"Six Throws" Grouping of Service Disconnects via (6) Inside 42 Circuit Load Centers

[cottora]

The definition of 'grouping' is subject to interpretation. Most of the AHJs I have dealt with would consider the interior of a shipping contain as 1 location, so the disconnecting means would not need to be contiguous.

Does not contiguous equal not grouped together it in the same building/room? Thanks

 

[Dennis Alwon]

So if the trany is outside and you have 6 different feeders entering one container how do you get around 225.30

225.30 Number of Supplies. A building or other structure
that is served by a branch circuit or feeder on the load side of a
service disconnecting means shall be supplied by only one
feeder or branch circuit unless permitted in 225.30(A)
through (E). For the purpose of this section, a multiwire
branch circuit shall be considered a single circuit.
Where a branch circuit or feeder originates in these additional
buildings or other structures, only one feeder or branch
circuit shall be permitted to supply power back to the original
building or structure, unless permitted in 225.30(A)
through (E).
(A) Special Conditions. Additional feeders or branch circuits
shall be permitted to supply the following:
(1) Fire pumps
(2) Emergency systems
(3) Legally required standby systems
(4) Optional standby systems
(5) Parallel power production systems
(6) Systems designed for connection to multiple sources of
supply for the purpose of enhanced reliability
(7) Electric vehicle charging systems listed, labeled, and identified
for more than a single branch circuit or feeder
(B) Special Occupancies. By special permission, additional
feeders or branch circuits shall be permitted for either of the
following:
(1) Multiple-occupancy buildings where there is no space
available for supply equipment accessible to all occupants
(2) A single building or other structure sufficiently large to
make two or more supplies necessary
(C) Capacity Requirements. Additional feeders or branch
circuits shall be permitted where the capacity requirements are
in excess of 2000 amperes at a supply voltage of 1000 volts or
less.
(D) Different Characteristics. Additional feeders or branch
circuits shall be permitted for different voltages, frequencies,
or phases, or for different uses such as control of outside lighting
from multiple locations.
(E) Documented Switching Procedures. Additional feeders or
branch circuits shall be permitted to supply installations under
single management where documented safe switching procedures
are established and maintained for disconnection.

 

[MAC702]

Does he not meet paragraph C?

 

[Dennis Alwon]

Does he not meet paragraph C?

I don't believe the voltage is 1000v or more. Also do these panels only feed the one building? I would be surprised

 

[cottora]

I don't believe the voltage is 1000v or more. Also do these panels only feed the one building? I would be surprised

I think paragraph C is 1000 volts or less. We are 208v, 3600 amps all serving load in the same building/container.

 

[texie]

If I understand correctly, the OP has 6, 600 amp breakers connecting to the secondary of a transformer.
How do you comply with Table 450.3(B) Note 2?
Is there a main OCPD at the transformer?
What size is the transformer?

 

[Dennis Alwon]

I think paragraph C is 1000 volts or less. We are 208v, 3600 amps all serving load in the same building/container.

My bad on the voltage. So does building require all that capacity?

 

[cottora]

If I understand correctly, the OP has 6, 600 amp breakers connecting to the secondary of a transformer.
How do you comply with Table 450.3(B) Note 2?
Is there a main OCPD at the transformer?

if we stay within 10 feet then i don’t think we need OPCD protection at transformer.

 

[texie]

if we stay within 10 feet then i don’t think we need OPCD protection at transformer.

The six main breaker total value can not exceed the value allowed for a single breaker in Table 450.3(B).

 

[electrofelon]

if we stay within 10 feet then i don’t think we need OPCD protection at transformer.

Note transformer secondary conductor protection, and transformer protection are two different things. Articles 240.21 and 450.3 respectively. You might not need any transformer protection on the secondary depending on some specifics. See Texie's reference.

 

[cottora]

Note transformer secondary conductor protection, and transformer protection are two different things. Articles 240.21 and 450.3 respectively. You might not need any transformer protection on the secondary depending on some specifics. See Texie's reference.

Thanks. We are thinking about having an MV pad-mounted fused switchgear where we take utility service and then 7200/12470Y to 120/208Y 1,500kVa Transformer (the high side protected by the pad-mounted switchgear.

 

[electrofelon]

Thanks. We are thinking about having an MV pad-mounted fused switchgear where we take utility service and then 7200/12470Y to 120/208Y 1,500kVa Transformer (the high side protected by the pad-mounted switchgear.

