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Kevio · 03-25-2019, 08:48 AM

My wife has a mobile business out of a '76 Sovereign. Last week we were running the lights and A/C off of our Champion 4750 generator (using propane). The husband of the person running the show thought it would be a good idea to throw a blanket and boxes on top of our generator to muffle the sound.

Within an hour, the electricity to the trailer cut off. I went outside to discover the situation. The generator was still running. Luckily nothing caught fire, but it did scorch the plugs where an 30amp extension met the trailer plug. We had to finish the show without lights or A/C. I ended up replacing the plugs this past weekend. The generator is usually running at about 118v under load. Would this have changed due to the heat and caused the current to melt the plugs? I didn't think to check the voltage on the generator when I uncovered it, I was too angry.

Al and Missy · 03-25-2019, 10:03 AM

What was "scorched", the extension cord plug, the generator receptacle, or both? Were the blades of the plug discolored? What do you mean by "scorched"? Were there burn marks, of just melted plastic?

According to the manual for the generator, the 30A receptacles are protected by circuit breakers. Unless the one feeding your cable failed, it seems unlikely that the current exceeded the rating of the plug/receptacle. If the plug/receptacle has burn marks, my suspicion is the plug blades or the receptacle mating parts were corroded, resulting in higher resistance and generating excessive heat at the connection points.

The generator heat might have simply melted the plastic parts, or caused the voltage to go up or down. The voltage is the determining factor. The trailer will draw current that is dependent on the voltage supplied. If the voltage went down, the AC unit would draw more current, but again, the circuit breaker should have tripped to protect the 30A rated wiring. If the voltage went up, the current drawn by the AC would go down until some failure point was reached but it doesn't sound like that was your problem.

A common problem is voltage drop in the extension cable if the wire size is inadequate. This would cause the AC to draw more current, but again the breaker should have tripped.

The only time I have had scorched, as in burned, connectors water got into the junction between the trailer plug and the extension receptacle and shorted hot to neutral. Enough heat was generated without exceeding 30A (in that small space, a few amps of current, 200-300 watts, would have been enough) to heat up and discolor the plastic.

Al

Kevio · 03-25-2019, 10:23 AM

Thanks for the detailed response! The black wire blade is where the plugs melted. The plug at the generator was fine. It was just where the extension mated. The extension is a 30amp extension cable that is the same thickness as the trailer cable.

overlander63 · 03-25-2019, 10:28 AM

Quote:

Originally Posted by Kevio

Thanks for the detailed response! The black wire blade is where the plugs melted. The plug at the generator was fine. It was just where the extension mated. The extension is a 30amp extension cable that is the same thickness as the trailer cable.

You had a bad connection at that plug.

Kevio · 03-25-2019, 10:36 AM

But wouldn't it have been the generator that caused it? It seems coincidental that it was fine at the previous show but melted within an hour of this incident.

rmkrum · 03-25-2019, 10:51 AM

Possibly the blankets and other stuff overheated the generator and reduced the output voltage, which led to excess current. However, the damage you showed is most likely to be from an overheated, bad connection. I’d say time to replace the toasted parts and drive on. I’d also have a few rather strong words with the bozo that darn near fried your generator by covering it up. His actions could have caused a bad fire.

Also, just because a breaker is marked 30 amps does not mean it will open at exactly 30 amps. They are rated at 30, but it may take a lot more to trip it. They have manufacturing tolerances and are not that precise. The extension cord and plug overheated, yes. But didn’t draw enough current to open the breaker. That to me says the connection was marginal. Replace with a heavy duty set is your best bet. If you can get the bozo to pay for the toasted parts, that would be nicer, but highly unlikely IMHO.

Molded plugs and sockets tend to be a bit marginal at best. Your new ones, properly installed, are more likely to survive better. The fact that the generator end isn’t toasted points real strong to just the molded connectors that melted being at fault. Also says your generator is rather well built...and any third party that messes with your generator needs to be stopped. I wouldn’t put up with that at all.

Kevio · 03-25-2019, 11:04 AM

Great, thanks. That's what I was thinking but since this is all new to me, I wasn't sure. I don't think the plugs were corroded, as the extension was fairly new and the trailer plug was in good shape. I definitely had a few words with the guy but tempered myself out of consideration for my wife's business. He offered to fix it but I wasn't about to let him touch anything considering he didn't know that you shouldn't cover a generator. It could have been a lot worse. Needless to say, we aren't going back to that show.

