Thread: Emerg Gen - Service equipment or not?

This is a home with an emergency generator and auto transfer switch for total house back up.
This was obviously added after the hoiuse was built and installed between the "old" main service panel and the service conductor.

The transfer switch has a 200A main service disconnect and connects the distribution panel to the power service with a four conductor cable.


I have a bunch of questions and could use some schooling, as it doen't look correct to me.


1. Is the emerg gen transfer switch NOW considered the Main Service equipment?

2. The ground rod and bonding connections are at the "old" main service panel. Should it be moved to the emergency generator panel if it is now considered main service equipment?

3. Does the "old" main service panel have to be re-wired with isolated ground and neutral bars - treated like any non-service equipment panel?

4. In the picture you can see the feed from the generator to the transfer switch. It is smaller than the main service conductors and not rated for 200 amps, Should I see an additional breaker at the Generator to protect this wire?

5. Does the generator require a separate isolated ground rod located at the generator?

What would you report to the client?

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Originally Posted by Ken Amelin

This is a home with an emergency generator and auto transfer switch for total house back up.
This was obviously added after the hoiuse was built and installed between the "old" main service panel and the service conductor.

The transfer switch has a 200A main service disconnect and connects the distribution panel to the power service with a four conductor cable.


I have a bunch of questions and could use some schooling, as it doen't look correct to me.


1. Is the emerg gen transfer switch NOW considered the Main Service equipment?

2. The ground rod and bonding connections are at the "old" main service panel. Should it be moved to the emergency generator panel if it is now considered main service equipment?

3. Does the "old" main service panel have to be re-wired with isolated ground and neutral bars - treated like any non-service equipment panel?

4. In the picture you can see the feed from the generator to the transfer switch. It is smaller than the main service conductors and not rated for 200 amps, Should I see an additional breaker at the Generator to protect this wire?

5. Does the generator require a separate isolated ground rod located at the generator?

What would you report to the client?

Hi Ken,
In regards to your questions.
1. Yes.
2. Yes.
3. Yes.
4. Yes. There is usually a black plastic cover on the side of the generator and behind it is the breaker.
5. No. The generator is not considered a separately derived system.

Inform the client that in your opinion there are the electrical irregularities you indicated and that repairs are recommended by a qualified electrician. Additionally, I would let them know that running the generator, the condition of the generator, the operating condition and its ability to perform if needed is beyond the scope of the inspection.

Hope this helps.

Corey

Corey - is there something specific about this model of ATS on which you are basing your answers? It seems to me that the answers to Ken's questions depend on whether the neutral is bonded inside the ATS, and my assumption would have been that it wasn't. That would make the answers to Ken's first three questions a "no" rather than a "yes".

For question 5, I can't see a supplemental ground rod hurting anything, especially if the generator is located remote from the house. We see that sometimes where large (loud) generators are installed outside large houses. A more important question, related to question 5, is whether the main bonding jumper should be connnected inside the generator. If the ATS switches the neutral, then it should, because that bonding jumper becomes part of the fault current path during operation of the generator (and the generator would then be a separately derived system). If the ATS doesn't switch the neutral, then the generator bonding jumper should be removed, and it isn't a SDS.

One of the photos shows a switch on the cover of the ATS, and it is labeled "utility disconnect." I don't think that is really a service disconnect. It could just be an override that disconnects all power to the subpanel. Since shutting off the (original) service disconnect would simply cause the generator to start, there needs to be some other means of truly shutting off all sources of power, and that switch would be it. We did one of these a few years ago and the switch was electronic, rather than mechanical, so our switch was a red EPO button.

There should be an owner's manual for these things, and often a maintenance contract. The ATS should start the generator periodically (without switching over to it) to keep it lubricated. There should be signage at the service indicating another source of on-site power.

Douglas Hansen
Code Check- Help With Building Codes

I would put my money on the Generac generator in question IS NOT a separately derived syatem.These home generators are arranged for the ease of installation.
I have seen tons of those generac systems and have yet to see one that switches the neutral.

If the transfer switch is in between the electric meter and the panel , then the Transfer switch becomes the Service disconnect. Thus the "old" service panel would now be treated as a subpanel.
The grounds and neutrals shall be separated.
The grounding electrode conductors from the ground rod, incoming water shall be moved over to the transfer switch. The thing to keep in mind is when the grounding electrodes are extended to the transfer switch they can be spliced BUT the splice must be irreversible. In other words it must be crimped or exothermic welded. No split bolts /wirenuts allowed on this splice.
There is a overcurrent device at the generator that is used to determine the size of the conductors between the generator and the transfer switch.

