Generator installation questions

[goldstar]

I?m installing 10 and 14 KW Generac generators with whole house transfer switches rated at 200 amps. So far the houses where I?m installing have 150 amp services. The generators come shipped with the neutrals ?floating?. The transfer switch (circuit breaker) is rated at 200 amps. The xfer switch comes shipped with the neutrals bonded to the enclosure but with the ability to remove the bonding jumper and have them float.

Here are my questions :

1. Does the transfer switch (circuit breaker) now become the main circuit breaker for the house or should it act as a molded case disconnect switch only ?
2. Do the neutrals stay bonded to the enclosure in the transfer switch ?
3. Should the grounds be separated in the existing main breaker panel ?
4. Should the connection between the transfer switch and the existing breaker panel be changed to SER cable ?


Here?s my thinking :

1. Since the existing SE cable is rated for 150 amps, the 200 amp disconnect should act as a molded case disconnect switch only. If not, the entire service would have to be upgraded to 200 amps
2. The neutrals should float. They?ll be bonded at the main breaker panel and at the meter enclosure. The existing main breaker panel is less than 5? away (in terms of wire distance)
3. I don?t see why the grounds should be separated seeing as how that?s where the original bonding takes place
4. There?s no need to use SER cable seeing as how this is not considered a sub-panel. Relocating the existing SEU cable to the transfer switch cabinet

Someone please correct me if I'm wrong.

Thanks,

Phil

 

[Len]

whole house

whole house

Before you install did you check peak kw to make sure genset is big enough to meet code?

 

[krisinjersey]

Ummm

Ummm

This whole circuit breaker transfer switch thing is messing with me. I would say if you are supplying a transfer switch that has an MCB,with the utility power and the generator power, that circuit breaker becomes the main. If that's the case, then the secondary supply to the old MCB and panel would need to be either SER or a conduit with your phase conductors, a neutral condutor, and a ground wire. All your bonding needs to go back to the transfer switch too now. And the new grounding for the generator, since it's a SDS, will have to go back there as well. The top half of the service would need to be upgraded to accomodate the 200A Main OCPD. I think you would have to treat the existing main as a sub panel now and seperate the grounds and isolate the neutral.
Most of the transfer switches I've done have been just that service rated transfer switches. There are 150A Generac transfer switches available, and with the volume of headach you see to be addressing here and trying not to blow your costs out of the water, I'd say look into different equipment rather than reinvent the wheel.
Did you have to submit a load calc to the town with the permit/ I'm only asking because I'm in Jersey too and 4 out of the last 5 have had the inspector ask for my calculations for generator sizing.

 

[ceb58]

I?m installing 10 and 14 KW Generac generators with whole house transfer switches rated at 200 amps. So far the houses where I?m installing have 150 amp services. The generators come shipped with the neutrals ?floating?. The transfer switch (circuit breaker) is rated at 200 amps. The xfer switch comes shipped with the neutrals bonded to the enclosure but with the ability to remove the bonding jumper and have them float.

Here are my questions :

1. Does the transfer switch (circuit breaker) now become the main circuit breaker for the house or should it act as a molded case disconnect switch only ?
2. Do the neutrals stay bonded to the enclosure in the transfer switch ?
3. Should the grounds be separated in the existing main breaker panel ?
4. Should the connection between the transfer switch and the existing breaker panel be changed to SER cable ?


Here?s my thinking :

1. Since the existing SE cable is rated for 150 amps, the 200 amp disconnect should act as a molded case disconnect switch only. If not, the entire service would have to be upgraded to 200 amps
2. The neutrals should float. They?ll be bonded at the main breaker panel and at the meter enclosure. The existing main breaker panel is less than 5? away (in terms of wire distance)
3. I don?t see why the grounds should be separated seeing as how that?s where the original bonding takes place
4. There?s no need to use SER cable seeing as how this is not considered a sub-panel. Relocating the existing SEU cable to the transfer switch cabinet

Someone please correct me if I'm wrong.

