Service Rated Transfer Sw. - No OCPD

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Dennis Alwon

Dennis Alwon

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Had a meeting last week and a local inspector brought up this question. Is the below install compliant. There is art. 230.91, 408.36(depending) , and anything else you know about. Actually the definition of service conductors also comes into play also. I will post later the IAEI response-- Not sure I agree with it. BTW the TS has a center off position

Service Conductors. The conductors from the service point to the service disconnecting means.
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230.91 Location. The service overcurrent device shall be an integral part of the service disconnecting means or shall be located immediately adjacent thereto
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408.36 Overcurrent Protection. In addition to the requirement of 408.30, a panelboard shall be protected by an overcurrent protective device having a rating not greater
than that of the panelboard. This overcurrent protective device shall be located within or at any point on the supply side of the panelboard.


Exception No. 1: Individual protection shall not be required for a panelboard used as service equipment with multiple disconnecting means in accordance with 230.71.
In panelboards protected by three or more main circuit breakers or sets of fuses, the circuit breakers or sets of fuses shall not supply a second bus structure within the
same panelboard assembly.


Exception No. 2: Individual protection shall not be required for a panelboard protected on its supply side by two main circuit breakers or two sets of fuses having a combined rating not greater than that of the panelboard. A panelboard constructed or wired under this exception shall not contain more than 42 overcurrent devices. For the purposes of determining the maximum of 42 overcurrent devices, a 2-pole or a 3-pole circuit breaker shall be considered as two or three overcurrent devices, respectively.


Exception No. 3: For existing panelboards, individual protection shall not be required for a panelboard used as service equipment for an individual residential occupancy.
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ry%3D480
 
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I hope it's legal cause that is exactly how mine is set up!
Well, not exactly. I used service entrance cable not PVC and my inlet is 30 amp not 50 amp.
 
qcroanoke said:
I hope it's legal cause that is exactly how mine is set up!
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So how do you comply with 408.36. I see those conductors as feeders since the TS is the main disco and the service conductors stop at the fiorst disco.

BTW this service rated Transfer switch has a center off. Never saw one like that
 
I don't think the manual transfer switch can count as the service disconnecting means. I may be wrong about that, but I don't have time right now to look it up. The panel has sufficient overcurrent protection. But its main breaker cannot count as the building's service disconnect, unless it is located adjacent to the manual transfer switch. The problem I have is that there is no overcurrent protection for the transfer switch itself.
 
FWIW I know the UL general directory indicates that service rated transfer switches may, or may not include over current protection.
 
Dennis Alwon said:
So how do you comply with 408.36. I see those conductors as feeders since the TS is the main disco and the service conductors stop at the fiorst disco.

BTW this service rated Transfer switch has a center off. Never saw one like that
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I see what you are saying but I do comply with 230-91. They are side by side. all I did was take the service cable out of the 200 amp main breaker panel and moved it into the MTS and ran a 4 conductor cable from there to the panel separating the neutrals and grounds of course.
My MTS has a center off position.
I've never seen one that didn't.
 
iwire said:
FWIW I know the UL general directory indicates that service rated transfer switches may, or may not include over current protection.
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That is correct but it must be located adjacent to the switch. I think we comply there. The question is if the TS is the main disco then the panel conductors to the 200 amp panel are feeders. If we see that as an integral part of the TS then they are service conductors but the definition does not support that.

Charlie I don't think that is correct at least I have not seen anything that would state that
 
qcroanoke said:
I see what you are saying but I do comply with 230-91. They are side by side. all I did was take the service cable out of the 200 amp main breaker panel and moved it into the MTS and ran a 4 conductor cable from there to the panel separating the neutrals and grounds of course.
My MTS has a center off position.
I've never seen one that didn't.
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The question is if the breaker in the panelboard is on the supply side of the panelboard. I think that would be the intent. I did not read that carefully enough- I was thinking the ocpd had to be at the origin of the feeder conductors.
 
Dennis Alwon said:
So how do you comply with 408.36.
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That part is easy, I should think. It has a main breaker. That is all that is needed to protect the panel itself, and all that is needed to satisfy 408.36. The question of protecting the feeders to the panel is another matter.

