- Location
- Massachusetts
georgestolz said:
Keep in mind the branch circuit breakers will serve that purpose.
separate strutures disconnects
- Thread starter stew
- Start date
- Status
Keep in mind the branch circuit breakers will serve that purpose.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Perhaps not in all circumstances. If all six circuits installed were 20 amp multioutlet branch circuits, and were all physically loaded to 80%, then none of the branch circuits would trip. The feeder overcurrent device would.
Could happen. 8)
Could happen. 8)
- Location
- Massachusetts
George that is true but not relevant.
Your assuming. :wink:
Nowhere does 225.40 state the total rating of the branch breakers must be less than the feeder breaker.
Only that branch-circuit overcurrent devices shall be of a lower ampere rating than the feeder overcurrent device.
Your assuming. :wink:
Nowhere does 225.40 state the total rating of the branch breakers must be less than the feeder breaker.
Only that branch-circuit overcurrent devices shall be of a lower ampere rating than the feeder overcurrent device.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Charlie's Rule in full effect. :shock:
I am positive that's not what they intended it to say, but you're right, that's what it says. :roll:
I am positive that's not what they intended it to say, but you're right, that's what it says. :roll:
- Location
- Massachusetts
I think you made a very reasonable assumption.
However regardless of the breaker sizes a fault in a branch circuit may well dump the feeder breaker as well as the branch circuit breaker.
The instantaneous trip ratings of breakers from 15 to a 100 are very close to each other.
However regardless of the breaker sizes a fault in a branch circuit may well dump the feeder breaker as well as the branch circuit breaker.
The instantaneous trip ratings of breakers from 15 to a 100 are very close to each other.
- Location
- Massachusetts
georgestolz said:
Thinking on this some more I do not see a way this could mean what you want it to mean.
Say the separate building is large, I install a 240/120 single phase 40 circuit panel with 50% 15 amp single pole breakers and 50% 20 amp single pole breakers.
Would you say I need a 350 amp feeder, breaker, and therefore panel?
10 x 15 amps = 150
10 x 20 amps = 200
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
No, I'm saying that if the feeder supplying the panel is protected by a 100 amp OCPD, then there should be a 90 amp OCPD on the load side of the feeder, before the branch circuits. While it wouldn't mean much in a fault condition, it would mean a lesser loss in downtime under a slow overload condition. That would be the closest thing to sensible in what this section is implying.
In truth, the requirement in 225.40 is pretty useless IMO anyway, as the fault scenario makes selective coordination a pretty fruitless endeavor.
- Location
- Massachusetts
georgestolz said:
But that is not even close to what 225.40 requires it specifies the branch circuit breakers.
What I get from this is it is telling us no single branch circuit may be larger than the feeder suppling it.
Kind of a no brainier but it must have been an issue to someone. :?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
George:
Why does the equipment need a service entrance label if the neutral is not going to be bonded to the ground?
According to UL (and yes there are more requirements):
"Suitable only for use as service entrance" means the neutral and ground are bonded at the factory and are not separable.
"Suitable for use as service entrance" means the neutral and ground may be bonded in the field.
"Not suitable for use as service entrance" means there are no manufacturer supplied neutral to ground bonding provisions.
Why does the equipment need a service entrance label if the neutral is not going to be bonded to the ground?
According to UL (and yes there are more requirements):
"Suitable only for use as service entrance" means the neutral and ground are bonded at the factory and are not separable.
"Suitable for use as service entrance" means the neutral and ground may be bonded in the field.
"Not suitable for use as service entrance" means there are no manufacturer supplied neutral to ground bonding provisions.
- Location
- Massachusetts
jim dungar said:
Jim I don't know why it is a requirement but it seems fairly clear.
If the panel in question is being used as the disconnecting means required by 225.31 we are stuck with this.
There is no mention of bonding or not bonding in that NEC requirement.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Bob,
I think I see it now.
The NEC phrase "suitable for use as" means the neutral has the ability to be bonded if needed.
I think I see it now.
The NEC phrase "suitable for use as" means the neutral has the ability to be bonded if needed.
stew
Senior Member
- Location
- federal way,washington
in summation if i serve the outbuilding with a single circuit I must have a sanp switch or other means for disconnect that is service rated. If I serve the outbuilding from a breaker in the main panel I may use a 6 throw arraingment as my means of dissconnect. If I serve from a breaker in the main panel to say 10 circuit panel I must have a service rated disconnecting means at the structure and the panel breaker must have a lower???? value than the disconnect? Somehow this last scenario confuses me because the disconnect at the building is just that not overcurrent protection. I thought that the panel breaker was the feeder overcurrent device and the panel disconnect at the outbuilding was only there to dissconnect the outbuilding. What if you used a 100 amp feeder and a nonfused 200 amp disconnect?
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Sorry to throw the wrench in the works. None of the branch circuit OCPD's can be larger than the feeder OCPD. Nothing more. You'd have to try hard to violate that section.stew said:
100% correct.stew said:
Very legal.stew said:
Sure it does. Is there an exception? Then it applies.mpd said:
Amen.mpd said:
But it's nice to know there's options.
stew
Senior Member
- Location
- federal way,washington
george I understand that none of the branch breakers may be larger than the feeder breakers. I guess where I get confused is where it was stated that the disconnecting means had to be lower value than the feeder breaker. 100 amp feeder breaker 200 amp circuit breaker at the sub for disconnecting the outbuilding and all branch breakers smaller than the feeder breaker is ok as I understand it. Myabe I just misunderstood somene elses reply.
jwelectric
Senior Member
- Location
- North Carolina
Here is what UL states that this remote panel has to conform with. Notice the bold type. Also notice the requirement to label the service disconnect in line 24. This is the 2004 Guide so the NEC references will fall under the 2002 cycle. For a complete reading http://www.ul.com/regulators/panelboards.pdf
SUITABLE FOR USE AS SERVICE EQUIPMENT
18. These are the basic requirements that a panelboard rated 600 volts or less must meet in order to be used as service equipment:
A. Service disconnecting means must be provided.
B. Each service disconnect provided must have a switching feature that disconnects all conductors from the service-entrance conductors and that is suitable for use as a service disconnect. There is one exception: the neutral service conductor can be disconnected by removing the wires from the pressure wire connectors on the service neutral bus as noted in Section 230.75 (230?75) of the NEC.
