6-handle rule

Brent
Brent Solar Expert Posts: 64 ✭✭✭✭
in PV Installers Forum - NEC, Wiring, Installation #1
I remember reading somewhere that each handle of a tandem dual breaker [like a typical 240v 40A panel breaker] counts when applying the 6 handle rule. If so then only 3 breakers would be allowed in a panel if there is no main service disconnect.

Any comments would be appreciated.

Brent
· Share on Twitter

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,639 admin
    #2
    Re: 6-handle rule

    I Googled and found a number of articles, such as this one:

    http://solarprofessional.com/articles/design-installation/maximum-number-of-disconnects

    I think I am a little confused--This is not an area that I have much knowledge... But this would appear to a, for example, a service to an apartment building with 6 meter+main panels+1 disconnect set per panel) connected to that single service.

    Are you doing something like that?

    Otherwise, would not your 120/240 panel have an upstream single disconnect/meter somewhere?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter
  • Brent
    Brent Solar Expert Posts: 64 ✭✭✭✭
    #3
    Re: 6-handle rule

    This is actually for a PV installation at a residence. The existing service panel [old] is rated at 125A with 4 240V breakers and no main breaker. The combined amperage of the 4 breakers is 200A. One of the breakers [60A] runs to a new 125A subpanel which has 30A of PV backfeed breakers. I am trying to determine if the 6-handle rule applies. Code does not require adding breakers but I am concerned about a potential overload the 125 bus. The panel probably once had the usual note on the instructions limiting the use of the panel [as a service panel] to no more than six breakers and excludes breakers for lighting and appliances.

    Brent
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: 6-handle rule

    I don't know what the AHJ there would say, but I know what would happen here: new service panel because the electrical system is being altered and the existing install no longer meets code.

    From what I see the bars in the main panel (no main breaker) rated at 125 Amps could be subject to overload as any one of the 240 VAC breakers is 200 Amps and an additional 30 Amps can come from PV. Yes/no? Biggest problem is not with the PV but with having 200 Amp breakers on 125 Amp bars. That's already over the 120% rule.

    Or perhaps I'm misunderstanding the design.
    · Share on Twitter
  • Brent
    Brent Solar Expert Posts: 64 ✭✭✭✭
    #5
    Re: 6-handle rule

    That's what I thought too. What I might suggest to the installer is to put in a 125A breaker at the top of the panel and backfeed the breaker with the service conductors. I think that would solve the issue since it now limits the current.

    Brent
    · Share on Twitter

Categories