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The RVer's Open Forum / TECHNICAL RV HELP / Air Cond. 30 Amp. Service

Bernie
User ID: 2024664 Jun 28th 12:26 PM
I have been told that I can damage the Air Cond. unit on my 83 Tioga Arrow if I hookup to less than a 30 Amp. service. Is this true?

What are the problems if I run it on 15 or 20 Amps?

Marty in TN
User ID: 9099093 Jun 28th 2:58 PM
Bernie: Anything that is electrical or in electronics is possible one way or the other, so with that said------At home,I have and do run my AC out of a 15 Amp outlet BUT, I use a heavy 10 guage extension cord, I make sure my voltage stays above 115 VAC in the motor home and try to keep all else off line other then maybe the converter. So far I've had no problems. That is not to say that a sudden drop in voltage wouldn't cause hurt big time. That's the chance you take.

Incidently, I won't do this in any campground. That, to me, is too big of a gamble.

Marty

Ernie
User ID: 1265504 Jun 29th 6:25 AM
Reference: A/C voltage
The suggestions from Marty are excellent. Here is my input I hope it helps.
When the Rv is parked at home I run power from the house through a 30 to 20 amp 3-prong adapter, using a 20 amp circuit breaker from the power distribution panel . The rating on the electrical cord must be 10 amps or greater. The circuit breaker at your distribution panel must be in good shape as to not trip the breaker. Breakers get old and "soft" and will trip or cutoff at a lower amperage. The reason for the 10 amp rating on the extension cord is because the smaller the wire gauage, say a #14, the more voltage it drops to get to your a/c. Example, #14 wire you might lose 2 volts going to your A/C, #10 wire, you might lose 0.5 volts, a difference of 1.5 volts.
Note: wire size: the larger the wire size the smaller the amperage capacity.
Keep in mind that the 30 amp rating on your A/C is maximum amps like when you first turn it on, normally it runs at about 15-20 amps.
Check you distribution box(fuse box) and see if you have a 20 amp circuit breaker, Sometimes the garage is set up for 20 amps. Note 15 amps might be ok, I run off a 20 amp circuit breaker.
You might want to invest in a A/C "plug in" voltmeter. You plug this into your Rv wall socket to see how much voltage you have at the RV. If you monitor the votmeter when you turn on your A/C you will momentarily observe how much the voltage drops at turn on and when your compressor turns on and off. The A/C voltage should read 115 volts A/C, +/- 15 percent.
Ernie

tk
User ID: 1662364 Jul 29th 11:17 AM
Hi all, just a slight modification of what Ernie said: "the larger the wire size, the smaller the amp capacity" SHOULD be modified to say, the larger the wire number (14-18 guage), the smaller the amp carrying capacity compared to the the smaller number wires (8-12 guage), which are actually LARGER wires (but with smaller numbers, go figure how that system got started!).

We run our A/C at home and at campgrounds on 20 amp circuits but with the frig on propane and no other high ampreage use. No problems yet, and we do have a plug-in voltage monitor right where we can see it that glows red if voltage gets too low.

Barthbill
User ID: 8645673 Jul 29th 6:54 PM
tk, that red glow sounds handy. At what voltage does it glow red?

tk
User ID: 1662364 Jul 30th 9:04 PM
Howdy Barthbill, I just went and looked at it. It is a REC AC Power Line Monitor bought at CW some years ago, and it has a green lite that indicates normal polarity but with other combinations of two lites to indicate reverse polarity, open neutral & open ground;
and a second row of lites to indicate voltage:
green for 110-120; yellow for 100 or 130, and it looks like red below 100 volts, though I have yet to encounter that lite being on.
While I should use this monitor at the pedestal prior to hooking up, I find it easier to just plug in prior to unhooking my TT and asking the wife how the lites look before unhooking the trailer. With nothing on except the converter, I figure I'm probably safe for a few minutes doing it this way.

jd
User ID: 3640224 Jul 31st 5:52 AM
Well, tk, it's like you to have a good solution. [Unless Barthbill does, that is, then like both of you to share it!] I'd been wondering if you needed 30A for upcoming visit or could get by with 20. I set up to add 20, but might not be too bad to pull another 30 to the driveway/guest slot.

I have an ordinary "outlet polarity tester" plugged into a 30A adapter and it lives by the driver seat. When I get out at a site (we walk it before backing in) it comes to the pedestal with me. I figure if the polarity's reversed or ground open, site isn't worth parking on...

Lately we've driven more with the genny running and I'm thinking we need to add some kind of underway voltage monitor. Just saw where PPL had one for $15 that's an analog AC plugin voltmeter. Its "green zone" runs 115-125VAC according to the picture.

What I think I want is either a meter or LED setup that doesn't run on a battery so I can leave it plugged in. For the genny, I can just run a cord to where we can see it from the cockpit.

We just had a three-day beach trip, planning two more in August. Great summer weather for that, about too hot to do much else, even think outside.

God Bless, jd

Barthbill
User ID: 8645673 Jul 31st 12:35 PM
Rather than pay $15 for an analog meter, I bought a Kill A Watt for about ten dollars more. It reads volts, amps, frequency, cumulative watt-hour usage, etc. I use in in the house, too. It is also good for calculating usage of things that run off the inverter, like whether or not my batts and solar panels will support an ice maker. Just plain nifty!

Check it out on Google and Froogle.

coop
User ID: 0701364 May 11th 11:29 PM
The roof ac draws 20 amps on startup and 14 amp on run cycle...you can run on 20 amp service with no issues as long as you don't run anything else.... running on 15 amp adapter is not only bad for your ac but also a fire hazard !!!! Their is such a misconception about the 15 amp adapters and lengths of cords an sizes....Reading some basic electricity books...
As far as being able to run your ac on 15 amp yes yes maybe able to get it to after you reset the breaker a few times... but you will !!! shorten the life of it !!!!!

