Transfer equipment

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ceb58

ceb58

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Raeford, NC
I was ask a question on a quiz today and the answer has been bugging me all day.The question was can a auto. transfer switch be connected ahead of the service disconnect? Being in a rush the only thing I could come up with was no based on 701.7 (A). The questions were directed toward legally required systems. What say those more in the know than I? Where is Roger when I need him?:grin:
 
Hello Curtis, I agree with Ron but to go a little further, if the switch is going to feed Emergency Loads (article 700) all the loads would have to be classified as Emergency which would be a far stretch and hard to do.

If the Switch is feeding Legally Required Standby or Optional Loads it would be easier in classifying all the loads served as one system or the other.

Roger
 
roger said:
Hello Curtis, I agree with Ron but to go a little further, if the switch is going to feed Emergency Loads (article 700) all the loads would have to be classified as Emergency which would be a far stretch and hard to do.

If the Switch is feeding Legally Required Standby or Optional Loads it would be easier in classifying all the loads served as one system or the other.

Roger
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Roger, what does that have to do with the ATS being service rated or not. If the ATS is the main disco it must be built and installed to comply with 230.70. No?
 
chris kennedy said:
Roger, what does that have to do with the ATS being service rated or not. If the ATS is the main disco it must be built and installed to comply with 230.70. No?
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Chris, where did the question say the transfer switch was intended to be the main disconnect, you're reading your interpretation into the question which is a reason for many missed answers to exam questions.

Read the OP again and notice the question was "can a auto. transfer switch be connected ahead of the service disconnect"

Roger
 
roger said:
Chris, where did the question say the transfer switch was intended to be the main disconnect, you're reading your interpretation into the question which is a reason for many missed answers to exam questions.

Read the OP again and notice the question was "can a auto. transfer switch be connected ahead of the service disconnect"

Roger
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Yup, thanks.

My answer is yes. 695.3

Power may be supplied by the following:
1. A separate utility service or connection ahead of the main disconnecting means
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230.82,.. no .. it won't be ahead of the service disconnect ,..it will be the service disconnect or do I mis understand???
 
roger said:
Hello Curtis, I agree with Ron but to go a little further, if the switch is going to feed Emergency Loads (article 700) all the loads would have to be classified as Emergency which would be a far stretch and hard to do.

If the Switch is feeding Legally Required Standby or Optional Loads it would be easier in classifying all the loads served as one system or the other.

Roger
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Hi Roger,
The question was targeted toward generators installed at communication towers, which by there duty would be classed as legally requried systems. As I stated I answered no.:-?
 
ceb58 said:
Hi Roger,
The question was targeted toward generators installed at communication towers, which by there duty would be classed as legally requried systems. As I stated I answered no.:-?
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I believe it is still a no. Article 701.11E and 230.82 allows the "connection" to be made ahead of the service disconnect, but the conductors still need to meet the requirements of 230, which would require a seperate disconnect and overcurrent protection.Then the A.T.S. can be installed or if part of, but only after.
Rick
 
ceb58 said:
I was ask a question on a quiz today and the answer has been bugging me all day.The question was can a auto. transfer switch be connected ahead of the service disconnect? Being in a rush the only thing I could come up with was no based on 701.7 (A). The questions were directed toward legally required systems. What say those more in the know than I? Where is Roger when I need him?:grin:
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Sir, what are the loads supplied by the ATS? I believe it is not intended for the whole electrical system as you're saying that it is directed toward legally required systems.

From my point of view, you are referring to another service disconnect that is intended for legally required system. If that is the case, NEC 2005 230.82 (5) allowed "Taps used only to supply load management devices, circuits for standby power systems, fire pump equipment, and fire and sprinkler alarms, if provided with service equipment and installed in accordance with requirements for serviceentrance conductors."

If the ATS is not rated as service equipment, then it is not allowed to connect ahead of the service disconnect, but if the ATS is service equipement rated, then it is allowed and you don't need the succeeding service disconnect as the ATS rated as service equipment already serve the function of the service equipment.
 
enteng14 said:
Sir, what are the loads supplied by the ATS? I believe it is not intended for the whole electrical system as you're saying that it is directed toward legally required systems.

From my point of view, you are referring to another service disconnect that is intended for legally required system. If that is the case, NEC 2005 230.82 (5) allowed "Taps used only to supply load management devices, circuits for standby power systems, fire pump equipment, and fire and sprinkler alarms, if provided with service equipment and installed in accordance with requirements for serviceentrance conductors."

If the ATS is not rated as service equipment, then it is not allowed to connect ahead of the service disconnect, but if the ATS is service equipement rated, then it is allowed and you don't need the succeeding service disconnect as the ATS rated as service equipment already serve the function of the service equipment.
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The question I had to answer was, is a automatic transfer switch allowed to be installed ahead of the service disconnect? The question was on a quiz I had to take for a job interview, however the questions were targeted toward specific applications of generators. These generators supply full power to a 10'x 15' building that houses the radio equipment for communication towers. The load consist of the lighting for the building, ac unit and the radio transmission equipment that's all. No fire pumps,sprinklers. As I stated I answered no based on 701.7A (2008)
 
Is an auto/trans switch allowed to be installed ahead of the service disconnect?

Sure, why not. With that limited info what else could you say.
 
benaround said:
Is an auto/trans switch allowed to be installed ahead of the service disconnect?

Sure, why not. With that limited info what else could you say.
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Actually the answer is no, transfer switches can not be installed ahead of the service disconnect. See 230.82

If you need to do that you must use a service rated transfer switch which becomes the service disconnect.
 
iwire said:
Actually the answer is no, transfer switches can not be installed ahead of the service disconnect. See 230.82

If you need to do that you must use a service rated transfer switch which becomes the service disconnect.
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Bob, So can a service rated auto/trans switch be installed up stream of an

existing service disconnect for a gen. install. Yes. I'm saying with the limited

info on the question either answer could be right.

If a customer asked you,' can you put an ats there,Bob' I bet you would say

NO PROBLEM. :)
 
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