In general, snap, toggle or similar switches, are not acceptable because their internal electrical spacing are too small. The exception in Section 225.36 (230?84(b)) of the NEC for branch circuit switches used to disconnect garages and out buildings on residential property does not apply to the service disconnects in a panelboard.
Circuit breakers, either molded case, fused, or in combination with ground fault circuit interrupters, are suitable for use as service disconnects. Other devices that are used to protect individual circuits, circuits within equipment or appliances, or circuit protectors without on and off features, are not suitable for use as service disconnects.
22. Some panelboards may have the required number of handles and service overcurrent devices, when the maximum number of the smallest units are installed and used without handles or ties or similar devices. These panelboards may have the shorter marking ?Suitable for use as service equipment? or ?Suitable only for use as service equipment.? The shorter marking is suitable for Class CTL (circuit limited) lighting and appliance panelboards since they cannot have more than two main overcurrent protective devices as specified in Section 408.16(A) (384-16(a)) of the NEC.
23. Class CTL lighting and appliance panelboards without main overcurrent protection usually are not marked suitable for service equipment use. Such panelboards, with not more than 10 percent of theircovercurrent devices rated 30 amperes or less, however, may be suitable for use as service equipment. They are marked ?Suitable for use as service equipment when not more than six main disconnecting means are provided and when not used as a lighting and appliance branch-circuit panelboard; see Section 408.14 (384?14) of the NEC.?
24. A panelboard intended for service equipment use must have the marking ?Service Disconnects? near the switch or circuit breaker handles. If this is not done in the factory, pressure sensitive labels must be provided. This marking identifies the service disconnects when branch disconnects are also present. This is required by Section 230.70(B) (230?70) of the NEC.
For what ever reason that I cannot understand there is a misconception that a panel at a remote building with six or less single pole breakers that protect branch circuits will fulfill the requirements of 225.33(B). This is not true no more that the assumption that six or less single pole breakers will fulfill the requirements of 230.71(B). Both of these sections have the same wording which states that handle ties shall be permitted on multiwire circuits. It does not say that handle ties can be used on multiple circuits.
In the UL Marking Guide it clearly states that in order to be listed as ?Suitable for use as service equipment? while being used as a lighting and appliance panelboard not more than two mains is required.
SUITABLE FOR USE AS SERVICE EQUIPMENT
18. These are the basic requirements that a panelboard rated 600 volts or less must meet in order to be used as service equipment:
A. Service disconnecting means must be provided.
B. Each service disconnect provided must have a switching feature that disconnects all conductors from the service-entrance conductors and that is suitable for use as a service disconnect. There is one exception: the neutral service conductor can be disconnected by removing the wires from the pressure wire connectors on the service neutral bus as noted in Section 230.75 (230?75) of the NEC.
In general, snap, toggle or similar switches, are not acceptable because their internal electrical spacing are too small. The exception in Section 225.36 (230?84(b)) of the NEC for branch circuit switches used to disconnect garages and out buildings on residential property does not apply to the service disconnects in a panelboard.
Circuit breakers, either molded case, fused, or in combination with ground fault circuit interrupters, are suitable for use as service disconnects. Other devices that are used to protect individual circuits, circuits within equipment or appliances, or circuit protectors without on and off features, are not suitable for use as service disconnects.
22. Some panelboards may have the required number of handles and service overcurrent devices, when the maximum number of the smallest units are installed and used without handles or ties or similar devices. These panelboards may have the shorter marking ?Suitable for use as service equipment? or ?Suitable only for use as service equipment.? The shorter marking is suitable for Class CTL (circuit limited) lighting and appliance panelboards since they cannot have more than two main overcurrent protective devices as specified in Section 408.16(A) (384-16(a)) of the NEC.
23. Class CTL lighting and appliance panelboards without main overcurrent protection usually are not marked suitable for service equipment use. Such panelboards, with not more than 10 percent of theircovercurrent devices rated 30 amperes or less, however, may be suitable for use as service equipment. They are marked ?Suitable for use as service equipment when not more than six main disconnecting means are provided and when not used as a lighting and appliance branch-circuit panelboard; see Section 408.14 (384?14) of the NEC.?
24. A panelboard intended for service equipment use must have the marking ?Service Disconnects? near the switch or circuit breaker handles. If this is not done in the factory, pressure sensitive labels must be provided. This marking identifies the service disconnects when branch disconnects are also present. This is required by Section 230.70(B) (230?70) of the NEC.
For what ever reason that I cannot understand there is a misconception that a panel at a remote building with six or less single pole breakers that protect branch circuits will fulfill the requirements of 225.33(B). This is not true no more that the assumption that six or less single pole breakers will fulfill the requirements of 230.71(B). Both of these sections have the same wording which states that handle ties shall be permitted on multiwire circuits. It does not say that handle ties can be used on multiple circuits.
In the UL Marking Guide it clearly states that in order to be listed as ?Suitable for use as service equipment? while being used as a lighting and appliance panelboard not more than two mains is required.
- Status