Bernie User ID: 2024664	Jun 28th 12:26 PM I have been told that I can damage the Air Cond. unit on my 83 Tioga Arrow if I hookup to less than a 30 Amp. service. Is this true? What are the problems if I run it on 15 or 20 Amps?
Marty in TN User ID: 9099093	Jun 28th 2:58 PM Bernie: Anything that is electrical or in electronics is possible one way or the other, so with that said------At home,I have and do run my AC out of a 15 Amp outlet BUT, I use a heavy 10 guage extension cord, I make sure my voltage stays above 115 VAC in the motor home and try to keep all else off line other then maybe the converter. So far I've had no problems. That is not to say that a sudden drop in voltage wouldn't cause hurt big time. That's the chance you take. Incidently, I won't do this in any campground. That, to me, is too big of a gamble. Marty
Ernie User ID: 1265504	Jun 29th 6:25 AM Reference: A/C voltage The suggestions from Marty are excellent. Here is my input I hope it helps. When the Rv is parked at home I run power from the house through a 30 to 20 amp 3-prong adapter, using a 20 amp circuit breaker from the power distribution panel . The rating on the electrical cord must be 10 amps or greater. The circuit breaker at your distribution panel must be in good shape as to not trip the breaker. Breakers get old and "soft" and will trip or cutoff at a lower amperage. The reason for the 10 amp rating on the extension cord is because the smaller the wire gauage, say a #14, the more voltage it drops to get to your a/c. Example, #14 wire you might lose 2 volts going to your A/C, #10 wire, you might lose 0.5 volts, a difference of 1.5 volts. Note: wire size: the larger the wire size the smaller the amperage capacity. Keep in mind that the 30 amp rating on your A/C is maximum amps like when you first turn it on, normally it runs at about 15-20 amps. Check you distribution box(fuse box) and see if you have a 20 amp circuit breaker, Sometimes the garage is set up for 20 amps. Note 15 amps might be ok, I run off a 20 amp circuit breaker. You might want to invest in a A/C "plug in" voltmeter. You plug this into your Rv wall socket to see how much voltage you have at the RV. If you monitor the votmeter when you turn on your A/C you will momentarily observe how much the voltage drops at turn on and when your compressor turns on and off. The A/C voltage should read 115 volts A/C, +/- 15 percent. Ernie
tk User ID: 1662364	Jul 29th 11:17 AM Hi all, just a slight modification of what Ernie said: "the larger the wire size, the smaller the amp capacity" SHOULD be modified to say, the larger the wire number (14-18 guage), the smaller the amp carrying capacity compared to the the smaller number wires (8-12 guage), which are actually LARGER wires (but with smaller numbers, go figure how that system got started!). We run our A/C at home and at campgrounds on 20 amp circuits but with the frig on propane and no other high ampreage use. No problems yet, and we do have a plug-in voltage monitor right where we can see it that glows red if voltage gets too low.
Barthbill User ID: 8645673	Jul 29th 6:54 PM tk, that red glow sounds handy. At what voltage does it glow red?
tk User ID: 1662364	Jul 30th 9:04 PM Howdy Barthbill, I just went and looked at it. It is a REC AC Power Line Monitor bought at CW some years ago, and it has a green lite that indicates normal polarity but with other combinations of two lites to indicate reverse polarity, open neutral & open ground; and a second row of lites to indicate voltage: green for 110-120; yellow for 100 or 130, and it looks like red below 100 volts, though I have yet to encounter that lite being on. While I should use this monitor at the pedestal prior to hooking up, I find it easier to just plug in prior to unhooking my TT and asking the wife how the lites look before unhooking the trailer. With nothing on except the converter, I figure I'm probably safe for a few minutes doing it this way.
jd User ID: 3640224	Jul 31st 5:52 AM Well, tk, it's like you to have a good solution. [Unless Barthbill does, that is, then like both of you to share it!] I'd been wondering if you needed 30A for upcoming visit or could get by with 20. I set up to add 20, but might not be too bad to pull another 30 to the driveway/guest slot. I have an ordinary "outlet polarity tester" plugged into a 30A adapter and it lives by the driver seat. When I get out at a site (we walk it before backing in) it comes to the pedestal with me. I figure if the polarity's reversed or ground open, site isn't worth parking on... Lately we've driven more with the genny running and I'm thinking we need to add some kind of underway voltage monitor. Just saw where PPL had one for $15 that's an analog AC plugin voltmeter. Its "green zone" runs 115-125VAC according to the picture. What I think I want is either a meter or LED setup that doesn't run on a battery so I can leave it plugged in. For the genny, I can just run a cord to where we can see it from the cockpit. We just had a three-day beach trip, planning two more in August. Great summer weather for that, about too hot to do much else, even think outside. God Bless, jd
Barthbill User ID: 8645673	Jul 31st 12:35 PM Rather than pay $15 for an analog meter, I bought a Kill A Watt for about ten dollars more. It reads volts, amps, frequency, cumulative watt-hour usage, etc. I use in in the house, too. It is also good for calculating usage of things that run off the inverter, like whether or not my batts and solar panels will support an ice maker. Just plain nifty! Check it out on Google and Froogle.
coop User ID: 0701364	May 11th 11:29 PM The roof ac draws 20 amps on startup and 14 amp on run cycle...you can run on 20 amp service with no issues as long as you don't run anything else.... running on 15 amp adapter is not only bad for your ac but also a fire hazard !!!! Their is such a misconception about the 15 amp adapters and lengths of cords an sizes....Reading some basic electricity books... As far as being able to run your ac on 15 amp yes yes maybe able to get it to after you reset the breaker a few times... but you will !!! shorten the life of it !!!!!