Sub Panels

[Alectric]

When you run a second sub panel from a sub panel, do you require another main [or disconnect switch] breaker to protect the MAIN panels bus?

Can anyone help me with this one?

<font color="#a62a2a" size="1">[ October 18, 2003 06:31 PM: Message edited by: Alectric ]</font>

[neil seidner]

I'm having a hard time understanding your question. The "main panel" sounds like a combination panel in a residential application. It would be feed by the service conductors that come from the meter and terminate in the "main breaker" or service disconnect ( is this the breaker you are talking about ?) .
Changing this breaker to a larger size to accommodate another sub panel down stream would be a code violation. The size of this breaker is based on the size of the service conductors. And the size of the busses in the "main panel " are based
on the size of this breaker.

In side this panel would be a smaller breaker supplying the first "sub panel",(is this the breaker you are talking about?) changing this breaker to a larger size would be a code violation. The size of this breaker is based on the size of the conductors to the sub panel and the size of the busses in the sub panel.

[Alectric]

From the main [combo] panel via a breaker to the first [load center] sub panel, then via another breaker from this sub to a second [load center] sub panel. Can you do this?

[neil seidner]

Yes

[Alectric]

The reason I asked this question was that a customer wanted to run another sub panel from a sub panel, which was run from an old 'Push-Matic' style [main] panel that has 'No main breaker'. Therefore, in this case it's not allowed. [Nor was the first sub panel] We've since changed the service, and every-one is SAFE & happy. [img]graemlins/thumbs_up.gif[/img]

[Alectric]

Hey Ccrash, amazing that one old [push-matic] (used to boot) breaker would cost that much, when you can buy a 32cct Federal panel complete with a 100Amp main for about $32.00 cdn. [img]graemlins/sun.gif[/img]

[neil seidner]

Excellent, Alelectric. Upgrading to newer code standards is never a wrong decision. Before I became an electrician I owned a house with a push-matic main panel(with no main breaker) and a stablok sub-panel located 3.735" from the main panel. The problem was all "new work" was added to the sub panel because it had space and new breakers cost $4.93 for the stablok. vs $87.92 for the push-matics. The end result was that the sub panel became overloaded. And nuisance tripping of the breaker feeding this panel became a problem. (some of the numbers I quoted may not be exactly as stated)