Need Details Clarified on Standby Gen W/ATS Installation

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  #1  
Old 08-24-13, 09:51 PM
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Question Need Details Clarified on Standby Gen W/ATS Installation

Long time user/lurker, first time poster. Thanks to all the knowledgeable people on here who share their skills to help others.

Until now I have been able to find answers to everything I needed by searching, but for my current project I still have unanswered questions.

I am preparing to install a Kohler 14RESA generator with a service entrance rated 200A model RXT automatic transfer switch. This switch has a 200A main breaker/service disconnect built in. It only switches off the normal (power company) feeds.

Currently my main panel is mounted back to back with the meter base. I plan to mount the transfer switch next to the meter base. It is a NEMA 3R box. I will remove the existing wires from the meter to the panel main, and run new wires from the meter to the automatic transfer switch (ATS) normal lugs. Of course the generator power will be wired to the ATS emergency lugs. Then I will make a new hole through the wall into the main panel (with 2" conduit) for the wires from the ATS load lugs to the main panel breaker. This brings up my first question... is it necessary to plug the existing 2" conduit that connects the meter base with the main panel? If so, what is an acceptable way to block that opening?

Wired the way I have described, my understanding is that my main panel becomes a sub panel. The ATS comes with the neutral and ground bars bonded, and the ground bar bonded to the box. I know to run 4 wires from there to the main panel (now a sub panel). I know to separate the grounds and neutrals in the main panel. This brings up the second question. There are three neutral/ground bus bars in that panel, all mounted on the same piece of bare metal, insulated from the box. I do not see a panel bond screw, or any other way that the neutral/ground bus is bonded to the box, so this would serve as a neutral bar, just as it is. I also do not see any pre drilled holes in the back wall of the box to mount a ground bus bar. The question: Is there any reason I should not remove one of those bus bars (they are all mounted to a piece of bare aluminum with two screws each), drill and tap some holes in the back wall of the box, scrape the paint off where the bus bar will be touching the box, and mount one for a ground bar? Alternatively, I can buy a ground bar kit, but it is just a bus bar and two screws, and I already have those. The reason for the question is, any sub panel I have installed before either had two bars that could be separated, or was pre drilled for a grounding bus bar kit.

Sorry for such a long post, but I wanted to give as much info as possible to avoid you guys having to ask clarifying questions. But if I haven't made myself clear, or any of my plans are questionable, please let me know.

Thanks in advance, John
 
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  #2  
Old 08-25-13, 04:34 AM
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You provided enough information however, if you could post some pictures of your panel that would be great.

Both questions could be easier to answer.

Thanks
 
  #3  
Old 08-25-13, 10:40 AM
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Bus Bars

These are the bus bars in my panel. It is a Square D model QOB40MW200-2

As for the conduit from the meter base, it is hidden by wires, can't get a picture of it, can barely see it. But the question is basic: Does code allow an unused, open conduit? I thought it might matter that it is so short (just through a stud wall with brick siding), and it leads from a protected area (the main panel) to an unprotected area (the meter base) By unprotected I mean no overcurrent device on any of the wires in the meter base.
Thanks, John
 
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Old 08-25-13, 12:03 PM
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The question: Is there any reason I should not remove one of those bus bars (they are all mounted to a piece of bare aluminum with two screws each), drill and tap some holes in the back wall of the box, scrape the paint off where the bus bar will be touching the box, and mount one for a ground bar?
No, I don't think I'd remove a part of the neutral bus to become a ground bar. You appear to have an older Square D loadcenter possibly from the early '80s. I am not sure if the box bonding screws were green at that time, but I don't think they were. It is possible that the bonding screw was never installed. You may not have pre-drilled holes for a ground bar, have you checked the label inside the panel box for information on that? Not inside the cover/door, but inside the panel box. That label should also give you the location for the bonding screw. It should be easy enough to drill holes for a Square D ground bar.

