A little help for my son's generator

[jsb5717]

Just checking the electrical expertise here.

My son has a 30 amp TT. He has a generator that should be adequate but it keeps popping the breaker when the AC is turned on. There are 2 settings for the 30 amp plug...either 120v or 240v. He's using the 120v but it won't work.

This is his generator. Any thoughts?

http://www.ngcindustries.com/11-8120.html

Thanks for the help

[Customer1]

Which breaker? On the generator or in the RV? What size is the breaker?

Definitely plug into 120.

[wiredgeorge]

Is the 30A 120V outlet on the generator the same as the plug on your son's RV cord? The 3500w (running) should be OK to run an RV a/c unit otherwise so we are likely missing something. And as already asked; pops the main in the trailer or the breaker on the generator?

[jsb5717]

It pops the generator breaker. The breaker doesn't indicate what amps it's protecting so it must be a general breaker for any over-draw.

The plug is a 4 pin twist but he bought the adapter for the RV plug from an RV dealer

I appreciate the help. I'm no expert in electrical so not sure what's going on. Seems like it should work.

[flygrimm]

jsb5717

Your first step is to hook up the generator to the trailer and run some other AC items like the microwave or just plug in something to one of the regular AC outlets. If all is well there then the air conditioner compressor might be drawing too many amps during startup (known as locked rotor amps). Also make sure nothing else is drawing power from the generator except the trailer's converter.

What is the rating of the air conditioner? 13,500 btu, 15,000 btu or something else. Does the air work when hooked up to shore power?

Your generator has a continuous rating of 3500 Watts and a surge rating of 4000 so it should handle the air conditioner, but not much else. I have the champion 3400 Watt inverter generator with a continuous rating of 3100 Watts and it runs our 13,500 btu air no problem, just don't ask it to run the microwave at the same time ;).

If the air is in good working order, it might just have a high startup amperage. You can try installing a hard start capacitor (the least expensive option) or try the Easy Start from Micro Air (a bit expensive).


Hard start capacitor: example only, your air conditioner might require a different model
https://smile.amazon.com/Supco-SPP6-Hard-Start-Kit/dp/B00DZUAPQG/ref=sr_1_2?crid=1UAL5K23SUKUM&keywords=rv+hard+start+capacitor&qid=1565799433&s=gateway&sprefix=rv+hard%2Caps%2C127&sr=8-2l.


Easy Start:
https://www.microair.net/products/easystart-364-3-ton-single-phase-soft-starter-for-air-conditioners?variant=30176048267

[JRTJH]

The generator appears to be a "off brand knock-off" obtained from a mail order business. I'm not suggesting that the generator is not worth the price paid, rather that many "low cost, off brand" generators are either "rebranded rejects" or "remanufactured and rebranded, low cost sales items"....

You didn't indicate that there's any problem when the trailer is connected to shore power, so if it's working on shore power, then the 30 amp RV main breaker is carrying the correct load and the A/C is working. That means the trailer is probably working normally (or the 30 amp trailer breaker would open with the A/C load). Assuming that it works on shore power, I'd suspect it's a generator issue.

Before spending a lot of time on trying to troubleshoot the trailer for possible problems, it looks like this is your son's generator and the problems are with the generator, when connected to his trailer....

Why not connect his generator to YOUR trailer, see if you can replicate an approximate "amp draw" by turning on ONE of your air conditioners. If the breaker on the generator does the same with YOUR trailer, I'd suspect the generator first and not the trailer. If, however, the generator performs well in powering YOUR trailer, then I'd suspect that your son may have an issue with his air conditioner and/or his trailer....

I'd suggest you verify that it's the generator or his trailer by connecting to YOUR trailer to see if the generator is performing to specifications. That way, you'll know where to focus your efforts rather than "blaming both and trying to find out which one".....

[jsb5717]

flygrimm and JRTJH,

Thanks, guys, good suggestions. I did suggest that he try running other stuff from the generator as a test. His trailer works fine on 30A or 50A (with plug adapter) shore power and runs the AC as it should.

Also, his AC is 13,500 BTU

I am also suspecting the generator itself.

[jsb5717]

Just confirmed with my son that the generator powers the coach and runs everything, including the microwave, except the AC. With everything else off, the AC alone pops the breaker.

[flygrimm]

Seems to me that the generator cannot handle the startup amperage for the air conditioner. Could be the breaker on the generator is faulty, the stated startup watts (4000) for the generator are overstated or there is a fault with the generator.

Try the generator on another trailer if possible and see if it starts that air conditioner.

Try another generator if you can get access to one.