Thanks,

Phil

The ATS must be service rated,built in utility OCP, or there must be a disconnect/ocp between the meter and ATS.
If the ATS is service rated then the neutral and ground are bonded there.
From the ATS to the mdp you will need 4 wire, 2- ungrounded, 1 grounded and the EGC. The bonding jumper will be removed.
But since you have a 150amp service you have two options. Upgrade to a 200amp service or install a 150amp disconnect/OCP between the meter and ATS. If you add the disconnect then that is where the bonding will take place and ever thing after will be 4 wire.

 

[goldstar]

Before you install did you check peak kw to make sure genset is big enough to meet code?

I did not and I'm not sure why that makes a difference. What section of the CODE do I have to meet ? The genset is not designed to handle the load for the whole house even though the entire house's (potential) load will be transferred during an outage. There is a 65 amp breaker on this 14KW generator. I advise people that they are not going to be able to run 3 air conditioners, 4 hair dryers, the microwave and all the lights in the house at the same time or the genset breaker will trip.

 

[goldstar]

The ATS must be service rated,built in utility OCP, or there must be a disconnect/ocp between the meter and ATS.
If the ATS is service rated then the neutral and ground are bonded there.
From the ATS to the mdp you will need 4 wire, 2- ungrounded, 1 grounded and the EGC. The bonding jumper will be removed.
But since you have a 150amp service you have two options. Upgrade to a 200amp service or install a 150amp disconnect/OCP between the meter and ATS. If you add the disconnect then that is where the bonding will take place and ever thing after will be 4 wire.

For the most part I agree with you and I see your point. However, I got one response from a local inspector and this is what he said would be acceptable to do:

• Leave the 150A SE cable riser in tact
• Remove the load side SE cable and seal off the KO in the bottom of the meter
• Nipple into the side of the meter pan an install 2/0 aluminum (150A if that's what you're using) from the load side of the meter to the line side of the ATS
• Install 150A SER cable from the load side of the ATS to the existing main breaker panel
• Remove the bonding ground screw in the main breaker panel and separate all equip. grounds
• Install a ground bar in the main breaker panel and terminate all grounds there
• The 150A main breaker can remain but becomes a sub-panel (technically speaking).

The 200A breaker in the ATS acts only as a molded case switch and is not designed to protect the SE cable. In all fairness, the only things that are drawing loads are the branch circuits in the existing panel. If there was ever a case where the branch circuit loads came anywhere near 150 amps the existing main breaker would trip. The existing service (as originally constructed) was designed for 150 amps and installing a 200 amp (rated) transfer switch between the meter and the existing panel doesn't make a difference.

I kind of like the idea of replacing the breaker in the transfer switch with a 150 amp breaker but I'm sure I would violate some UL listing or warranty by doing so.

Thank you all for your replies.

BTW, the transfer switch is service rated.

 

[M4gery]

I did not and I'm not sure why that makes a difference. What section of the CODE do I have to meet ? The genset is not designed to handle the load for the whole house even though the entire house's (potential) load will be transferred during an outage. There is a 65 amp breaker on this 14KW generator. I advise people that they are not going to be able to run 3 air conditioners, 4 hair dryers, the microwave and all the lights in the house at the same time or the genset breaker will trip.

702.4 (B) 2 a or b

 

[goldstar]

702.4 (B) 2 a or b

Thanks. BTW it's 702.5(B)2 a or b

 

[ceb58]

For the most part I agree with you and I see your point. However, I got one response from a local inspector and this is what he said would be acceptable to do:

• Leave the 150A SE cable riser in tact
• Remove the load side SE cable and seal off the KO in the bottom of the meter
• Nipple into the side of the meter pan an install 2/0 aluminum (150A if that's what you're using) from the load side of the meter to the line side of the ATS
• Install 150A SER cable from the load side of the ATS to the existing main breaker panel
• Remove the bonding ground screw in the main breaker panel and separate all equip. grounds
• Install a ground bar in the main breaker panel and terminate all grounds there
• The 150A main breaker can remain but becomes a sub-panel (technically speaking).

