Portable Genny used as SDS

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K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
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Electrician
This may be one for 'safety', but here goes.

Scenario:

Complaint originated as an issue with an amateur radio. Complainant states that power is supplied from a portable generator to a 13.8 volt power supply that runs the radio.

This was on an amateur radio forum and the issue swayed to bonding and grounding.

Speaking with the complainant, I found that he is using a portable Kohler (like a 4k) connected (plug at the genny recep and hard wired at the other end) to the line side of a 200 amp panel meant to be used as a service for a POCO connection that was never made. There is no utility power anywhere on the property. There is one ground rod at the panel and none at the generator. Only 120 volts are being used and the panel is fed with one hot, one neutral and one grounding conductor.

OK, so now we no longer have a portable generator, we have an SDS. Do portable generators have to be listed for use as an SDS and if so, what is the likelihood of a 4k having such a listing?

If OK to use as an SDS, how is this to be grounded? My thoughts would be to emulate the utility, but with only 120 volts????

If deemed an SDS, the system must be grounded. If we sink a couple of electrodes at the generator, is bonding to the electrode at the premises panel required? If so, since there is already a grounding conductor in the cord, wouldn't that make for a parallel run?

My thoughts are that his installation is unsafe as it is and he may not be able to use a 120 volt generator to feed an entrance panel.

So, let's say he gets a 120/240 volt generator. My thoughts, as stated, would be to emulate the utility, bond the neutral and ground at the genny, run a three wire connection to the panel and then re-establish the ground at that point. Electrodes would be placed at the genny, and an additional one added to the premises. NO bonding other than the third wire of the three wire feed would exist.

Which still leaves the issue of OCP. But one issue at a time for this feeble mind, if you would please. :roll:

Thanks all!
 

Smart $

Esteemed Member
Location
Ohio
So far I don't see anything unsafe about this system. The single ground rod at the panel is questionable at best.

In order for a generator to be connected as an SDS, it must be permanantly installed. Even if someone bolted a portable generator to a concrete slab, I still wouldn't consider it permanantly installed. Additionally, permanantly installed generators can be connected as a non-SDS. Also, and most notably, you cannot have an SDS with only one electrical system.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
So far I don't see anything unsafe about this system. The single ground rod at the panel is questionable at best.

In order for a generator to be connected as an SDS, it must be permanantly installed. Even if someone bolted a portable generator to a concrete slab, I still wouldn't consider it permanantly installed. Additionally, permanantly installed generators can be connected as a non-SDS. Also, and most notably, you cannot have an SDS with only one electrical system.

Not according to Article 100 of the NEC. (Page 100 in the '05) See both the definitions of SDS and Service, which follows. There is no utility, thus no service, thus any electrical supply becomes an SDS.
 

Smart $

Esteemed Member
Location
Ohio
Not according to Article 100 of the NEC. (Page 100 in the '05) See both the definitions of SDS and Service, which follows. There is no utility, thus no service, thus any electrical supply becomes an SDS.
Ooops... my bad. You are correct. However, the specific requirements of grounding a portable generator exclude it from GES-type grounding under the provisions of 250.34(A). The SDS and other grounding requirements start at the plug.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
Ooops... my bad. You are correct. However, the specific requirements of grounding a portable generator exclude it from GES-type grounding under the provisions of 250.34(A). The SDS and other grounding requirements start at the plug.

Look at condition 1 of 250.34(A).

The generator is not supplying cord and plug equipment. It is supplying a 200 amp 240 volt circuit breaker in an entrance panel which has a ground rod.
 

Smart $

Esteemed Member
Location
Ohio
Look at condition 1 of 250.34(A).

The generator is not supplying cord and plug equipment. It is supplying a 200 amp 240 volt circuit breaker in an entrance panel which has a ground rod.

...I found that he is using a portable Kohler (like a 4k) connected (plug at the genny recep and hard wired at the other end) to the line side of a 200 amp panel. ...
Refer to Article 100 definition of "equipment".
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
Refer to Article 100 definition of "equipment".

I did.

However, as I read 250.34, the genny must ONLY supply cord and plug connected equipment or equipment attached to the generator. The other breakers in the panel that are connected to the main are not cord and plug connected, but are as much equipment as the main, (even if it is deemed that a main could be construed as cord and plug connected equipment). Also, any receptacle wired to the breakers is equipment that is not cord and plug connected.
 
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SG-1

Senior Member
The neutral conductor is bonded to the generator frame to produce the EGC for the 120V. I do not advocate removing this bond because at some point a cord operated load will get plugged in.

The 200A panel probably has a main bonding jumper as well.
If so, current is dividing between the EGC & the neutral. I would disconnect the MAIN BONDING JUMPER in the panel, because it already exists at the generator.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
The neutral conductor is bonded to the generator frame to produce the EGC for the 120V. I do not advocate removing this bond because at some point a cord operated load will get plugged in.

The 200A panel probably has a main bonding jumper as well.
If so, current is dividing between the EGC & the neutral. I would disconnect the MAIN BONDING JUMPER in the panel, because it already exists at the generator.