I might try a hard start kit on your son's trailer. It's only about $20 and can be installed DIY in less than an hour. Lots if video's on YouTube.

Stuart

[jsb5717]

Thanks, it does feel like the generator is weaker than stated. We are hooking it up to my trailer this Saturday to test that theory.

Thanks for the help

[flygrimm]

How did your test with the generators go?

Stuart

[jsb5717]

Thanks for checking. The jury is still out. He can plug into the std household 120 outlet (20a) and run the coach just fine. However, in the 4 prong 240/120 outlet with an RV adapter plug the breaker pops. Still not sure why...

[flygrimm]

If it's the breaker on the generator that keeps popping, I would think that there is something wrong with the generator. Bad breaker, bad wiring, maybe the adapter is faulty. Just some ideas. Were you ever able to hook up the suspect generator to something else or try a different generator on your son's rig?

Stuart

[duh1]

I have a 2910bh Keystone pssport and tried 3 generators till i found the champion 3500 weight 90 lbs would run out trailer ac and frig not sure if i turn on all the lights but it does what is needed (home depot about 950 bucks) they have larger more potent ones but i wanted to be able to lift it myself and are much cheaper. good luck

[jsb5717]

Thanks, I suspect something wrong with the gen. The same breaker operates both outlets. There is a selector switch to determine which outlet you're using. The breaker does't pop on the 20amp side, but does on the 30amp side.

We've also used 2 different adapter plugs with the same result.

[Roscommon48]

you got the answer, the generator can't deal with the A/C.

The new 2200 Honda generator is operate a 13.5btu a/c

[jsb5717]

The confusing part is that it runs the AC just fine on the 20a side, but not on the 30a side.

[xrated]

The confusing part is that it runs the AC just fine on the 20a side, but not on the 30a side.

I may be wrong with this answer, but it seems feasible to me. The 30A twist lock type receptacle is able to provide 30A total at 120V...which equals 3600 Watts. But each leg of the 120 is only going to be able to provide 15A each...for a total of 30A. Since the A/C unit is 120V and is only being supplied from one of the hot legs, using the 30A twist lock recept is actually only providing 15A from that one leg. Basically, the other 120V leg is not being used. So 30A total....15A on each leg. Most likely there is nothing wrong with the generator, and the breaker is doing exactly what it should be doing, opening up or tripping because of the current being higher than 15A at start up.

[Wxman]

Using the correct adapter? Xrated may be on to something in a sense. Since the generator is voltage selectable it should be able to put out the max watts at the 30 amp receptacle in the 120V only mode, correct? Somehow the switch parallels the load after the circuit breakers to give the max watts. But I believe it would still take both legs (hots) to get the max watts but they can be combined when in the 120V only mode. However, if the adapter is incorrect it may only be connecting one leg (hot) to the RV end of the adapter, which as would seem to limit to 15amps.
I am not a pro, but I think it would be interesting to know if both 'hots' of the adapter have continuity to the 'hot' of the RV side of the adapter.

[bobbecky]

Using the correct adapter? Xrated may be on to something in a sense. Since the generator is voltage selectable it should be able to put out the max watts at the 30 amp receptacle in the 120V only mode, correct? Somehow the switch parallels the load after the circuit breakers to give the max watts. But I believe it would still take both legs (hots) to get the max watts but they can be combined when in the 120V only mode. However, if the adapter is incorrect it may only be connecting one leg (hot) to the RV end of the adapter, which as would seem to limit to 15amps.
I am not a pro, but I think it would be interesting to know if both 'hots' of the adapter have continuity to the 'hot' of the RV side of the adapter.

If the 30 amp outlet is set up to provide only 120/240 volts from the four leg outlet, there may not be a switch to actually select one voltage or the other, and if that is the case, the two hotlegs will be out of phase and are not able to be paralleled, so the 15 amps per hotleg is probably the what is wrong and why the A/C will not work. The dogbone adapter is only using one of the hotlegs to feed the 30 amp shore cable, just like if you were connected to a 50 amp pedestal, you are only using one of the 50 amp hotlegs, but that works in that situation. Another sad thing is, this generator has a 7 HP engine and doesn't really put out that much more power than our two little 2,000 watt Honda's paralleled, 2.8 HP each.

[jsb5717]

We tried 2 different plugs...one from an RV dealer and one from Amazon. Both are supposed to be specifically for this application. My guess is you guys are right, that dropping a leg cuts the amps. How would you wire a plug to keep 30a on 120v?

[xrated]

We tried 2 different plugs...one from an RV dealer and one from Amazon. Both are supposed to be specifically for this application. My guess is you guys are right, that dropping a leg cuts the amps. How would you wire a plug to keep 30a on 120v?

