Detached Building Art. 225 Question

[augie47]

Another inspector posed this question to me in regard to Art 225 ('08)
225.33 allows the disconnecting means for a detached building to consist of no more than six circuit breakers.
225.38(B) calls for the "simultaneous disconnect of all ungrounded supply conductors"
Does this mean if one uses the six circuit rule that you would need a listed handle-tie for the up to six breakers ?

A second question deals with 225.39. (D) which requires the disconnect means have a rating of not less than 60 amps.
If one has a 100 amp MLO panel with (3) 20 amp s.p. breakers on a 240/120 supply does that meet the 60 amp requirement ?

 

[david luchini]

Another inspector posed this question to me in regard to Art 225 ('08)
225.33 allows the disconnecting means for a detached building to consist of no more than six circuit breakers.
225.38(B) calls for the "simultaneous disconnect of all ungrounded supply conductors"
Does this mean if one uses the six circuit rule that you would need a listed handle-tie for the up to six breakers ?

I don't believe that the section requires simultaneous disconnection of all six breakers at the same time. 225.38 says that each disconnecting means shall simultaneously disconnect all of the ungrounded supply conductors that it controls. I read that as treating each of the six disconnects individually.

A second question deals with 225.39. (D) which requires the disconnect means have a rating of not less than 60 amps.
If one has a 100 amp MLO panel with (3) 20 amp s.p. breakers on a 240/120 supply does that meet the 60 amp requirement ?

225.39 says that where there is more than one switch, as permitted by 225.33, combining the ratings of all of the switches to determine the rating of the disconnect shall be allowed. However, its a bit unclear as to whether 225.33(B) requires the single pole units to be tied together and counted as a single switch, so I'm on the fence with this one.

 

[Cow]

How many main lug residential loadcenters meet the requirements of 225.36? It was always my thought that you'd have to use a main breaker panel to meet this requirement.

 

[augie47]

How many main lug residential loadcenters meet the requirements of 225.36? It was always my thought that you'd have to use a main breaker panel to meet this requirement.

'

Unless I've been misreading them for years, most do. The ones I see normally have a tag "suitable for use as service equipment when no more than 6....."

 

[augie47]

I don't believe that the section requires simultaneous disconnection of all six breakers at the same time. 225.38 says that each disconnecting means shall simultaneously disconnect all of the ungrounded supply conductors that it controls. I read that as treating each of the six disconnects individually.



225.39 says that where there is more than one switch, as permitted by 225.33, combining the ratings of all of the switches to determine the rating of the disconnect shall be allowed. However, its a bit unclear as to whether 225.33(B) requires the single pole units to be tied together and counted as a single switch, so I'm on the fence with this one.

In his case, we have (3) s.p. 20 amp breakers therefore we have a situation where the sum of the breakers = 60, but the sum of phase A is only 40 and B only 20. Does that suffice having a "combined rating of 60 amps" as opposed to a 60 amp dp breaker ?
If the panel is rated at 100 amp, does that satisfy 225.39(D) regardless of the breaker sizes ??
I normally see a panel with a main on detached structures with a feeder. Obviously I find the "6 main" a but confusing.

 

[david]

In his case, we have (3) s.p. 20 amp breakers therefore we have a situation where the sum of the breakers = 60, but the sum of phase A is only 40 and B only 20. Does that suffice having a "combined rating of 60 amps" as opposed to a 60 amp dp breaker ?
If the panel is rated at 100 amp, does that satisfy 225.39(D) regardless of the breaker sizes ??
I normally see a panel with a main on detached structures with a feeder. Obviously I find the "6 main" a but confusing.

225.38(A) seems to indicate the breaker not the rating of the panel.

225.39 (C) is the only one that calls out a two pole disconnect, or at least a three wire feed.