I see a black wire in the neutral bar, looks like a #12. What is that for? To fill the conduit nipple between the panel and the meter base, I'd just use duct seal.
 
  #5  
Old 08-25-13, 01:06 PM
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Thanks CasualJoe, you got me to look at the left side of the box for a label. I had only saw the one on the right side, which only gave the part number. On the left side label is listed a PK23GTA or PK23GTA-L ground bar. It does not show where to mount it, but, as you suggested, it does show the location for a bonding screw. There is a hole behind that black wire you asked about, and it is empty and I can see a threaded hole behind it. So that bus is good to go like it is for the neutral bus. While power is out of the box I will check with a meter for continuity between that group of bus bars and the box, to make sure it is isolated. I will purchase the PK23GTA kit and screw it to the back of the box for the ground bus.

The black wire is part of a reverse wired 20A 120V circuit. The white wire goes to the circuit breaker. Who knows why??? It is surely part of the original house wiring as it feeds the refrigerator and outlets above the kitchen counter, including one with a GFCI. The GFCI test and reset buttons work. I would correct the wiring, but that black wire is too short to reach the breaker. I had planned to tape them with the correct colors while working in the panel. Or, should I extend the black wire with a wire nut and get the colors right?

I will use your duct seal suggestion on the conduit.

Thanks for the help.
 
  #6  
Old 08-25-13, 03:13 PM
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The white wire goes to the circuit breaker. Who knows why???
Exactly..... it needs to be corrected at both ends. You can add the same color on in the panel with a wire nut to extend it to reach where it needs to go.

Just a side note here..... I'm installing a lot of generators, as are a number of others, and the installations are turning into a free for all. The electrical inspectors as well as town officials here in NJ are demanding permits and load calculations. A 14k generator on a 200amp service would raise a concern here. Normally a 20k on a 200amp service.

You need to make sure when you are not home and the genny starts and transfers that its safety breaker won't trip due to too much load.
 
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Old 08-25-13, 03:48 PM
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You need to make sure when you are not home and the genny starts and transfers that its safety breaker won't trip due to too much load.
Good point, PJ. The NEC requires that when an automatic transfer switch is used, the generator must carry the entire calculated load......OR.....the transfer switch must have load shed capability to drop excess load to prevent the generator's output breaker from tripping.
 
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Old 08-25-13, 04:00 PM
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While power is out of the box I will check with a meter for continuity between that group of bus bars and the box, to make sure it is isolated.
I see a problem doing this test before you install the transfer switch. If your neutral is properly grounded and the meter socket is also properly grounded, you'll probably show continuity between the neutral bus and the panel box. I think you'll be reading the ground through the conduit nipple to the panel when in fact, there is no direct connection between the neutral bus and the panel box. I believe you'd have to disconnect the meter socket to panel neutral connection and any grounding conductors between the neutral bus, ground rod and/or water service to get a meaningful reading. If you have verified that the bonding screw was never installed, I think I would accept that as evidence the neutral bar is not connected to the panel box.

I will purchase the PK23GTA kit and screw it to the back of the box for the ground bus.
The ground bar kit should come with attachment screws, but they won't be tapping screws. You'll need to drill the proper size holes and tap threads for these screws. Do not use Tek screws, that would be a code violation.
 
  #9  
Old 08-25-13, 05:04 PM
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C

PJ, thanks for the comments. Based on everything I have seen since we moved in here, I think it would be a good idea to test all my outlets for proper wiring and grounds.

