Portable Generator Wiring to Transfer Switch

Cross-posted; f'ups to a.h.r. So if you read it once, you read 'em all.
I'm (finally) getting around to installing a transfer switch for my portable generator. The purpose of my post here is to check for any NEC violations, or safety issues, whatever. I've had the switch over two years so I think it's time I installed it. I'll pass my final decisions past my local code enforcement officer so it'll all be done to code, and will be inspected. From my initial contact, he wants to see a schematic representation of the installation in a line drawing. No problem there.
Country: US. Very rural area, lose power often.
I have a 5,000W generator with an L5-30 120/30A receptacle and an L14-20 120/240V 20A receptacle. I plan to use the 120/240 so I can run the well pump, 1 HP, 240V submersible, so I need the split phase output. There are no other 240V appliances other than the dryer, which I'm not worried about running. It'll be about the only thing can run when it's needed, but that's OK; one or two lights after the pump gets started and I should be fine current-wise. I'm not worried about managing capacity. The generator DOES have breakers, and it's an industrial grade generator for what it's worth. The Transfer Switch, a 7,500 watt device, has a 125/250V 30A plug on it to connect to it. I'm not planning to use an outdoor Power Inlet Box, simply because 1. There is a disconnect at the generator itself, and the generator will be located right beside the power meter when it's used, under an overhang, but completely outdoors and highly visible. 2. It costs money and only about 7-8 ft of cord are required anyway.
Here are my questions: -- Can I avoid use of the outdoor Power Input box and still satisfy the requirement for a manual disconnect? As I said, the cord is simply plugged and unplugged from the generator itself. Inside of course, the cord can be pulled from the transfer switch also. The transfer switch is mounted right next to the mains breaker box. Reading the requirements it's confusing; they say a manual disconnect is necessary, and the box is an option item, but ... why? I could see if it were direct-wired to the generator, but it's not. I can't find an allowance for the generator manual disconnect, in other words.
-- I'll have to use a 20A 4-wire cord with the L14-20 plug on one end for the generator, and a 125/25-V 30A receptacle on the other end to connect to the transfer switch. Any problems with using 20A wiring on a 30A receptacle? Can't see why there would be.
-- I'm also planning to run the cord into the house through a piece of steel conduit to manage passing thru the wall. Inside, the cord will just run up the wall to the transfer switch and plug in there. The transfer switch is right next to the breaker box. Outside the wall it'll connect to the generator and i'll build a small box to house the cord neatly and out of sight when it's not in use. Might be a good idea to padlock it away from kids etc., hadn't thought of that, but that's why I'm posting my quest, to pick up details like that, too.
All the diagrams I see indicate an outdoor power inlet box outside and a junction box inside. The run for the cord is so short I'm trying to bypass using either of those.
-- And, one last question: If I read things right, I do NOT use the ground strap on the generator to attach to the house ground, right? It's right there and would be easy to use a clamp-on, but from what I read it's not required and in some ways not desirable. It derives its earth from the breaker box in this case, and not the ground rod. Right?
Thanks for any comments or thoughts you may have; I appreciate your taking time to consider my post. I've tried to keep it simple.
Regards,
Pop
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I can not see the installation and that in itself makes any recommendations "blurry" at best.