As far as a ground rod at the generator you should look in the generator manual. Some generators specifically tell you not to install one at the generator. If you can not find the manual , get the model number of the generator and go to the generac website. You can look up the installation instructions / manual there.
This will also tell you if it is a separate derived system.
There are also restrictions on the location of the generator. I do believe the the IRC calls for the generator to be 10' from any window or door.

Originally Posted by jack davenport

I would put my money on the Generac generator in question IS NOT a separately derived syatem.These home generators are arranged for the ease of installation.
I have seen tons of those generac systems and have yet to see one that switches the neutral.

Agree with the above.

If the transfer switch is in between the electric meter and the panel , then the Transfer switch becomes the Service disconnect.

Disagree with the above - the transfer switch is not the disconnect and thus is not the "service equipment", all the transfer switch does is ... well ... "transfer" ... the transfer switch "transfers" the supply connection from one supply (utility power, for example) to another supply (generator power, for example) but does not "disconnect" anything - power is still "connected", the only thing which changes was the source of that power.

Service equipment is still needed and typically that service disconnect is before the transfer switch, i.e., the utility power service equipment disconnect when on utility power and the service disconnect which is typically built into the generator when on generator power, at least that was how the whole house optional standby generator was made and installed when I bought one and installed in on the house we had in South Florida in 2004-5.

The generator comes with a main breaker which shuts off power from the generator, even though the generator is still operating and running. There were also two duplex GFCI receptacles built into the Generac generator I had.

Very few, if any, generators for whole house use will switch the neutral in the transfer switch, thus it is simply a secondary source for power which replaces utility power when the utility power goes off (presuming that the generator is connected to automatically start and that the transfer switch is automatic acting). A manual transfer switch would be the same except that the transfer switch would need to be manually operated and the generator manually started (I would not want to automatically start the generator with a manual transfer switch, and there really is no need to have the generator start automatically when the transfer switch is a manual type).

Jerry is right.

The existing service is still the service. It's still the first place where you can disconnect power from the utility. The fact that you have a second place further downstream that also could disconnect the power doesn't change the location of the service any more than installing a main breaker in the subpanel would have changed it. The requirements that go with something being the service include having the grounding electrode conductor connection to the neutral no further downstream than the service enclosure. The feeder from the service to the ATS is still a feeder, not an extension of the service entrance conductors.

What makes something a separately derived system is a new neutral, and we all seem to agree that is unlikely here. Unless the neutral is switched, the bonding jumper in the generator must be removed or you have a parallel path. Current that should be going from the neutral in the ATS back to the service could also travel on the equipment grounding conductor from the generator back through the ATS and to the service. Nothing was said here about the type of generator, though I think most of these ship with the bonding jumper in place.

Douglas Hansen
www.codecheck.com

Originally Posted by Douglas Hansen

Corey - is there something specific about this model of ATS on which you are basing your answers? It seems to me that the answers to Ken's questions depend on whether the neutral is bonded inside the ATS, and my assumption would have been that it wasn't. That would make the answers to Ken's first three questions a "no" rather than a "yes".

For question 5, I can't see a supplemental ground rod hurting anything, especially if the generator is located remote from the house. We see that sometimes where large (loud) generators are installed outside large houses. A more important question, related to question 5, is whether the main bonding jumper should be connnected inside the generator. If the ATS switches the neutral, then it should, because that bonding jumper becomes part of the fault current path during operation of the generator (and the generator would then be a separately derived system). If the ATS doesn't switch the neutral, then the generator bonding jumper should be removed, and it isn't a SDS.

One of the photos shows a switch on the cover of the ATS, and it is labeled "utility disconnect." I don't think that is really a service disconnect. It could just be an override that disconnects all power to the subpanel. Since shutting off the (original) service disconnect would simply cause the generator to start, there needs to be some other means of truly shutting off all sources of power, and that switch would be it. We did one of these a few years ago and the switch was electronic, rather than mechanical, so our switch was a red EPO button.

There should be an owner's manual for these things, and often a maintenance contract. The ATS should start the generator periodically (without switching over to it) to keep it lubricated. There should be signage at the service indicating another source of on-site power.

