Portable Generator Bonding

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session88

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I have a customer that has a Honda EM5000SX Portable Generator. He wants to use it as emergency backup power to his house.
The Neutral is not bonded at the Gen. I confirmed with Ohm Meter. The gen. manual also states that it is not bonded. I think some people call this a "Floating Neutral"

I would like to install a basic Manual Transfer Switch next to the outside service/meter. The gen.'s 240V L14-30 will feed thru a male gen. wall receipt. into the TS.

I assume I should leave the Neutrals Unswitched at the TS.

Should I Bond the Generators Neut. to Ground Bar inside the TS and connect that to the Service Electrode (ground rod)? Thanks.
 

George Stolz

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I assume I should leave the Neutrals Unswitched at the TS.
Agreed.
Should I Bond the Generators Neut. to Ground Bar inside the TS and connect that to the Service Electrode (ground rod)? Thanks.
No, by not switching the neutrals you do not have a separately derived system, and no connection to the building grounding electrodes are required. Connecting the neutral to the equipment grounding terminals of the TS would be a code violation.
 

George Stolz

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But would that green wire only be an EGC or would it also be a GEC or bond wire in the separately derived case?

It's unlikely to route a GEC through the raceway with the circuit conductors due to complications arising from 250.64, and it would not be the "effective ground fault current path" you referred to.

Whether the green conductor between the generator and the TS is a supply side bonding jumper or an equipment grounding conductor is almost an issue of semantics - but given the description of a portable generator being put into permanent fixed service, the disconnecting means (edit: OCPD) is integral to the generator, meaning that the conductor in question is an EGC.

I would think if the generator is an SDS then it would have its own grounding electrode system.

I would say it would be required to have a GEC routed to the structure's grounding electrodes per 250.30 if the neutral were switched.

Things get much less complicated leaving the neutral unswitched.
 
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ActionDave

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...I would say it would be required to have a GEC routed to the structure's grounding electrodes per 250.30 if the neutral were switched.
That is a better way of saying what I was thinking, "grounding electrode system" seemed like an easy way to sum things up.

Things get much less complicated leaving the neutral unswitched.
No doubt.
 

kwired

Electron manager
Location
NE Nebraska
If you connect it as a non separately derived system, you connect the green conductor in the cord to the EGC of the premises (the neutral bus if the connection is at service equipment is acceptable as the neutral and EGC are essentially the same point at service equipment) and to the EGC pin of the generator receptacle which is bonded to the generator frame. You since you have no separately derived system, you still have a grounding electrode system and the generator neutral is still connected to it via the main or system bonding jumper. The generator EGC is also bonded via main/system bonding jumper.

I believe they have tried to complicate this in recent codes for smaller portable generators,(less then 15kVA I believe) but really don't understand why. Use the generator stand alone and you have an ungrounded system - actually quite safe setup. Connect it to a premises wiring system as a non separately derived system and it becomes self bonded when plugged in if done properly. My only guess is they don't like the use of a plug and receptacle to rely on for such bonding, yet we do it with every plug and receptacle for other equipment.
 

session88

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Location
USA
Yes there is a Main Breaker/Disconnect between the POCO Meter and MTS.

And I will look at Art. 702 about signage. Thanks for the heads up.
 
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