The manual disconnect that I believe your talking about is the disconnect from the utility. This disconnect is usually mechanically inter-locked so that only the utility or gen feed can be on. a double throw 3 pole switch will work for this depending on the installation. SQD has a breaker made for some of their panels that is all ready set up for this.
The ground is a problem. I can not see your set so, basics are. Ground the genset with a ground conductor to the service. 4 wires needed to the service. Grounding to the service makes sure that the gen and utility and the neutrals are all the same potential. Neutral is the grounded conductor. Some folks will use a double throw double pole switch making the neutral solid. I do not like this cause if there is a fault or imbalance on the neutral the energy could go to the gen set, if connected. http://www.emergencyswitch.com /
http://www.mayberrys.com/honda/generator/html/transfer.htm
Both these sites have some diagrams to help out.
You still need to have protection for the generator, the plug idea you mentioned should work cause the outlet should be protected by a breaker on the genset.
Grounding is really important. The electricity needs a path back to the generator through a conductor to trip the breaker.
Clear????? as mud??????
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I question your generator frame gound, my Generac goes right to the dirt from its frame lug nut to a wire attached to a rod thrown down, its a ground for my unit. Your idea of building a box for the gen plug should be ok. Running a gen 7 ft from the house for me is to close, ive had measurable co inside from 10 ft, they consume alot of gas. If your transfer panel has no watt meters get them, and a permanently mounted voltmeter for each leg.
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Thanks, that all sounds like good advice.
: I question your generator frame gound, my Generac goes right to the : dirt from its frame lug nut to a wire attached to a rod thrown down, its : a ground for my unit.
Yeah, I'm questioning it too. I've always read/understood though, that you don't gang up on earth grounds. So, since the L14 P/R/C has two 120V pins, one Neutral and one Earth( genset frame when it's plugged in), I -think- it's all earthed correctly when you plug the generator in. I'm not sure what, if anything, grounding the genset frame would do - it would make it a 2-earthed system, though, which as I understand it, is a no-no. No? <g>.
: Your idea of building a box for the gen plug should be ok. Running a : gen 7 ft from the house for me is to close, ive had measurable co inside : from 10 ft, they consume alot of gas.
Gaswise, the gen throttles down when there is no load, so that helps gas consumption a little.
True. I think I'm OK but we'll see if any CO alarms go off. I know my car will set them off quickly but never had the generator bother. We've used it with a mess and tangle of extension cords and jumpers (for the well pump & furnace) a few times without noticing any problems. It's always been winter when we need it so doors & windows are closed. Only time I ever noticed it was once I left the garage door open 'cause I had a gas can sitting there; that was the ice storm of '98 - long time with no power! Ran out of gas, had to use my car's fuel pump to get gas out of it - THAT was scary! Lucked out though; didn't blow anything up. Someday I'll figure out how to siphon gas from my cars! Ain't like it used to be!
: If your transfer panel has no watt meters get them, and a permanently : mounted voltmeter for each leg.
It does; one wattmeter for each leg. Not very large, but they'll give an idea of the load on each side. No voltmeter though; that does sound like a good idea. Good catch.
Thanks,
Pop :
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POP wrote:
: I question your generator frame gound, my Generac goes right to the : dirt from its frame lug nut to a wire attached to a rod thrown down, its : a ground for my unit.

