming from, etc.

Important to read NEC definition of continuous load closely. "The maximum current- - -". Usually this is a load like the general lighting in most commercial/industrial occupancies.

There are some loads that are actually in operation for 3 hours or more but are not continuously drawing their maximum current.

If your 560A figure takes into account all the Art.220 rules, then a standard 600A molded case bkr. is probably okay. But remember their is little room for any future loads though.

I believe the "somebodies" rules require a plain Jane 600A molded case bkr. to be able to carry 80% of its rating (480A) continuously. There are also 700A bkrs.