If that is done, now all the grounds and neutrals would have to be separated as well. I'm not saying that's bad, just pointing out that there would be more to it than just removing the jumper (if it's even there)
 

SG-1

Senior Member
If that is done, now all the grounds and neutrals would have to be separated as well. I'm not saying that's bad, just pointing out that there would be more to it than just removing the jumper (if it's even there)


I would think they already are. My panel is from 1974 & they are seperated.
There is no ground bar then ?

I also suspect there are lights & maybe a coffee maker too.
 

Smart $

Esteemed Member
Location
Ohio
I did.

However, as I read 250.34, the genny must ONLY supply cord and plug connected equipment or equipment attached to the generator. The other breakers in the panel that are connected to the main are not cord and plug connected, but are as much equipment as the main, (even if it is deemed that a main could be construed as cord and plug connected equipment). Also, any receptacle wired to the breakers is equipment that is not cord and plug connected.
Everything supplied via the cord and plug plugged into the generator's receptacle is cord-and-plug connected. Under this subsection, it makes no difference how the equipment is interconnected on the other end of the cord.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
I would think they already are. My panel is from 1974 & they are seperated.
There is no ground bar then ?

I also suspect there are lights & maybe a coffee maker too.

Must be a local thing. Here they never separated are as they are bonded anyway. In a sub panel it's different.

The loads are lights, TV, power supply for radio, probably a coffee maker....they are running the whole house off the genny. No pump, gravity feed for water via PVC and all cooking / heating is done via propane.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
Everything supplied via the cord and plug plugged into the generator's receptacle is cord-and-plug connected. Under this subsection, it makes no difference how the equipment is interconnected on the other end of the cord.

I disagree.

But I posted here to get other folks input.

Is there an exact definition of cord and plug connected equipment? I couldn't find any.

Also, the wording is not 'anything supplied by the receptacles', it pertains to a certain kind of equipment.
 
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SG-1

Senior Member
Must be a local thing. Here they never separated are as they are bonded anyway. In a sub panel it's different.

The loads are lights, TV, power supply for radio, probably a coffee maker....they are running the whole house off the genny. No pump, gravity feed for water via PVC and all cooking / heating is done via propane.

I have a outside disconnect ahead of my main panel. That explains that.

This MAIN Breaker is built into the generator.
 

Smart $

Esteemed Member
Location
Ohio
I disagree.

But I posted here to get other folks input.

Is there an exact definition of cord and plug connected equipment? I couldn't find any.

Also, the wording is not 'anything supplied by the receptacles', it pertains to a certain kind of equipment.
The wording is "cord-and-plug-connected equipment through receptacles mounted on the generator". Where do you see it as specifying a certain kind of equipment?
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
The wording is "cord-and-plug-connected equipment through receptacles mounted on the generator". Where do you see it as specifying a certain kind of equipment?

I see 'cord and plug connected equipment' to be a type of equipment, which is specified, as opposed to any equipment powered through the receptacles mounted on the generator.

This is why I am looking for a written definition.

My feeling is that in order to be 'cord and plug connected equipment' it has to be designed and manufactured that way. I don't see a breaker as being cord and plug connected equipment.
 

iwire

Moderator
Staff member
Location
Massachusetts
I see 'cord and plug connected equipment' to be a type of equipment, which is specified, as opposed to any equipment powered through the receptacles mounted on the generator.

I agree with you and this topic in the past has gone 100s of posts with no clear resolution.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
I agree with you and this topic in the past has gone 100s of posts with no clear resolution.

What would be the best advice I can offer the guy? I don't think there is a good way to connect a 120 volt generator designed to be used as a portable to a permanently installed entrance panel in this instance.

Our choices are:

1) No grounding of generator

2) Grounding the generator and not bonding to the premises electrode

3) Grounding and bonding, creating a parallel with the grounding conductor in the cord.
 

ceb58

Senior Member
Location
Raeford, NC
I see 'cord and plug connected equipment' to be a type of equipment, which is specified, as opposed to any equipment powered through the receptacles mounted on the generator.

This is why I am looking for a written definition.

My feeling is that in order to be 'cord and plug connected equipment' it has to be designed and manufactured that way. I don't see a breaker as being cord and plug connected equipment.

I agree with you and this topic in the past has gone 100s of posts with no clear resolution.

My $0.02 worth is they are connecting the gen. to the premise wireing via a cord to a panel. I wouldn't consider it cord and plug connected. 250.34 (A) (1) " cord and plug-connected equipment through receptacles mounted on the generator"

What would be the best advice I can offer the guy? I don't think there is a good way to connect a 120 volt generator designed to be used as a portable to a permanently installed entrance panel in this instance.

Our choices are:

1) No grounding of generator

2) Grounding the generator and not bonding to the premises electrode

3) Grounding and bonding, creating a parallel with the grounding conductor in the cord.

IMHO I would ground the gen. and separate the G-N bond in the panel.
You can pretend the gen. is the main panel since it has the first OCP the panel on the building would be a sub panel
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
My $0.02 worth is they are connecting the gen. to the premise wireing via a cord to a panel. I wouldn't consider it cord and plug connected. 250.34 (A) (1) " cord and plug-connected equipment through receptacles mounted on the generator"



IMHO I would ground the gen. and separate the G-N bond in the panel.
You can pretend the gen. is the main panel since it has the first OCP the panel on the building would be a sub panel

OK,

4) Ground generator and configure entrance panel like a sub panel.

Thanks!
 
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