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Small Cabin Forum / Off-Grid Living / Portable Generator and a/c help
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jrbarnard
Member
# Posted: 27 Jun 2012 06:30am
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Maybe you guys can help me...

It will be a few more months before we get electricity hooked up and the heat in Texas is unreal atm. So, I have 2 generators at my cabin. Normally, I hook one up and place it outside the cabin, plugging it into a receptacle that powers the "circuit" inside the cabin...nothing fancy, just a few lights etc, not even a breaker box since the generator has it's own.

The generators are all Troy-Bilt Model 030429 5500 watt generators from HD.

I bought a 23,500 BTU A/C for the new cabin and wanted to hook it up at the current one since the heat dissipation in the current one is non-existent...i.e. there is no radiant barrier, no metal roof, no shade.. it catches all the heat all day long.. heh

It is 12x24 with a loft... so this unit SHOULD be able to cool it....at least enough to be bearable.

Here is the issue: The A/C is a model LW2410HR LG window unit. It has a 20amp/230volt plug, the one that has an off-set 3-wire tab.

Now, if I unplug everything from the cabin circuit and install a plug for that.. the generator SHOULD be able to power it, right?

The only other option is to make a 4-wire extension/conversion cord to plug the a/c directly into the generator, which I do not mind.. but I am not sure what to do about a 4-wire to a 3-wire conversion.

I mean, do I get a 3-wire cable and just hook up 3 of the wires to the 4-wire plug that goes into the generator, or do I get a 4-wire cable and hook up 2 of the wires to the 3-wire plug that the a/c plugs into?

HD or Lowes have the parts.. but they say it cannot be done and I am like.. hey.. it can be done, you just do not know how. They answer, with something about how they might make a conversion kit at the mfg...but the mfg person that answers the calls just places me on hold then hangs up because I stumped them.

So.. I am sure there is a brilliant person here that has had this issue :p

Russ

Force_Multiplier
Member
# Posted: 27 Jun 2012 06:51am
Reply 


so the A/C has a plug like a welder or a 220v dryer.... I'd start w/ the local welding supply people hook welders to generators all the time...

as for will the generator run the a/c... probably... barely... to know for sure you find the starting amps... then multiply amps x volts (220) for watts... so if your unit runs at 10A... 10x220=2200 watts running, but it'll spike when the compressor first kicks on....

I read once that a window A/C takes, on average, 4800 watts at start up... but the best way to find out is to use a Kill-a-watt meter on your's and see...

jrbarnard
Member
# Posted: 27 Jun 2012 07:08am
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the generator is a 5500 watt generator with 8200 watts startup...so it should run well. The only problem I have is getting said electricity TO the thing.. heh. I'll call around and see if any welding places know.. thanks ;l)

Russ

VTweekender
Member
# Posted: 27 Jun 2012 07:51am - Edited by: VTweekender
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When converting the 3 prong plug on the AC to 4 prong plug you would simply not use the neutral on the plug, there are 2 hots of 120 each and a ground coming from the AC, the 4 plug has 2 hots , ground, and neutral, just hook the 2 hots and ground....

See this explaination http://www.askmehelpdesk.com/appliances/converting-3-prong-4-prong-plug-297490.html

jrbarnard
Member
# Posted: 27 Jun 2012 08:35am
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Thank you very much for the help. Here are the two types of plugs. I am betting it should be fairly easy to figure out, just hope I get the wires connected to the right ones.. heh

Wish me luck! ;)

I am pretty handy with stuff like this, I just like to research and figure it out as much as possible BEFORE I try to do it :p

Russ
3-prong plug to A/C
3-prong plug to A/C
4-prong plug into generator
4-prong plug into generator


jrbarnard
Member
# Posted: 27 Jun 2012 09:19am
Reply 


BTW: Thanks for all the help. This makes me feel a lot better about what I am trying to do.

I think the 5500 watt generator should be able to run the A/C plus at least 1 low wattage light, maybe 2, that use like 9 watts.

This only needs to last about 4 months and we should have the electrical poles.

We also can run a 2nd generator with an electrical cord in a window to power the lights if need be.

Russ

cman47c
Member
# Posted: 27 Jun 2012 09:54am
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The 3 prong plug to A/C is dedicated to 230 VAC. The 4 prong plug is 120/230 VAC. If you look close at the 4-prong plug, the prongs are marked X, Y, W, G. The X is one leg of 230V, the Y is the other leg of 230 V and G is ground. Polarity will not matter. Those are the 2 wires you need plus the ground. The W is for the 120V, i.e. either X or Y and W will be 120 VAC. The ground prong is the one with the little jog on it.

jrbarnard
Member
# Posted: 27 Jun 2012 10:14am
Reply 


Ok, so assuming I only need a 3-wire strand to make the cable with.. I would leave off the "W" on the 4-wire plug?

I would connect the X and the Y and the G.. and leave off the W.. then on the 230VAC, I would connect the same 3?

Hope I got that right ;)

Russ

cman47c
Member
# Posted: 27 Jun 2012 10:46am - Edited by: cman47c
Reply 


Yep, I do it all the time. As long as your plugged into the generator 120/230V twistlock. I run my 230V hot water heater and water pump this way. As a side note, if you have a voltmeter, I usually check my wiring and make sure I have 230V at the new plug end.

jrbarnard
Member
# Posted: 27 Jun 2012 11:08am
Reply 


Excellent.. tyvm.