Almost correct. If you're using a transfer switch that doesn't switch the neutral and a 4-wire cable that plugs into the generator, the generator neutral (white wire) and the generator equipment ground (green wire) must _not_ be bonded together at the generator. Some small generators have a "bond link" just for that purpose. Check for continuity between the generator neutral and the equipment ground at one of the receptacles. If you have continuity, then they are bonded and you'll have to change it so that they aren't.
> I'm not sure what, if anything, grounding the genset frame

The system that you are installing is NON-Separately Derived. The requirements for a non-separately derived system (in your case) are:
1...Use a 4-wire cable, two hots, a neutral, and an equipment ground. 2...DO NOT bond the neutral and the equipment ground _at_ the generator. (most small generators are bonded at the factory) 3...The neutral is solidly connected to the normal power neutral in the transfer switch (The neutral is NOT switched).
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Aha! I think you've hit the clarification I needed but wasn't asking correctly! Inline, please:
:: I question your generator frame gound, my Generac goes right to : the :: dirt from its frame lug nut to a wire attached to a rod thrown : down, its :: a ground for my unit. : : >Yeah, I'm questioning it too. I've always read/understood : >though, that you don't gang up on earth grounds. So, since the : >L14 P/R/C has two 120V pins, one Neutral and one Earth( genset : >frame when it's plugged in), I -think- it's all earthed correctly : >when you plug the generator in. : : Almost correct. If you're using a transfer switch that doesn't switch : the neutral ===> Exactly; it does not switch the neutral.
and a 4-wire cable that plugs into the generator, ---> That's the plan
: ... the : generator neutral (white wire) and the generator equipment ground : (green wire) must _not_ be bonded together at the generator. ===> THAT has been the missing component for me! Neutral and Earth are not connected in the generator; I checked with an ohmmeter. THAT makes the 4-wire cable make sense now! The neutral of the gen connects to the neutral of the breaker box and the frame of the gen connects to the earth of the breaker box; thus, all are bonded at and only at the breaker box tie points. For a moment, that left me wondering then, why there would be a large ground lug on the generator. But that now makes sense, too: IFF I were to use the L5-14 3-wire receptacle on the generator for, say, a worksite instead of emergency house power, THEN I would need the earth lug on the gen for an earth ground! Or even, I suppose, if there were a power panel with no earth ground yet, then I'd use the genset earth. In this case it would have nothing to do with the power company but would be a safety issue. Right?
I'm hoping you agree, because now it finally all makes sense to me. Or that at least I'm not too far out into left field yet.
: ... Some : small generators have a "bond link" just for that purpose. ===> Not that I can see externally at least. Maybe under a cover someplace but ... nothing visible, nothing in the manual.
Check for : continuity between the generator neutral and the equipment ground at : one of the receptacles. If you have continuity, then they are bonded : and you'll have to change it so that they aren't. ===> Done. Not connected. : : > I'm not sure what, if anything, grounding the genset frame : >would do - it would make it a 2-earthed system, though, which as : >I understand it, is a no-no. No? <g>. : : The system that you are installing is NON-Separately Derived. The : requirements for a non-separately derived system (in your case) are: ===> Ha! "separately derived": intellectually I know what that means, but w/r to the industry, I'm not so sure. Something to Google on since it's not real clear to me. : : 1...Use a 4-wire cable, two hots, a neutral, and an equipment ground. ===> That's the plan : 2...DO NOT bond the neutral and the equipment ground _at_ the : generator. (most small generators are bonded at the f ===> Yup. Dunno what it's supposed to mean, but this is an "Industrial" generator. The control panel has a duplex 120, an L5-14 30A and 3-wire and an L14 4-wire 20A receptacles. Plus the idle with no-load switch, ignition switch and choke lever. The manual talks about both job-site and emergency house powering but doesn't go into the earthing situation at all other than to say be sure to meet all codes. : 3...The neutral is solidly connected to the normal power neutral in the : transfer switch (The neutral is NOT switched). : Thanks; I suppose I sound like the smart-ass student that keeps asking silly sidelight questions but I only feel comfortable about things when I have a full understanding of what I have and what I'm causing to happen. Real or not, it's a comfort level for me.
Regards,
Tom
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POP wrote:

Exactly! You got it POP.

Well........not really. If the generator gets used as a jobsite generator, you want to make sure that the neutral and equipment ground are bonded together, of course. It's not required to connect a small generator to an earth ground for jobsite use where tools and such are plugged into the generator. However, for added safety, to keep the generator at ground potential, there is certainly nothing wrong with driving a ground and connecting it to the ground lug on the generator with a #4 bare wire.

Since all electric services have to be grounded, that would be a hypothetical yes. Again, in that case make sure that the neutral and equipment ground on the generator are bonded together.

The bond link is usually in a connection box or behind a cover. It's just a bar with two holes in it that is bolted-in across the neutral and the equipment ground, on larger generators anyway. You may not have one on that small generator. There has to be a way to bond the generator neutral to the generator equipment ground though. You may be able to come off of the ground lug on the frame to an exposed neutral connection point in a connection box. The owners manual should cover that.

