Neutral bring to disconnect

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hhsting

Senior Member
Location
Glen bunie, md, us
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Junior plan reviewer
I have customer owned delta to wye 13.8kv to 480/277V system and its located outside. The transformer does not system bonding jumper i.e no neutral to ground at the transformer. However the transformer has grounding electrode conductor going to ground ring around its perimeter pad. It has 2 sets of secondary conductors provided and owned by customer. The first set of secondary conductor feeds SWBD inside Building #1. The SWBD has main bonding jumper i.e neutral to ground bond. The second sets secondary conductor feeds fire pump controller inside Building #2. Should neutral be brought from customer owned transformer to the fire pump controller? If yes then which NEC 2017 Article?
 
hhsting said:
The second sets secondary conductor feeds fire pump controller inside Building #2. Should neutral be brought from customer owned transformer to the fire pump controller?
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Yes, if there is no neutral at the fire pump service disconnect then there is nothing to connect the MBJ to. This is no different than any other service disconnect.
 
infinity said:
Yes, if there is no neutral at the fire pump service disconnect then there is nothing to connect the MBJ to. This is no different than any other service disconnect.
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Please read carefully their is no service conductors brought from the transformer. The transformer is customer owned. So those are secondary feeders brought to the fire pump controller. Does it still require neutral being brought? I dont see anything in NEC 2017 about feeders must bring neutral.
 
hhsting said:
Please read carefully their is no service conductors brought from the transformer. The transformer is customer owned. So those are secondary feeders brought to the fire pump controller. Does it still require neutral being brought? I dont see anything in NEC 2017 about feeders must bring neutral.
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I missed the customer owned part. So this a 480 volts ungrounded system?
 
infinity said:
I missed the customer owned part. So this a 480 volts ungrounded system?
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Well the customer owned transformer has grounding electrode conductor to ground ring around its pad. It has no system bonding jumper. The transformer feeds two feeders. One is going to SWBD and they put main bonding jumper in the SWBD because transformer is separately derived.

The second feeder goes to fire pump controller.

I dont know what to call that 480V ungrounded system or not?
 
infinity said:
Since it's not a service disconnect a 3Ø, 3W fire pump controller does not require a neutral.
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Sorry for light attachment but drawings has this part lighted as existing and new part bolded. Cant do much better might have to zoom in.

Just to make sure in the attached Transformer T3 is the customer owned transformer. The yellow highlighted conductor is one set of secondary feeder 3 phase plus ground goes to fire pump controller. The ECC3 is the swbd that the second set of secondary feeder feed.

The transformer is separately derived. The fire pump is powered from secondary 3 phase wye windings. Right now the fault currents goes from fire pump controller to 2 awg ground to the ground bus but has no way going back to wye windings.

If you dont bring neutral to the fire pump controller from center of wye and do neutral to ground bond in fire pump controller then I dont see how fault currents would get back to wye windings where it originated?

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Tell me if this is correct.
Customer owned transformer after the service disconnect?
Transformer Delta/Wye secondary is 480Y/277 3 phase, neutral bonded?
Fire pump controller 3 phase, 3 wire fed by a feeder with EGC and no neutral?
 
infinity said:
Tell me if this is correct.
Customer owned transformer after the service disconnect?
Transformer Delta/Wye secondary is 480Y/277 3 phase, neutral bonded?
Fire pump controller 3 phase, 3 wire fed by a feeder with EGC and no neutral?
Click to expand...

Customer owned transformer after the service disconnect?

YES

Transformer Delta/Wye secondary is 480Y/277 3 phase, neutral bonded?

NO neutral bonded in the transformer. However the transformer is delta/wye and the secondary is 480Y/277 3 phase.

Fire pump controller 3 phase, 3 wire fed by a feeder with EGC and no neutral?

YES fire pump controller 3 phase, 3 wire fed by the transformer secondary feeder with EGC and no neutral.
 
Since this is specified as a 480/277 volt system, I am going to require a neutral be run to the fire pump controller, a system bonding jumper be installed and a connection to a GEC.

In addition, since there is no system bonding jumper at the transformer, supply side bonding jumpers will be required from from the system bonding jumper in the switchboard and one from the system bonding jumper at the fire pump controller.
 
don_resqcapt19 said:
Since this is specified as a 480/277 volt system, I am going to require a neutral be run to the fire pump controller, a system bonding jumper be installed and a connection to a GEC.

In addition, since there is no system bonding jumper at the transformer, supply side bonding jumpers will be required from from the system bonding jumper in the switchboard and one from the system bonding jumper at the fire pump controller.
Click to expand...

If they run neutral to fire pump controller disconnect can I put neutral to ground bond in it fire pump controller? I would now have two secondary disconnects and one of them SWBD has neutral to ground bond.

Please see attached what I have. NEC 2017 Article 250.30(A)(1) says system bonding jumper can be at any single point on the separately derived system from the source to the first system disconnecting means.

Do I have first system disconnecting means in the attachment this post?

IMG_8985.jpg


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