The 200A breaker in the ATS acts only as a molded case switch and is not designed to protect the SE cable. In all fairness, the only things that are drawing loads are the branch circuits in the existing panel. If there was ever a case where the branch circuit loads came anywhere near 150 amps the existing main breaker would trip. The existing service (as originally constructed) was designed for 150 amps and installing a 200 amp (rated) transfer switch between the meter and the existing panel doesn't make a difference.

I kind of like the idea of replacing the breaker in the transfer switch with a 150 amp breaker but I'm sure I would violate some UL listing or warranty by doing so.

Thank you all for your replies.

BTW, the transfer switch is service rated.

Well I will say I have been in some lively discussions on generator installs with contractors from NJ. It seems your inspectors let a lot of things go. Look at 230.90 (A) I cant see how an inspector would suggest doing what you say.
Your description of the ATS is that it is a whole house switch. As it has been said you are going to have a problem with 702.5 (B)(2) (a)or(b)

 

[M4gery]

Thanks. BTW it's 702.5(B)2 a or b

It changed for 2011.

 

[goldstar]

It changed for 2011.

That makes sense. We're still on 2008. I stand corrected.

 

[M4gery]

That makes sense. We're still on 2008. I stand corrected.

I'm in NJ too but I am studying for the test which is on the 2011 right now :thumbsup:

 

[goldstar]

FYI, this is the answer I got from EGD regarding the use of a 200 amp disconnect on a 150 amp service :

Thank you for contacting Electric Generators Direct.com. In regards to your question, a transfer switch is a simple pass through so the unit would not violate code unless the inspector has an issue with it. We do offer a 150A transfer switch by Generac but you cannot exchange switches from prepackaged units. See link for switch details: http://www.electricgeneratorsdirect.com/Generac-Guardian-RTSD150A3/p7097.html . Thank you, EGD Support

Haven't heard from my local inspector yet but most of the electricians in my contractors association agree that because this is service rated equipment, using a 200 amp rated switch on a 150 amp service is acceptable and no other changes need to be made (i.e. SER cable, separating grounds in the existing panel, upgrading to 200 amp service). I'll post more info when I find out more.

 

[tekelec]

IMO the service rated transfer switch now becomes your main disconnect, requiring proper grounding and bonding. The existing main breaker panel now becomes a sub panel and a 4 wire wiring method needs to be installed, and you will have to separate grounds and neutrals, isolating neutral bar from panel box. If using a 200amp service rated transfer switch then service would have to be sized accordingly. I also am usually requested to submit a basic drawing. load calculations, and /or load shedding.

 

[goldstar]

IMO the service rated transfer switch now becomes your main disconnect, requiring proper grounding and bonding. The existing main breaker panel now becomes a sub panel and a 4 wire wiring method needs to be installed, and you will have to separate grounds and neutrals, isolating neutral bar from panel box. If using a 200amp service rated transfer switch then service would have to be sized accordingly. I also am usually requested to submit a basic drawing. load calculations, and /or load shedding.

Thank you for your opinion and I can appreciate how you might feel that way. The problem is that Suzanne Borek is out of the DCA office on sick leave, leaving inspectors in NJ with the ability to run rampant with their own interpretations of how the NEC applies to this situation. I can't tell you how many inspectors I've spoken to so far that have differing opinions. I intend to install these gen-sets with whatever the local AHJ's require, short of upgrading the entire service to 200 amps. This xfer switch is service rated equipment. It's a switch and not the main over-current protection. It has a higher current rating than the existing service and, in all probability, will not trip before the existing 150A main circuit breaker.

BTW, if you look at 702.5(B)(2) you have to comply with (a) OR (b). The xfer switch comes with Nexus load shedding so I would not have to provide the AHJ with connected load information (the way I read the code)

 

[JES2727]

This xfer switch is service rated equipment. It's a switch and not the main over-current protection.

