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Posted by Pop on November 21, 2005, 3:50 pm
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
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
--
---
twaynesdomain.com:
Best little website in
the North Country!
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Posted by SQLit on November 21, 2005, 5:51 pm
show/hide quoted text
> 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
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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Posted by m Ransley on November 21, 2005, 6:42 pm
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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Posted by Pop on November 21, 2005, 7:56 pm
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
show/hide quoted text
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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Posted by volts500 on November 24, 2005, 12:12 pm
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.
show/hide quoted text
>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 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.
show/hide quoted text
> 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:
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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> '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