Neutral bring to disconnect

Merry Christmas
hhsting said:
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?

View attachment 2581179


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Infinity is saying no, but I am saying yes. I look at it like this... The rules for separately derived systems, in most cases parallel the rules for services. Large facilities, like the UF campus here have customer owned utilities. Those are not services, even though the entire campus distribution system is identical to a utility. The University is not a utility. That code cited, doesn't state that a transformer can only feed one system, so each system can have its own bond.
 
Upon further research you all right and wrong. Let me explain:

NEC 2017 Article 250.28(D)(3) says system bonding jumper can be installed in each enclosure. This would settle system bonding jumper at each disconnect or not correct?

However get this NEC 2017 Article 250.30(A)(1) says “…If the source is located outside of building or structure supplied, a system bonding jumper shall be installed at the grounding electrode connection in compliance with NEC 2017 Article 250.30(C)….”

My existing customer owned transformer is outside, has existing grounding electrode conductor connection to grounding ring circling the pad and NEC 2017 Article 250.30(A)(1) says system bonding shall be installed in that outdoor transformer meaning its a must.

So what does this all mean put system bonding jumper in secondary disconnects and in the outdoor transformer but then that would not comply with first part of NEC 2017 Article 250.30(A)(1) or not? Does this mean code already decided that for outdoor transformer system bonding jumper be installed in the outdoor transformer only or not??? I dont get it
 
If the conditions in the exceptions apply you basically treat it as if it was a service transformer, SBJ at source and fire pump with a grounded conductor installed.
 
hhsting said:
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.
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Where there are multiple secondary disconnects, each one gets a system bonding jumper, just like with multiple service disconnects, each one gets a main bonding jumper.
Note that both sets of secondary conductors will need to include a supply side bonding jumper.
 
Your transformer has "an" existing ground ring at the transformer. Did you read exception #2?That is pretty clearly The situation you are describing. whether you bond in the transformer of the building, you still need to bond the electrode system to all available building electrodes. The ground ring can be made part of the grounding system, or it can merely be an optional bond between the transformer metal parts and earth.


Exception No. 2: If a building or structure is supplied by a feeder from
an outdoor separately derived system, a system bonding jumper at both
the source and thefirst disconnecting means shall be permitted ifdoing
so does not establish a parallel path for the grounded conductor If a
grounded conductor is used in this manner; it shall not be smader than
the size specifiedfor the system bondingjumper but shall not be required
exception, connection through the earth shall not be considered as
providing a parallel path.
to be larger than the ungrounded conductor(s). For the purposes of this
 
2017 NEC 250.30(C): the outdoor transformer must have a GEC connection.

2017 NEC 250.30(A)(1) last sentence: there must be an SBJ at the location of the 250.30(C) GEC connection.

Therefore you must have an SBJ at the outdoor transformer.

Now given that, you may not have any SBJs at the interior SWBD or fire pump controller, unless you are utilizing 250.30(A)(1) Exception 2, which allows an additional SBJ at the first means of disconnect, provided there is no SSBJ run to that first means of disconnect. Basically letting the grounded conductor be the fault clearing path, as is done for a service.

Cheers, Wayne
 
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If using the exception, the rule also states the bonding jumper shall not create a parallel path back to the transformer.

If using a bonding jumper in the fire pump disconnect, and the exception, one would need to use a non-conductive raceway that would not cause a parallel path back to the transformer correct?

This line seems to get crossed on a much smaller scale on services where galvanized nipples are installed between a meter base and a service disconnect.

Jap>
 
Strathead said:
Actually, they each need to contain either a neutral or a supply side bonding jumper, not both.
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A customer owned transformer needs both, unless you are bonding at both the transformer and the disconnects....permitted but only under specific conditions. The supply side bonding jumper is the fault clearing path between the location of the system bonding jumper and the other end of the circuit.
 
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