Douglas Hansen
Code Check- Help With Building Codes

Hello Doug,

Based on how the OP worded his question indicating that the ATS had a service disconnect I took him on his word that he already determined that this is service entrance equipment and question 2 also adressed the issue. Question 3 indicated that he is aware that the old panel is essentially now a sub-panel and therefore bonding needs to take place in the ATS service equipment.

I am familiar with the Generac line and that ATS looks like the ones that come with the neutral bonded. There is label or it is in the instructions that tell you to remove the bond if not being used as service entance equipment.

I agree that if the ATS breaker is turned off the genny will start. Locally, the breaker on the genny (even the gas valve) is considered an acceptable way to turn it all off without the need for an additonal breaker or EPO.

An installer should leave the manuals with the home owner. Most Generac's that I see actually have two manuals. Installer manual and owners' manual.

I agree there should be a sign indicating another power source at the service. If I am not misaken, the sign should say where the genny is located although it is most common just to see some sort of warning label that says genny present.

Sincerely,

Corey

Originally Posted by Jerry Peck

Agree with the above.



Disagree with the above - the transfer switch is not the disconnect and thus is not the "service equipment", all the transfer switch does is ... well ... "transfer" ... the transfer switch "transfers" the supply connection from one supply (utility power, for example) to another supply (generator power, for example) but does not "disconnect" anything - power is still "connected", the only thing which changes was the source of that power.

Service equipment is still needed and typically that service disconnect is before the transfer switch, i.e., the utility power service equipment disconnect when on utility power and the service disconnect which is typically built into the generator when on generator power, at least that was how the whole house optional standby generator was made and installed when I bought one and installed in on the house we had in South Florida in 2004-5.

The generator comes with a main breaker which shuts off power from the generator, even though the generator is still operating and running. There were also two duplex GFCI receptacles built into the Generac generator I had.

Sorry but the transfer switch located between the electric meter and the panel does become the service. We all know that the service equipment is the first disconnecting means past the electric meter. The transfer switch in question is located between the meter and the panel. The breaker in the transfer switch is label service disconnect.
The genrac transfer switches are labeled "suitable for use as service equipment" as per the NEC.
They are now rated to be used as service equipment and are designed that way so one does not need to install another switch as you describe in front of it.

Jack, aren't you assuming that the panel shown in the original post was the service? I think we are operating under different sets of assumptions here. I have taken the original post to mean that there is another disconnect upstream from this transfer switch, that is what Ken called the "old" main service panel. The transfer switch is between the two original panels, and not the first place at which power can be disconnected from the building. I would agree with you if there wasn't anything ahead of it that turns off the power, but going back to Ken's original post that doesn't seem to be the case.

Douglas Hansen
www.codecheck.com

I believe you will find a breaker on the generator, the last 2 I looked at had one. But, it looks like the generator might be undersized. Under NEC 702.5 generators need to be sized for the full load where automatic transfer equipment is used.

The gensets I've installed as an E Contractor in both residential and commercial are Many. I also was factory trained in diagnose/installation. I've inspected hundreds of gensets as an AHJ.

I'll just list some facts and apologize in advance for others whom have stated;
Most home-style gensets are not seperately derived as the switch does not disconnect the grounded conductor, it is usually 'solid'.
I've tried for years to get Kohler to stop bonding their neutral inside their generator and had to continually have the contractor come back out and remove/field isolate it inside. sheeesh!

If the transfer switch does contain service conductors, than it is service equipment regardless if there is a main disconnect in the enclousure. However, if the transfer switch does transfer power from the gen to the panel, then it most certainly has to 'disconnect' the service conductors to accomplish this act. Therefore, this type of transfer panel is the main service disconnect (most also have a means to do so manually) and all the rules for service equipment apply.
Note that whole service transfer panels are required to be 'service rated' and to meet this requirement almost all manf. have installed main breakers inside.

Originally Posted by Douglas Hansen

Jack, aren't you assuming that the panel shown in the original post was the service? I think we are operating under different sets of assumptions here. I have taken the original post to mean that there is another disconnect upstream from this transfer switch, that is what Ken called the "old" main service panel. The transfer switch is between the two original panels, and not the first place at which power can be disconnected from the building. I would agree with you if there wasn't anything ahead of it that turns off the power, but going back to Ken's original post that doesn't seem to be the case.

