Problems Using 120V - 30 Amp Power?

[Swingshiftworker]

I just took my AT Horizon trailer out for a test run and the camp ground I went to provides power via a 120V-30Amp outlet -- 2 prongs in a v configuration w/a grounding prong below. So, I bought a 120V-30Amp adapter at an RV shop so that I could use a normal grounded 120V extension cord with it. The vendor "warned" me that I should watch out because I could "burn out" anything that I run with it.

My laptop and iPod charger seemed to work fine off of this connector, but the 10amp Guest Charge Pro Battery Charger feeding the AGM 31 battery in the trailer seemed to heat up too much and was acting "strangely" (alternating red/green lights). So, heeding the vendor's warning, I disconnected it. Tried the 120V 400watt inverter in my FJ Cruiser (which I believe only puts out about 3 amps) and the battery charger seemed to work fine. Also worked fine after I hooked it back up to regular AC power in my garage.

So, the question is: Will using the 120V-30amp power at a campground with a regular 120V adapter damage the battery charger (or anything else) and, if so, what do I need to do (or buy) in order to step down the power so that that doesn't happen?

[njtaco]

So, the question is: Will using the 120V-30amp power at a campground with a regular 120V adapter damage the battery charger (or anything else) and, if so, what do I need to do (or buy) in order to step down the power so that that doesn't happen?

No problem using a 30-15A adapter at all. HOWEVER you need to make sure the campground is wired correctly. Use a GFCI tester with lights to be sure of polarity, and a volt/ohm meter to be sure of voltage. It is common for campgrounds to have power issues.

Note: the GFCI tester is not used to check GFCI in this case, just polarity. Pushing the "button" should have no effect.

[Swingshiftworker]

No problem using a 30-15A adapter at all. HOWEVER you need to make sure the campground is wired correctly. Use a GFCI tester with lights to be sure of polarity, and a volt/ohm meter to be sure of voltage. It is common for campgrounds to have power issues.

Thanks!

I've got one of both of those and will throw them in the trailer to check when I hookup at that (or another) campground again.

[Martyn]

Sounds like a polarity wiring issue. Some devices like your iPod charger don't care if the polarity is standard or reversed but the solid state circuit of the battery charger may not like it at all.

From what I've read most of the RV crowd carry 110 volt polarity testers and test the campground electrics before plugging in. Mis-wired campsites are very common evidently. You should be able to pick up a tester at your local hardware store.

[Swingshiftworker]

Sounds like a polarity wiring issue. . . . Mis-wired campsites are very common evidently. You should be able to pick up a tester at your local hardware store.

Thanks for the additional tip. I think my circuit tester checks for polarity. If not, I'll just buy a separate polarity tester too.

[chrismc]

I think the vendor's "burn out" warning was due to the higher amperage breaker on the 30A circuit. Since most 120V devices are designed for 15A and 20A circuit protection, you can easily overload components in your electrical system before the 30A breaker will trip. An example would be if you were running a couple space heaters and a microwave on the same extension cord. Normally, that configuration would cause the breaker to trip since you'd be pulling more amperage than the circuit could safely deliver. With the breaker upped to 30A, you could easily set your extension cord on fire with the added current draw before the breaker would step in. In short, be sure to carefully monitor your current draw. Add up everything that you have plugged in, and make sure you are not exceeding the weakest link in your system. If you are using a 14GA extension cord, do not exceed 15A total draw (1800 watt total). A 12GA extension cord will get you up to 20A (2400 watt total). If you have long extension cords, then the amount of power you can safely draw will drop. It doesn't sound like you're using any high-draw appliances, or are anywhere near capacity, but please be careful.

The issue with the charger could be bad polarity, as others have mentioned. It could also be low voltage on the line. As other also mentioned, campgrounds have notoriously bad power. Oftentimes, they don't use appropriate wiring, or over-allocate electric circuits. This can lead to circuits that are under-voltage. You can test the circuit with an AC voltage tester, or multimeter. A nicer option is to buy a Kill-A-Watt ($20) electric meter. This will give you all kinds of nice info about the power you're drawing, including voltage, actual live amperage draw, frequency, etc.. It can also track total watt usage, which would be super-useful to help with sizing a battery/inverter electric system to play off-the-grid.

[Swingshiftworker]

I think the vendor's "burn out" warning was due to the higher amperage breaker on the 30A circuit. Since most 120V devices are designed for 15A and 20A circuit protection, you can easily overload components in your electrical system before the 30A breaker will trip. An example would be if you were running a couple space heaters and a microwave on the same extension cord. Normally, that configuration would cause the breaker to trip since you'd be pulling more amperage than the circuit could safely deliver. With the breaker upped to 30A, you could easily set your extension cord on fire with the added current draw before the breaker would step in. In short, be sure to carefully monitor your current draw. Add up everything that you have plugged in, and make sure you are not exceeding the weakest link in your system. If you are using a 14GA extension cord, do not exceed 15A total draw (1800 watt total). A 12GA extension cord will get you up to 20A (2400 watt total). If you have long extension cords, then the amount of power you can safely draw will drop. It doesn't sound like you're using any high-draw appliances, or are anywhere near capacity, but please be careful.

The issue with the charger could be bad polarity, as others have mentioned. It could also be low voltage on the line. As other also mentioned, campgrounds have notoriously bad power. Oftentimes, they don't use appropriate wiring, or over-allocate electric circuits. This can lead to circuits that are under-voltage. You can test the circuit with an AC voltage tester, or multimeter. A nicer option is to buy a Kill-A-Watt ($20) electric meter. This will give you all kinds of nice info about the power you're drawing, including voltage, actual live amperage draw, frequency, etc.. It can also track total watt usage, which would be super-useful to help with sizing a battery/inverter electric system to play off-the-grid.

More good info, thanks!

FYI, I'm just using a standard 14ga 100 ft extension cord to provide power for my laptop (and other electric gizmos) and for my trailer's battery charger -- no appliances or power tools -- so power use and risk is minimal, but I'll keep all of this info in mind.