30 amp power cord overheating

Dielectric grease is an insulator, but in the process of plugging in the connection it gets wiped out of the way of the actual contact points (assuming it is being applied and used properly).

Conductive materials or greases with suspended metal ("conductive grease") have their own problems, not the least of which is the possibility of creating a current leak or even short circuit.

This page has more information than you probably ever wanted to know, and passes my sniff test.

I thought silicone dielectric grease was not a good conductor?

Any, meaning the tiniest hint of overheating at the plug or socket pins, the socket or plug must be discarded and replaced with a new plug or socket. These connections rely utterly on spring tension to make a secure electrical connection.

When they overheat then cool the spring tension disappears and limp noodle syndrome sets in. This is caused by ANNEALING which can happen to copper and brass.

When you strip the insulation of the black, white & green pigtails, the wire can be scraped to bright copper if black or violet color. But you cannot use stripped pigtails of the wire is green or dull red. Red means red, not aged copper. When in doubt bend the strands, if they bend like cooked spaghetti then you have to re-cut the cable further back and try there.

Overheated plugs and sockets CAN NOT BE SALVAGED. Replace them as a mating pair.

Assemble using silicone dielectric grease. De-Oxit D100 does not last as long as Silicone grease, even the hideously expensive L-De-Oxit does not protect as well or last as long as a glop of silicone grease. I own all this stuff and have learned about them via The School Of Hard Knocks.

If you try and cheat on doing the cable repair correctly, you are going to pay a truly unpleasant penalty later on. Also from the school of hard knocks.

Another vote for it being the connectors, and not the wire gauge (which would heat the entire cable).
I really like the Progressive Industries TT30R and TT30P connectors, much better quality than any others I have seen. Remember on the molded plugs the terminal is just press fit on the end of the wire, and if you overheat those once, they continue to deteriorate.

The male and female plugs are either oxidized or not making a firm connection. Replace both with good quality plugs and that problem should go away.

Get some deoxit. Tread the plugs. If they are bad--then replace--and treat with deoxit.

I've had issues running extension cords for our old 30 amp MH, with plugs overheating even when connected to 30 amps at a campground or at home. I wonder if its caused when the plugs are on wet grass or out in the rain? May need to take steps to keep them dry. Just my thoughts.

wire gauge is NOT your problem if the prongs or connector are showing heat fatigue. It's likely either a worn out or poorly designed socket and/or plug.

The easiest cure is to cut off the offending ends that are showing heat fatique and replace them with high quality plugs and sockets. Marinco is one such brand but there are others as well.

Oops, should have included that bit. The outlet I'm plugging into is a 30 amp RV box I installed myself, and I did use 8 ga wire for the run from breaker box. It has been used for a year or so, and has been rock solid and passes the SurgeArrest tests.

Yard camping usually implies your hooked into 15 amp house connection - if so that is likely at max capacity running just the AC and might not even be able to do that depending on type/length of extension cord. When I do that I usually switch the fridge and hot water heater to propane and use a kill-a-watt to monitor the voltage in the rig to make sure it doesn't drop too low and damage the air conditioner. If your batteries are low the converter can also be a major electric draw.