Does the ATS have over-current protection? If the ATS is service rated and has a circuit breaker why would you not consider it the main over-current protection?
IMO, if the ATS ( & 200A CB) is on the line side of the existing 150A service then the ATS CB becomes your main and the 150A panel becomes a subpanel. A four wire feeder is required to the 150A panel and the neutrals must be separated from the grounds. This is the way I do it.

 

[ceb58]

IMO the service rated transfer switch now becomes your main disconnect, requiring proper grounding and bonding. The existing main breaker panel now becomes a sub panel and a 4 wire wiring method needs to be installed, and you will have to separate grounds and neutrals, isolating neutral bar from panel box. If using a 200amp service rated transfer switch then service would have to be sized accordingly. I also am usually requested to submit a basic drawing. load calculations, and /or load shedding.

Does the ATS have over-current protection? If the ATS is service rated and has a circuit breaker why would you not consider it the main over-current protection?
IMO, if the ATS ( & 200A CB) is on the line side of the existing 150A service then the ATS CB becomes your main and the 150A panel becomes a subpanel. A four wire feeder is required to the 150A panel and the neutrals must be separated from the grounds. This is the way I do it.

I cannot understand why you think there is going to be a magic answer. Your question has been answered more than once. Read 230.90 (A) and then tell us how you or any one else can say the 200amp breaker doesn't matter and you don't have to comply. What if this were not a transfer switch? What if it was a outdoor panel with a 200 amp main breaker would you still say that the 200 amp, being the first disco/ocp in the system, didn't count?

 

[goldstar]

I cannot understand why you think there is going to be a magic answer. Your question has been answered more than once. Read 230.90 (A) and then tell us how you or any one else can say the 200amp breaker doesn't matter and you don't have to comply. What if this were not a transfer switch? What if it was a outdoor panel with a 200 amp main breaker would you still say that the 200 amp, being the first disco/ocp in the system, didn't count?

I'm not looking for a magic answer at all and yes, there have been several answers here and I appreciate them all. In all fairness, yours may be the most correct answer. However, they're all just opinions and while many of them make sense they are just that - opinions. Even if Mike Holt himself posted an answer here, while I would hold his opinion in the highest regard, it would still only be an opiniion and his interpretation of the code as it applies to this situation.

Now, I'm sitting here asking myself several questions like :

• Why would this company only offer pre-packaged units with only 100 and 200 amp xfer switches ?

• Do they believe that homeowners across the country have only 100 and 200 amp services ?

• Would all homeowners with 150 amp services have to upgrade to 200 amps in order to have one of these installed and meet code ?

• If that were the case wouldn't it make sense for this company to offer 150 amp xfer switches to increase sales ?

Can you imagine the chaos if every inspector in every municipality in every state had their own opinion of how this should be interpreted or for that matter, based his decision on the best answers received here in the forum ? The best I can hope for with this is that an official of the state makes a decision as to how this should be done so that every electrician in our state can install these units to the same standard and an inspector would not be able to fail a job after it's installed to that standard. If they tell me that upgrading to a 200 amp service is the only way to do this, then so be it.

 

[ceb58]

• Why would this company only offer pre-packaged units with only 100 and 200 amp xfer switches ?

Production. In your case a 150amp service, for today, is an odd size. They use the 100 amp for people who cannot or do not want to go whole house. Set the 100 feed it from the main panel to a sub panel with selected loads. The 200, which would be the most common size service, would be for a whole house or a sub panel in a larger service home.

• Would all homeowners with 150 amp services have to upgrade to 200 amps in order to have one of these installed and meet code ?

No, there again a sub panel with selected loads can be used. Or a 150amp disco/ocp can be installed between the meter and ATS. In your OP you state you are installing a 14 kw and a 10kw. What is the calculated load on the homes?

 

[bradleyelectric]

Why would this company only offer pre-packaged units with only 100 and 200 amp xfer switches ?

They also offer a 400.

Just because you don't like it doesn't mean it isn't right.