That makes two of us :-)
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Hi,
I imght sound like it, but I'm NOT being snide here. Either you or I probably have a syntax "problem" which causes me to not quite get what you're trying to say. I suspect you may be trying to walk me thru some stuff, but first I actually need answers to the specific questions I asked. So, as you read the inline responses, don't get miffed at me: I speak in short sentences as a rule and it makes me sound terse, I know. It's a result of a concussion I suffered some years ago.
: > Cross-posted; f'ups to a.h.r. So if you read it once, you read : > 'em all. ... : : I can not see the installation and that in itself makes any recommendations : "blurry" at best. Obviously. That's why I tried to post the questions clearly and definitively. : : The manual disconnect that I believe your talking about is the disconnect : from the utility.
No, I'm specifically talking about a mechanical disconnect for the generator. Almost every image shows an outdoor power inlet box, a cable from the generator to that, while the other side of the power inlet box goes inside to a junction box, and then a cable goes from that junction box to the transfer switch. Honestly, it looks more like money-making than the real requirements.
: ... This disconnect is usually mechanically inter-locked so : that only the utility or gen feed can be on.
That's the purpose of a transfer switch. They're DPTT switches; util, nothing, or gen. BBM due to the middle position.
: a double throw 3 pole switch will work for this depending on the : installation. SQD has a breaker made for some of their panels that is all : ready set up for this.
Like I said, I have the transfer switch. : : The ground is a problem. I can not see your set so, basics are. Ground the : genset with a ground conductor to the service. 4 wires needed to the : service. There are 4 wires: That's what an L14-20 is. L14-20 et al are NEMA grades.
: ... Grounding to the service makes sure that the gen and utility and : the neutrals are all the same potential.
That's the reason for the 4-conductor L14-20 NEMA, is it not? I know that's 4-wires, one earthed, and my interpretation was that was all that was needed for earthing. The earth lugs on the gen aren't required with an L14-20 set. I've only seen the generator ground required when it's used say as power for a bldg site. But, omission isn't the way to read codes <g>, so figured I should find out. Seems you agree with me.
Neutral is the grounded : conductor. Dunno what you mean.
: Some folks will use a double throw double pole switch making the neutral : solid. I do not like this cause if there is a fault or imbalance on the : neutral the energy could go to the gen set, if connected.
?? again. When you're not useing a portable gen set, it's disconnected. Maybe you're talking about imbalance being placed on the generator istelf? Agreed, sort of, depending on the load. Actually, it appears I'll have a fairly balanced loading; it just worked out that way. Makes me wonder if the breaker box wasn't set up that way on purpose, actually.
: http://www.emergencyswitch.com / : : http://www.mayberrys.com/honda/generator/html/transfer.htm : : Both these sites have some diagrams to help out. Yup, you're right. But I already knew that stuff. That and more's included with the transfer switch I got a few years back and am now finally getting around to installing. : : You still need to have protection for the generator, the plug idea you : mentioned should work cause the outlet should be protected by a breaker on : the genset. Yup, generator has its own breakers. The transfer switch also has smaller breakers. I think it's 6 @ 15A, two @ 20A and a pair of ganged 20A. Any two of the others can be ganged too with a bar provided, but I won't need to use it. : : Grounding is really important. The electricity needs a path back to the : generator through a conductor to trip the breaker.
Again, I believe that's one of the L14 wires? : : What about the 20A at one end of the cable and a 30A on the other for gen to switch? : :
Thanks,
Pop
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Im sure a frame ground strap or like my wing nut goes right to dirt, at least for my Generac its that way. Try alt.energy.homepower alot of gen heads there. A V meter is good because 120v is 60 hz, and many motors need 60hz. Other than that I think you are safe, a digital read out co meter will let you know of any issues before they are problems.
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A generator frame ground is a saftey issue , incase your generator goes bad so you dont get killed turning it off or just touching it.
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That's a good point!
:A generator frame ground is a saftey issue , incase your generator goes : bad so you dont get killed turning it off or just touching it. :
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