Would something like this prevent this kind of thing in the future (excluding corroded plugs)?
https://www.amazon.com/Progressive-I.../dp/B015Y9MX38

GMFL · 03-25-2019, 11:58 AM

It was a bad connection in the cord plugs. Not the generator. Low voltage or high voltage would not be the cause. Loose connections cause arcing of the contacts which work like a welder and burn the contacts up. Covering the generator would not have caused damage to the cord. It might have caused the generator to overheat if not vented damaging the generator, but not the cable. You were pulling around 18 amps and with a loose connection it could easily burn up the plugs.

rmkrum · 03-25-2019, 12:06 PM

A Progressive industries surge protector alone will not do the job. You need a surge protector and EMS combination to monitor for low voltage or excess voltage. They are a bit more expensive than a simple surge protector alone. Highly recommended by the way. It’s a lot safer and detects midwifed connections and kills power to protect trailer and people.

Note that an EMS used with a portable generator needs a jumper plug to connect ground and neutral at the generator to make the EMS protection circuitry work properly.

Most all generators have ground and neutral (green and white wires, usually) floating, and the EMS does not like that and will not pass power on to the trailer. That’s what it’s supposed to do. The bonding plug solves that minor issue.

ROBERT CROSS · 03-25-2019, 12:16 PM

...accept the $$$ offer of the box and blanket guy🥴, buy new quality cords, plugs and never again consider such a noise abatement solution.🤔

Bob
🇺🇸

Kevio · 03-25-2019, 12:19 PM

So something like this?
https://www.amazon.com/Progressive-I...dp/B01N0W4CZ8/

Are you saying to use a jumper wire from the ground plug of the EMS to the frame or ground wire on the generator?

rmkrum · 03-25-2019, 12:54 PM

That’s the portable version of the EMS I use. Mine is hardwired in the trailer behind the power panel.

The jumper plug I’m talking about is a standard three prong household plug that fits into a standard duplex outlet.

It has a wire (14-gauge is big enough) inside it jumped from the U-ground (green screw) to the neutral (wide flat prong usually) silver screw. That ties neutral and ground together.

To use it, you merely plug it into any available standard 3-prong plug on the generator. Then neutral and ground are tied together on all the generator connections including the RV-30 socket and the EMS will work right.

If you are not certain how to build one, they can be purchased. I think Camco also sells a pre-built one.

Kevio · 03-25-2019, 01:04 PM

Ah, ok. Thanks for the additional info!

rmkrum · 03-25-2019, 01:07 PM

My pleasure.

Mollysdad · 03-25-2019, 02:38 PM

Quote:

Originally Posted by rmkrum

If you are not certain how to build one, they can be purchased. I think Camco also sells a pre-built one.

Looks bad, but is really good.
At your house, your neutral and ground are tied together in the service panel.

Portable generators use what's called a "floating ground" and the EMS sees that as an open ground, thus the need for a cheater plug.
It doesn't need to be in the circuit, any unused AC outlet on the generator works

rmkrum · 03-25-2019, 06:02 PM

Yup. Great pictures! Thanks for putting them in the knowledgebase!

ChuckFeldt · 03-26-2019, 01:23 PM

Interesting bit of cause and effect thought. I have seen this before on my camper and others. The 120v 30a RV plug and recepticals seem to do a great job to 20-22a continuous load. At some point that amperage can start to create heat. What I have seen in Florida in the summer everyone in the campground is running a/c. This is when voltage drop creeps into your reality. As voltage drop happens net amps to perform the same work increase. And more heat happens in connections and wire. Heat softens the metal in the connectors which reduces connection tension resulting in your damaged connectors. The blankets on the generator likely resulted some voltage drop. With near 40a generator capacity it likely wasn’t happy but it cruised along.

drbrick · 03-31-2019, 09:24 AM

We run our Champion 3400 dual fuel on LP in the back of our TV - we have found that the sound is greatly diminished to the point that at 25 or so feet it's hardly noticeable. Yes, we leave the rear cover open

Tony Lee · 03-31-2019, 11:33 AM

Perhaps you didn't engage the plug and socket fully, or left it lying where people trip over the cord and pull the plug and socket apart

The othe problem with the generator can be easily fixed either by getting a quieter generator or locating it elsewhere and pointing the exhaust away

J-K Georgia · 03-31-2019, 11:55 AM

Quote:

Originally Posted by Kevio

Great, thanks. That's what I was thinking but since this is all new to me, I wasn't sure. I don't think the plugs were corroded, as the extension was fairly new and the trailer plug was in good shape. I definitely had a few words with the guy but tempered myself out of consideration for my wife's business. He offered to fix it but I wasn't about to let him touch anything considering he didn't know that you shouldn't cover a generator. It could have been a lot worse. Needless to say, we aren't going back to that show.

Would something like this prevent this kind of thing in the future (excluding corroded plugs)?
https://www.amazon.com/Progressive-I.../dp/B015Y9MX38

I have had two of those surge protectors with not so good results.
First one was not sealed and filled up with water, needless to say there was sparking and arcing.
Second ones plug melted just like yours but due to sloppy campground plug.