Already on my to do list, while I am wiring the transfer switch: Put NM clamps on all the branch circuit wires. Right now all the wires go out through bare, rough edged knock-out holes. If that make you electricians cringe...When we moved here there was a well, with an above ground pump. The well casing was rusted bad, and the water would not clear up, the house was on county water, so I decided to eliminate the well. Also, I was going to do some grading in the back yard to correct drainage problems, and knew I would be going deep enough to hit the feeder to the well. I could not kill power to the well. I have a shop with its own service and meter. I turned off the main breaker in the house and the shop, the well house was still hot! I finally found the feeder wire to the well hooked directly to the meter base. It was on the metered side, but no overcurrent protection on about 100' of direct burial wire. In the well house it was hooked to a beat-up fuse box (the cover would not close), and from there it fed a small storage shed about 20' away. The shed had a two circuit fuse box, again with wires fed through raw knock out holes. Three prong, grounded receptacles were wired with two wire cable, but that was OK, they had grounded it with a jumper from the neutral to the ground screw!! And one of these receptacles was on an outside wall. Your hair standing on end yet?? If not go look in my attic. An open junction box, again with NM wires run through knock outs with no clamps or bushings. Other wires are joined in the box, but do not go through a knock out. The hot and neutral are twisted together and taped, and the grounds are twisted together in what looks like kind of wire sculpture. But enough about all this other "stuff" I have to get fixed.

About the generator load and unattended start up. I have replaced the electric water heater with gas. I have replaced the A/C / Heat Pump (that had supplemental heat strips) with a A/C / Heat Pump with gas supplemental heat. It is a 3T unit with 16.7 RLA and 82 LRA. Min. Circuit Ampacity is 28.6, Max Overcurrent Protective Device is 40A It is on a 40A breaker. The electric dryer stays off after a power interruption, as does the electric stove. Top burners will NOT come back on unless they are turned off, then back on. The oven (digital control) just flashes "PF" (power failure). The wife wants a gas stove, so that WILL be replaced. The air conditioner/heat pump will not restart for 5 min. after a power failure. As I stated before, there is no well pump. The only motor load for the generator to restart on change over is the fridge and a freezer, if they happen to be on. The generator is rated at 58.3A on LP gas. Peak motor starting kVA @240V is 35. The Kohler "brag sheet" states, "The 14KW generator can easily start and run a 5T air conditioner."

Have I missed anything?? I replaced the water heater and heat strips to be able to use a smaller generator. Not just for the price difference, because there is not a lot of difference between the 14 and the 20, but fuel consumption is quite a bit different. At full load, the 14 uses 81 CFH, the 20 uses 136, and it uses 82 CFH at 50% load. So, even half loaded, the 20 would use a little more fuel than the 14 at full load.
If you guys know anything else I should consider, I am all ears.
Thanks, John
 
  #10  
Old 08-25-13, 07:43 PM
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I think you'll be reading the ground through the conduit nipple to the panel

Joe, I see your point. Is that connection a problem? Should I remove the nipple from between the boxes? If I don't remove it, and I mount a new bus bar, have I really separated the grounds from the neutrals? If there is continuity from the neutral bar to the box, and therefore to the new ground bar, they are all still electrically connected, so what is the point?

You'll need to drill the proper size holes and tap threads for these screws. Do not use Tek screws, that would be a code violation.
That was my intention. I will see what size screw comes with the bar and drill and tap for that screw.
 
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Old 08-26-13, 07:52 AM
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Joe, I see your point. Is that connection a problem? Should I remove the nipple from between the boxes? If I don't remove it, and I mount a new bus bar, have I really separated the grounds from the neutrals? If there is continuity from the neutral bar to the box, and therefore to the new ground bar, they are all still electrically connected, so what is the point?
No, you shouldn't have to remove the conduit nipple between panel and meter socket. In the end, both panel box and meter socket box are supposed to be grounded anyway.

Technically, the NEC says your full calculated load needs to be backed up. In your area, I seriously doubt you'll find an inspector who will ask to see the calculated load. Are there even any inspections there? Any permits required? I suspect you'll be OK with the 14 KW generator, but in the end you are the one who has to live with it. From your post, I assume you are fueling the generator with LP and not natural gas. The natural gas fueled KW rating is only 50 amps.
 
  #12  
Old 08-26-13, 08:35 AM
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Joe, I realized right after I posted about the continuity between the boxes and the bus bars that it is not about that they are at the same potential, but the path back to the source.