Are you sure they will give you primary service for that? What is the advantage of that over taking service at 208Y/120 and letting the POCO deal with all the MV stuff?

 

[cottora]

Are you sure they will give you primary service for that? What is the advantage of that over taking service at 208Y/120 and letting the POCO deal with all the MV stuff?

The POCO will provide service as Substation or Primary (which means the customer must provide the transformer and power is taken either from the substation or MV distribution line if "Primary"). It is less costly from a rate standpoint.

 

[jap]

I may be missing something, but, I don't see the need to group the panels that are tapped from the transformer on the secondary side when you have a customer owned HV Swich on the primary side of the Transformer as a single primary disconnect.


JAP>

 

[cottora]

I may be missing something, but, I don't see the need to group the panels that are tapped from the transformer on the secondary side when you have a customer owned HV Swich on the primary side of the Transformer as a single primary disconnect.


JAP>

Ideally, we would be able to spread the panels throughout the room. However, will we run into a violation because the building does not then have a centralized location to disconnect the taps (similar to the grouping and six throws rule that is applicable to service feeds)? I think that the tap rule requires that the conductor's disconnect (in this case, we use the panel main) must be in a readily assessable location.

 

[jap]

Ideally, we would be able to spread the panels throughout the room. However, will we run into a violation because the building does not then have a centralized location to disconnect the taps (similar to the grouping and six throws rule that is applicable to service feeds)? I think that the tap rule requires that the conductor's disconnect (in this case, we use the panel main) must be in a readily assessable location.

Someone may correct me, but, you don't need a centralized place to disconnect the taps if you own the primary switch that's feeding the pad mount transformer.

You can kill the transformer (or Service) with the 1 HV switch that's ahead of it.

The Main OCPD in the individual panels are there to protect the tap conductors, not to be utilized as a 6 movement rule to disconnect the service.

The 1 primary switch ahead of the transformer is disconnecting the service, the conductors to the panels are feeders.

You are allowed up to 6 movements to completely disconnect the service from a building. If you have a customer owned primary switch that will kill the servce, there's no need to introduce the 6 movement rule.

JAP>

 

[kwired]

If the transformer is not utility owned then the medium voltage is the service voltage - you still need a service disconnecting means that complies with art 230 on your medium volts service conductors.

The secondary of the transformer is a separately derived system. Tap rules in 240.21 do apply to the secondary conductors.

If the transformer is not in or attached to (or possibly immediately adjacent to - code doesn't really give a distance before it is not considered a separate structure) then the feeder(s) supplying a separate structure need to comply with art 225 part II. Six disconnect rule in there is basically the same as it is in art 230.

 

[jap]

If the transformer is not utility owned then the medium voltage is the service voltage - you still need a service disconnecting means that complies with art 230 on your medium volts service conductors.

The secondary of the transformer is a separately derived system. Tap rules in 240.21 do apply to the secondary conductors.

If the transformer is not in or attached to (or possibly immediately adjacent to - code doesn't really give a distance before it is not considered a separate structure) then the feeder(s) supplying a separate structure need to comply with art 225 part II. Six disconnect rule in there is basically the same as it is in art 230.

I'm looking back a post #51. If they have a MV Switchgear lineup with a Fused Disconnect feeding a Transformer, then, Panels are tapped off of the secondary of the transformer, why is a 2nd disconnect (or 6 movements or less) needed on the secondary side of the Transfomer when the primary switch would disconnect the service conductors in one throw?

JAP>

 

[jap]

Never mind.

JAP>

 

[cottora]

If the transformer is not utility owned then the medium voltage is the service voltage - you still need a service disconnecting means that complies with art 230 on your medium volts service conductors.

The secondary of the transformer is a separately derived system. Tap rules in 240.21 do apply to the secondary conductors.

If the transformer is not in or attached to (or possibly immediately adjacent to - code doesn't really give a distance before it is not considered a separate structure) then the feeder(s) supplying a separate structure need to comply with art 225 part II. Six disconnect rule in there is basically the same as it is in art 230.

Thanks! This could help us solve a problem (and reduce cost). I cannot find the applicable text regarding what an allowable distance is for the transformer to disconnect rule (I assume that such a transformer must have a disconnect to even be considered?).

Thanks