Russ

MSS
# Posted: 25 Dec 2012 09:30pm
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Need to convert a 4 wire 30amp generator cord coming from my generator transfer outside outlet box to a 3 wire 20amp so I can plug it into my generator. What wire do I leave out when I go from 4 - 3?
I will not be drawing more than 20amps at one time. back up generator only for fridge, lights and turning on gas furnace.

larry
Member
# Posted: 25 Dec 2012 10:14pm
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review the previous posts in this thread it is all been answered

toyota_mdt_tech
Member
# Posted: 26 Dec 2012 12:31am - Edited by: toyota_mdt_tech
Reply 


Quoting: VTweekender
When converting the 3 prong plug on the AC to 4 prong plug you would simply not use the neutral on the plug, there are 2 hots of 120 each and a ground coming from the AC, the 4 plug has 2 hots , ground, and neutral, just hook the 2 hots and ground....



That would be perfect, except on a generator, you may not actually have a ground unless you pound in a ground rod and hook up a ground, but then its a floating ground. Generators if you use a circuit tester test shows "open ground"

If the circuit uses only line and line (220V) and not 2 110V circuits, ie 110V from one leg runs compressor, other leg runs fan and control panel, then it would work.

I think in his case, he would use "line, line and neutral" for his AC to work. Red and black, go to the gold screws on the plug, white or neutral to the silver screw, ignore the green wire (if you buy 4 wire cord) otherwise, use back and white to gold screws, green to silver screw. I'd buy the 4 wire cord, just ignore the green wire.

toyota_mdt_tech
Member
# Posted: 26 Dec 2012 12:38am - Edited by: toyota_mdt_tech
Reply 


Quoting: jrbarnard
Thank you very much for the help. Here are the two types of plugs. I am betting it should be fairly easy to figure out, just hope I get the wires connected to the right ones.. heh

Wish me luck! ;)

I am pretty handy with stuff like this, I just like to research and figure it out as much as possible BEFORE I try to do it :p

Russ



Russ, use the 4 prong twistlock. The 3 prong I see looks like just a 20 amps 110V plug.

If you use 3 wire conductor, just hook your wires to X, Y and W. (black and white to X and Y, and ground wire (be neutral now) to W

MSS
# Posted: 26 Dec 2012 08:43pm
Reply 


Generator transfer switch issue??? Generator has 3 wire locking plug, 1 phase output, transfer switch has 2 phase 4 wire locking plug. I was told by the generator manufacturer that I will only be able to power one phase of the transfer switch with this generator.( 3 of the 6 circuits) They recommended I purchase an upgraded generator with a 4 prong 2 phase output.. (Current is 3500 peak watts.) The transfer switch company said new generator not necessary. I can convert the 1 phase 3 wire to a 2 phase 4 wire. My question is how do I wire this conversion?? I purchased an L5-30P Turnlok Plug which has the three terminals

toyota_mdt_tech
Member
# Posted: 27 Dec 2012 09:07am
Reply 


Quoting: MSS
Generator transfer switch issue??? Generator has 3 wire locking plug, 1 phase output, transfer switch has 2 phase 4 wire locking plug. I was told by the generator manufacturer that I will only be able to power one phase of the transfer switch with this generator.( 3 of the 6 circuits) They recommended I purchase an upgraded generator with a 4 prong 2 phase output.. (Current is 3500 peak watts.) The transfer switch company said new generator not necessary. I can convert the 1 phase 3 wire to a 2 phase 4 wire. My question is how do I wire this conversion?? I purchased an L5-30P Turnlok Plug which has the three terminals



MSS, is your 3 prong twist lock a 220V outlet or a 110V outlet? And what amperage is it rated for?

Do you have a picture of the twist lock plug or specs sheet on your gennie?

You do not have 2 phases, you have single phase to your home, you have a line 1 and a line 2, neutral and a ground.

Are you hooking this up to a cabin that isnt hooked to the grid? There is a workaround either way.

MSS
# Posted: 27 Dec 2012 11:57am
Reply 


The twist lock is a 125v, 2 pole, 3 wire, rated for 30amps.
I am hooking this up as a back-up generator to a house on the grid. I was told to tie the 2 hot wires from the 4 prong twist lock plug coming from the transfer switch to the only hot lead on the 3 wire twist lock plug, than neutral and ground coming from the generator. This should power both sides (line 1 & 2) of the transfer switch each having 3 circuits.

toyota_mdt_tech
Member
# Posted: 27 Dec 2012 03:58pm
Reply 


MSS, yes, that wil work.

MSS
# Posted: 28 Dec 2012 10:37am
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Thanks for your input

toyota_mdt_tech
Member
# Posted: 28 Dec 2012 10:52am
Reply 


I did basically the same deal, except mine is off grid, I used a "jumper" to tie both legs together inside my interior fuse panel. Same principle. Works great. Being as you are on grid, that wouldnt be best for you. Doing it right inside the adapter cord is perfect. Just use heavy enough wire, ie 10AWG and bigger (smaller number) if its a long cord.

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