You are right, I am out in the county, no permit or inspection required. And, yes, LP is the fuel. I have a new gas line and regulator in and waiting, and the gen and ATS will be here this week. I just finished a gravel pad yesterday.

Thanks for all your help and advice, John
 
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Old 08-26-13, 09:38 AM
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Good luck with your project and finding/fixing all those other issues you have found.
 
  #14  
Old 08-27-13, 10:00 PM
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Confirm wire sizes

I want to get expert confirmation on my wire and conduit sizes for this job. This 14Kw generator is rated at 58.3A on LP gas (what I am using) and has a 70A output breaker. I am planning to wire from the gen. to the transfer switch with three #4 copper (THHN/THWN). This is what the dealer recommended. Should I use a # 8 or #6 ground? In the same conduit will be a 120V circuit (three #12s), fed from a GFCI breaker in the main panel to power the battery charger in the gen. With three #4s, one #8 or #6 and three #12s, what is the correct size PVC conduit? Distance is about 20' or less.

Also, for the 200A service wires, I will be using 2/0 copper. What is the proper size neutral? I plan on #4 copper for the ground.

BTW, I picked up the ATS, gen and pad today and got it set in place. Ready for wire and gas.

Thanks again, John
 

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  #15  
Old 08-28-13, 08:28 AM
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Should I use a # 8 or #6 ground?
You could probably get by with #10 but #8 would be better.

With three #4s, one #8 or #6 and three #12s, what is the correct size PVC conduit?
1" minimum. I might run 1-1/4" or 1-1/2" to make the pull easier. In fact, I would run one 1" and one 3/4" conduit, to keep the gen feed and the GFCI feed separate.

for the 200A service wires, I will be using 2/0 copper. What is the proper size neutral?
2/0

I plan on #4 copper for the ground.
#6 copper is large enough.
 
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Old 08-28-13, 09:59 AM
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Thanks. I was kinda planning on 1 1/4" for the power because I have a few fittings in my left overs I can use. And I hate a tight pull. As for separating the gen and the GFCI feeds, is that necessary? I already have to run a separate 1/2" for the control wiring and there is only room for two conduits at the generator. Kohler supplies a template for drilling those holes, and it has only two, one labeled for power, one for control. They also specify the two different power circuits, but only have provisions for one entry, so that leads me to believe they intend them to share the same conduit. Also, the terminals for both circuits are side by side on the same terminal block.
Thanks, John
 
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Old 08-28-13, 11:50 AM
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As for separating the gen and the GFCI feeds, is that necessary? I already have to run a separate 1/2" for the control wiring and there is only room for two conduits at the generator
I don't believe you have to use separate conduits for the power output and GFCI feed, but I like to if possible (you may not be able to). I assume the GFCI feed will be for a service receptacle and battery charger, is that correct? I also assume the control wiring is DC voltage, the same voltage as the battery, probably 12 volt, is that correct? These small residential generators from different manufacturers require studying the schematics carefully, they aren't all the same and I am not familiar with the small Kohler units.
 
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Old 08-28-13, 01:28 PM
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I don't believe you have to use separate conduits for the power output and GFCI feed, but I like to if possible (you may not be able to).
There is just not room on the small (about 5"W X 6"H) plate provided for conduit and gas inlet. Well, there is room at the top left, directly above the gas inlet, but the wires would then enter above the gas valve and not in the area behind the wiring cover. I am going with one 1 1/4" conduit.

I assume the GFCI feed will be for a service receptacle and battery charger, is that correct?
Yes.

I also assume the control wiring is DC voltage, the same voltage as the battery, probably 12 volt, is that correct?
I assume 12V as well. The wiring diagram doesn't call out the voltage on any of the control wires. It does note the starting and charging as 12V, so you would think they would use the same voltage for the control system as well. Battery charger is built into the control board. All the install manual calls it is "low voltage communication leads. They specify using Belden #9402 or equivalent, 20AWG shielded, twisted pair cable. That is a two pair cable with each pair separately shielded. I will also be running a Cat5E cable in that same conduit, for remote monitoring.