Douglas Hansen
www.codecheck.com

Doug-
Yes I am assuming that the panel shown was the original service panel. I base this on the way Ken posted his questions. I take it that when Ken refers to the "old" main service... with old in quotation marks , he is now referring to the transfer switch as the "new" service disconnecting means. From what I can see when I blow up the picture I see what looks like a 3 conductor SEU feeding the transfer switch, and a 4 conductor SER going to the panel, and a 4 conductor SER going to the generator.
That 3 conductor cable I take is coming from the electric meter.
Only Ken can tells us for sure.

702.5 in the 2008 NEC is now 702.4 in the 2011 NEC

702.4(B)
System Capacity . The calculations of load on the standby source shall be made in accordance with article 220 or by another approved method.

702.4 (2)
Automatic Transfer Equipment
Where automatic transfer equipment is used, an optional standby system shall comply with 2(a) OR 2(b)

2(a) - Full Load. The standby source shall be capable of supplying full load that is transfered by the auotmatic transfer equipment

2(b)- Load management. Where a system is employed that will automatically manage the connnected load, the standby source shall have a capacity sufficient to supply the maximum load that will be connected by the load mamnagement system.

So, 702.4(B) tells us we must perform a load calculation on the dwelling based on article 220.
702.4 (2)(a) Tells us We then size the generator based on this load calculation

There are no load management modules pictured so I assume they are not presently being utilized,so that takes 702.4(2)(b) off the table


So without having the load calculation and the generator size it is hard to determine if this generator is undersized.

You will find that most houses do not have that large of an load. They have the potential of a large load, but the generator is sized based on the load calculation not the potential load.

Originally Posted by jack davenport

Doug-
Yes I am assuming that the panel shown was the original service panel. I base this on the way Ken posted his questions. I take it that when Ken refers to the "old" main service... with old in quotation marks , he is now referring to the transfer switch as the "new" service disconnecting means. From what I can see when I blow up the picture I see what looks like a 3 conductor SEU feeding the transfer switch, and a 4 conductor SER going to the panel, and a 4 conductor SER going to the generator.
That 3 conductor cable I take is coming from the electric meter.
Only Ken can tells us for sure.

And I have been assuming there was a disconnect upstream from the ATS, and that it was supplied by a feeder, not service conductors. Looking closely at the photo, it DOES look like SEU from the utility to the ATS, which would indeed make your position correct, along with Corey, Bob, and others.

My West Coast bias plays into the assumption I've been making. All our residential service disconnects are outdoors, and I'm slow to realize that the service is often in a basement in other parts of the country.

Douglas Hansen
www.codecheck.com

Originally Posted by Douglas Hansen

Corey - is there something specific about this model of ATS on which you are basing your answers? It seems to me that the answers to Ken's questions depend on whether the neutral is bonded inside the ATS, and my assumption would have been that it wasn't. That would make the answers to Ken's first three questions a "no" rather than a "yes".

For question 5, I can't see a supplemental ground rod hurting anything, especially if the generator is located remote from the house. We see that sometimes where large (loud) generators are installed outside large houses. A more important question, related to question 5, is whether the main bonding jumper should be connnected inside the generator. If the ATS switches the neutral, then it should, because that bonding jumper becomes part of the fault current path during operation of the generator (and the generator would then be a separately derived system). If the ATS doesn't switch the neutral, then the generator bonding jumper should be removed, and it isn't a SDS.

One of the photos shows a switch on the cover of the ATS, and it is labeled "utility disconnect." I don't think that is really a service disconnect. It could just be an override that disconnects all power to the subpanel. Since shutting off the (original) service disconnect would simply cause the generator to start, there needs to be some other means of truly shutting off all sources of power, and that switch would be it. We did one of these a few years ago and the switch was electronic, rather than mechanical, so our switch was a red EPO button.

There should be an owner's manual for these things, and often a maintenance contract. The ATS should start the generator periodically (without switching over to it) to keep it lubricated. There should be signage at the service indicating another source of on-site power.

Douglas Hansen
Code Check- Help With Building Codes

Yes there is a BOND from the Neutral bus to the inclosure ....in the 200 amp Generac ATS ...if the ground bar has the proper ground then the neutral is grounded, same as it would be in the Meter pan

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