AC on 20a service?

bshpilot wrote:

NinerBikes wrote:
Being in AZ, 115f and the possible head temps at the compressor at start up, using a 20 amp jack is feasible, but every time that AC starts up, it's a potential problem, as the compressor probably has a locked rotor amperage draw of 60+ amps.

Possible, yes. Good for MIL's electrical or you electrical, no, not at all. Keep an eye on the connector and cord temperatures, go out and check them at A?C compressor start up, before you burn something down. Huge current surge at start up, every single time.

I monitor my consumption very closely - and my plugs have never shown any sign of warmth.
Even in houston weather (w/ a clamp-meter) I've never seen the start up consumption anywhere close to the 50a or 60a you speak of

if i was connected to a marginal outlet (below 115v & incapable of 20a) i wouldnt be concerned - but like i said I've monitor & tested my consumption very close & never seen the peaks you claim.

Read my statement again... but a little more carefully this time...

"Dammit how many times is it going to take to impress the fact that an AC restating on high head can draw FIFTY AMPERES? Yes it is for a short time. Just long enough for a loose or corroded contact in the plug or receptacle to glow red hot."

The paragraph contains information. What information in that paragraph may differ from how your AC operates on your plug? The words CAN. LOOSE. CORRODED are three clues.

An inductive load is reactive. If the voltage drops at a connection that is taxed NEAR TO it's capacity, amperage is going to rise dramatically. Ever see what happens in a REACTIVE situation where a slightly bad connection goes from warm to flames in 5 seconds?

It takes a very good connection meaning in very good condition to withstand a high head restart. You are fortunate enough to have been connected with a very good connection.

And yes I have seen several high head restarts that consumed 50+ amperes. My usual response:

Shut it down! There is a bad connection somewhere.

You have to deal with reality on this not pick and choose specifications and data. I know of few RV'ers who shut off all the lights and other 12 volt loads to pamper the AC. It all adds up.

Add the minor loads to a high head re-start and the recommendation for a 20-amp connection should read: The receptacle and plug MUST be in perfect condition...

The recommendation should not read "Oh yeah, it's OK. plugger in and go for it."

Unless of course a person does not care about receptacle and plug fires, losing power in the middle of the night and all the other benefits that come with being reasonably careful.

I recommend research. Research the subject of actual data of what happens to current demands when voltage drops. You need either a recording peak ammeter, or an analog quality ammeter and shunt to respond fast enough to see the current surge. I was not exaggerating when I claimed the reactive V sag and I surge can flame an outlet contact in seconds. It's scary.

And to the OP: YES YES YES! Please get a hard start kit installed IMHO.

NinerBikes wrote:
Being in AZ, 115f and the possible head temps at the compressor at start up, using a 20 amp jack is feasible, but every time that AC starts up, it's a potential problem, as the compressor probably has a locked rotor amperage draw of 60+ amps.

Possible, yes. Good for MIL's electrical or you electrical, no, not at all. Keep an eye on the connector and cord temperatures, go out and check them at A?C compressor start up, before you burn something down. Huge current surge at start up, every single time.

I monitor my consumption very closely - and my plugs have never shown any sign of warmth.
Even in houston weather (w/ a clamp-meter) I've never seen the start up consumption anywhere close to the 50a or 60a you speak of.

if i was connected to a marginal outlet (below 115v & incapable of 20a) i wouldnt be concerned - but like i said I've monitor & tested my consumption very close & never seen the peaks you claim.

Thanks for the input.

I can't check the breaker right now but will before we try to run the AC. Where we will be is in the higher desert of NM, south of Albuquerque (at least I think it's high desert}. It's cooler there than here but still summer.

So, would a hard start capacitor help lessen the load at start up? Would it possibly reduce the load on the 20a service?

If at all possible use your 30 amp shore cord with a dogbone or a very hefty and short extension cord. Check temp of cord at all connection points after 30 minutes or so of use, and keep and eye on input voltage as anything under 108Vac will put extra duress on your compressor causing it to fail prematurely. May not fail immediately but will shorten it's overall lifespan if operated under less than ideal conditions for prolonged periods. Hope your MIL has a short and successful recovery.

Keith Haw wrote:
Hello

Just have a question about running a 13.5k AC on a standard 20a/110v power cord.
The DW's mom has to go in for a major operation and we will be taking the TT, mostly because of the pets. Her mom has a setup for the trailer as they used to do a lot of camping in past years. However, we're probably going to be there a couple weeks and they only have a standard 20a/110v service setup. I'm fairly sure we are going to need the AC while we're there. I was wondering if I can run the AC on this or do I need to hookup the genny.

Thanks
Keith

I know you stated that it was a 20a "service" setup, but did you check to see if it actually had a 20a breaker in the main panel and if the outlet was a 20a outlet per the attached pic?

20a outlet configuration

Dave H M wrote:
heck yeah, I do it all the time. My RV cord does reach the plug in without an extension. Been going onto 14 years in the current location.

Plug her in.

One day, you just might be paying that high deductible on your insurance. Just because you've been doing it, doesn't make it to code, or right, or safe. Ask any licensed electrical contractor, not the helper, the one that knows how to do load calculations on circuits.

Keith Haw wrote:
Thanks for all the replies

I'm glad to know it should be ok. I've never tried to run the AC on anything less than 30a. either genny or plugin, so wasn't sure.

Thanks again.
Keith

Being in AZ, 115f and the possible head temps at the compressor at start up, using a 20 amp jack is feasible, but every time that AC starts up, it's a potential problem, as the compressor probably has a locked rotor amperage draw of 60+ amps.

Possible, yes. Good for MIL's electrical or you electrical, no, not at all. Keep an eye on the connector and cord temperatures, go out and check them at A?C compressor start up, before you burn something down. Huge current surge at start up, every single time.

Thanks for all the replies

I'm glad to know it should be ok. I've never tried to run the AC on anything less than 30a. either genny or plugin, so wasn't sure.

Thanks again.
Keith

i do it all the time on my MIL's curb...i run my 50a cord to the house w/ the necessary adapters & have no problem running one of our ac units. As others have said - i keep the fridge and water heater on gas.

i installed some panel meters to keep tabs on the voltage & current input and consumption....20 bucks for 2 digital panel meters (30a coaches would only need one meter).