 
I guess then 240.21 is relevant. That was what I was looking for. I remembered that but saw 408.36 and assumed that was it. I don't think we can look at these conductors as taps-- or can we?


240.21 Location in Circuit. Overcurrent protection shall be
provided in each ungrounded circuit conductor and shall be
located at the point where the conductors receive their supply
except as specified in 240.21(A) through (H). Conductors supplied
under the provisions of 240.21(A) through (H) shall not
supply another conductor except through an overcurrent protective
device meeting the requirements of 240.4.
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I don't understand the problem.

The OCPD has to be adjacent to the switch, if it is things are compliant. If it is not things are not compliant.
 
Dennis Alwon said:
I guess then 240.21 is relevant. That was what I was looking for. I remembered that but saw 408.36 and assumed that was it. I don't think we can look at these conductors as taps-- or can we?
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Service conductors are not taps, even though they have the same nature as taps, being protected only at the downstream end.
And I would say that the conductors between the disconnect and the service OCPD would have to be feeders, and therefore would be taps.
It is certainly unclear as to whether the service conductors end at the disconnect or at the OCPD when they are not one and the same (or at least not in the same enclosure in the case of fuses.)
Maybe the CMP felt that as long as they were short the detail of how to characterize these conductors was not worth worrying about?
 
iwire said:
I don't understand the problem.

The OCPD has to be adjacent to the switch, if it is things are compliant. If it is not things are not compliant.
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Adjacent to may be ahead of the TS also. Not sure of their intent here. Also one section contradicts another so.......... It is not a clean set of rules IMO.
 
Dennis Alwon said:
I don't think we can look at these conductors as taps-- or can we?
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I think not. Upstream of a "tap" (i.e., per 240.21) there must be either, (1) an overcurrent device and conductors that are able to be protected by that device, or (2) a transformer.

A coworker and I got into a discussion of this very subject last week. I may post a separate thread on this question, but here is a quick introduction: Look at the handbook's Exhibits 700.3 and 700.4. What protects the conductors between the generator windings and the three overcurrent devices shown in each of the Exhibits? I mention this within the present thread because it has the same implications: this is not a "tap" situation, and we are not protecting the conductors at the point at which they receive power. So why is this legal?

 
GoldDigger said:
And I would say that the conductors between the disconnect and the service OCPD would have to be feeders, and therefore would be taps.
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The problem with that assertion is that, by definition, a "feeder" must be connected to the service equipment, or must be located downstream of the service equipment. However, per the IAEI response that Dennis posted, the transfer switch and the panel collectively comprise "service equipment." So the conductors between them are service conductors, not feeders. I agree with something Dennis mentioned at the beginning of this thread: the IAEI response is not one I am ready to accept. Also, as I just mentioned, absent an OCDP upstream of the conductors between the transfer switch and the panel, I don't think we can call this a tap situation.

 
Service Equipment. The necessary equipment, usually consisting
of a circuit breaker(s) or switch(es) and fuse(s) and
their accessories, connected to the load end of service conductors
to a building or other structure, or an otherwise designated
area, and intended to constitute the main control and cutoff of
the supply.
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That certainly could include the TS and the immediately adjacent to it OCPD.
 
But if you take that reasonable approach, the field-installed wiring between disconnect and OCPD becomes internal wiring within the service equipment, putting it into an interesting NEC limbo as far as what rules apply.
 
charlie b said:
The problem with that assertion is that, by definition, a "feeder" must be connected to the service equipment, or must be located downstream of the service equipment. However, per the IAEI response that Dennis posted, the transfer switch and the panel collectively comprise "service equipment." So the conductors between them are service conductors, not feeders. I agree with something Dennis mentioned at the beginning of this thread: the IAEI response is not one I am ready to accept. Also, as I just mentioned, absent an OCDP upstream of the conductors between the transfer switch and the panel, I don't think we can call this a tap situation.

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If I am not mistaken the TS neutral was permanently bonded to the can so the upstream ocpd would make the TS a violation.
 
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