Just finished the gas plumbing... NO leaks!!! Yea! Moving on now to running conduit. Thanks to all you guys who have helped on here I have a clear plan of what to run and where.
 
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Old 08-28-13, 06:43 PM
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Communication wiring has changed dramatically in the last 10 years. Used to be all you needed was 2 start wires (#14 or #12) and 12 to 14 #14 conductors for a remote annunciator. Generac does a lot of residential remote monitoring wirelessly these days and larger commercial sets are using the data wiring for communication.
 
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Old 08-28-13, 08:03 PM
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Similar to thermostat cable. I just had my heat pump replaced with a Carrier Infinity unit with matching thermostat. The old heat pump had a 7 or 8 wire cable. They replaced it (it had a splice it in it) with a new 4 wire cable. Two wires for 24V power and two communication wires. During setup the thermostat quired the system and in a few seconds displayed all the model and serial numbers. And it is wireless, came with a hot spot that plugged into my router so now it is live on the internet. The dealer can diagnose from his office before a truck roll.
 
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Old 08-28-13, 08:33 PM
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A little off topic, but this was mentioned before, so I thought I would show what I am dealing with in my main panel. This is a pic of the raw knockouts I have to correct. I thought I would show you guys cause you always seem to see things us rank amateurs overlook.
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Trying to anticipate the obvious questions: The six #6 wires stuffed tightly in the hole just to the left of the center KO are the heat pump and heat strip circuits. I will be removing and abandoning the heat strip circuit as they have been replaced with gas. The HVAC contractor taped them up on the other end. The bare copper between the two white cables on the right is explained in the second pic.

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CasualJoe noticed a black wire going to the neutral bus in post #4. This is how that black is connected to white, about 12 inches above the panel. I hadn't seen this before, until I removed the insulation today. The only way I can think of to correct it is to go in the attic and make a splice in a box, so it will be accessible. I will close this wall up when I am finished, so I can't put a box in there. Do you guys have any better ideas? I want to fix it right. If I uncover much more like this I am going to have trouble going to sleep in this house!

One other strange circuit: When I went throughout the house to identify all the outlets and light circuits (so I could label the panel), I discovered the dishwasher (120V) is on the kitchen stove circuit (3 wire 240V) I have no idea how they tapped into that 240V circuit, or where, but I bet it ain't pretty.
 
  #22  
Old 08-28-13, 09:29 PM
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Looks like an opportunity for a panel replacement to me.

You can make a splice in a box right where the one is now if you mount the J-box to come flush to the finished face of the wall and put a blank cover on it. Or you could mount the j-box to the back and install an access panel in the wall when you finish it. Just as ideas.

When I went throughout the house to identify all the outlets and light circuits (so I could label the panel), I discovered the dishwasher (120V) is on the kitchen stove circuit (3 wire 240V) I have no idea how they tapped into that 240V circuit, or where, but I bet it ain't pretty.
Oy! No bet.
 
  #23  
Old 08-28-13, 09:43 PM
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Replacing the whole panel has occurred to me as well. But I can't figure what the advantage would be. It is already at 200A, there are more spaces than I can use. Once I get the wires in proper strain relief/bushings I really don't know what would be wrong with it.

Thanks for suggesting the j-box in that space. I can't imagine going in the attic anytime soon, with near 100 degree days ahead for the next few weeks. It is just a utility room, nothing there but that panel, the water heater and some storage, so a cover plate on the wall would never be noticed.
 
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Old 08-28-13, 09:52 PM
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Thanks for suggesting the j-box in that space. I can't imagine going in the attic anytime soon, with near 100 degree days ahead for the next few weeks. It is just a utility room, nothing there but that panel, the water heater and some storage, so a cover plate on the wall would never be noticed.
.
 
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