I don't think you can.....the two 120V legs are 180 degrees out of phase with each other....and makes the output 240V instead of 120V

[xrated]

Using the correct adapter? Xrated may be on to something in a sense. Since the generator is voltage selectable it should be able to put out the max watts at the 30 amp receptacle in the 120V only mode, correct? Somehow the switch parallels the load after the circuit breakers to give the max watts. But I believe it would still take both legs (hots) to get the max watts but they can be combined when in the 120V only mode. However, if the adapter is incorrect it may only be connecting one leg (hot) to the RV end of the adapter, which as would seem to limit to 15amps.
I am not a pro, but I think it would be interesting to know if both 'hots' of the adapter have continuity to the 'hot' of the RV side of the adapter.

I'm not sure that you are understanding what I'm trying to say. When the switch is set to 240V, the max current available is 15 amps....which equals 3600 Watts. When the switch is set to 120V, the total is 30 amps, but that is 15 amps for one hot leg and 15 amps for the other hot leg, for a total of 30. But you are only using one hot leg at a time on the generator out put. It's basically the same thing as the power coming into your house....two hot legs (180 degrees out of phase with each other) and a neutral. If you only have one of the phases and a neutral, you are only getting half of the available power.

[Wxman]

OK. His generator has a 120V only switch. The switch should parallel the output and make the full wattage available for 120V. It appears in this case JMAC did not include a 120V 30A receptacle to get all that power out in 120V. It probably does parallel the load at the 120V receptacle and gives the full 20A (2400W)(limited by circuit breaker) instead of only the 1750W (half of genny output) of a single leg. His switch does not convert the 240 outlet to 120 and no adapter is going to do that. The switchable genny I was somewhat familiar with and an additional 120V 30A outlet. Running in 120V only mode paralleled the output and made the entire 30A available at that outlet while making the 240 outlet unusable. The OP's genny doesn't appear to have that option. Looks like limited to 2400W at the 120V receptacle by circuit breaker in 120V mode instead of 1750W (half of genny output), in 120/240 mode, but no way to get full 30A because doesn't have the additional receptacle.
Yes, I see no way to get 30A at 120V from his 4 prong 240V receptacle.
Has certainly exhausted my understanding. I'm out.

[jsb5717]

I assumed (dangerous, I know) that there was a universality to generators that had this kind of plug since there are adapter plugs made for them that are supposed to work with RV's. I don't know how to test the plug for amperage on each leg but it appears that your assumptions are correct since the gen fails to power the AC on the 30a 4 prong side but does so on the 20a side.

If that's true then the stated specs for the gen are deceptive. It states 30a AC 120/240v. It should say 15a/30a AC 120/240v.

[xrated]

OK. His generator has a 120V only switch. The switch should parallel the output and make the full wattage available for 120V. It appears in this case JMAC did not include a 120V 30A receptacle to get all that power out in 120V. It probably does parallel the load at the 120V receptacle and gives the full 20A (2400W)(limited by circuit breaker) instead of only the 1750W (half of genny output) of a single leg. His switch does not convert the 240 outlet to 120 and no adapter is going to do that. The switchable genny I was somewhat familiar with and an additional 120V 30A outlet. Running in 120V only mode paralleled the output and made the entire 30A available at that outlet while making the 240 outlet unusable. The OP's genny doesn't appear to have that option. Looks like limited to 2400W at the 120V receptacle by circuit breaker in 120V mode instead of 1750W (half of genny output), in 120/240 mode, but no way to get full 30A because doesn't have the additional receptacle.
Yes, I see no way to get 30A at 120V from his 4 prong 240V receptacle.
Has certainly exhausted my understanding. I'm out.

I did do some reading on small generator outputs and how the are built. I think YOU may be spot on with your last post. I've never really dealt with small generators and I've learned a bit myself....both from you and from a bit of reading

Here's the page I was reading.....

https://www.generatorjoe.net/html/generatorops.html

[flygrimm]

I believe you are correct. There is no way to connect both hot legs together to get the full amperage/wattage as they are out of phase with one another. Looks like this gen is not really what it's advertised to be.

If your son just wants a gen for the trailer I would probably try to sell this gen to a contractor or someone who needs that type of gen and use the proceeds to get an RV specific gen. I have the Champion 100263 3400 Watt dual fuel inverter generator and am happy with it. I think you would be happy with any of the brands in this range.

[jsb5717]

That may be the solution...we've talked about that.

I did just get off the phone with the manufacturer who seems to think that we should be able to use the gen as we intended and finds it odd that we can't. One of their techs said he would do some research and get back to me...we'll see. If they do I'll report what they say.