30 amp power cord overheating

[deepdoc1]

I've searched around and can't find the info I'm looking for. I have a 30' 30-amp shore power cord hard-wired to a built-in Surge Arrest, and I frequently use a 30' 30-amp extension cord for yard camping. I've noticed the prongs starting to show signs of overheating where the shore cord and the extension are connected together.

I occasionally run the AC, and may sometimes forget to switch the water heater to propane while running AC, so that may be the culprit. I am thinking I need to replace the cords, but I had an idea I need to check out with the wizards here.

My thought is to make my own upgraded cords using two 30' lengths of 8/3 or even 6/3 (or 6/3 - 8/1 if I can't find 3 conductor) SOOW from HD or Lowes. My thought is that the OTC 30-amp cords are at their limit with 10 ga, so going fatter may reduce heating issues.

Most other best practices are being followed (for the most part) such as making sure the power is off at the post before connecting or disconnecting the cords, etc. Thoughts? Tips?

Thanks!

[Sam_Spade]

deepdoc1 wrote:
or put nothing inside, just button it up and go? Thanks!

This. At least until you have used it long enough to know that the problem is solved.


And if the connection is via screw terminals, it is good to give them a little extra torque every few weeks for the first couple of months.

When you are sure that everything is good, then you can pot them if you really want to. Probably not necessary if it will be generally waterproof without it.

[deepdoc1]

Ok, I have the replacement cord ends, and I need some clarification of some of the above suggestions. When I have the wires attached to the new plugs, before I button up the plug should I fill the inside of the plug shell with dielectric grease, or neutral-cure silicone caulk (safe for electrical stuff), or put nothing inside, just button it up and go? Thanks!

[myredracer]

Great idea. Think I will make one up.

We were at one CG a couple of years ago that only had 30 amp pedestals and were all really, really old - so bad I had to use a stick to keep the 30 amp plug from falling out. No tester needed there... That's when I decided to buy a 30 to 30 amp pigtail adapter for the next time it happens.

MEXICOWANDERER wrote:
I've seen strands of copper annealed "pink (red) until they felt like strands of a paint-brush under pressure of a finger. These problems usually occur at the wire-to-terminal socket of plug and socket and not between the actual plug and socket themselves. My made-up plug on Quicksilver is soldered to the wire. I have a made-it-myself steel and plastic plug insert to check socket prong tightness one at a time. I cannot tell you how many single slots I found loose as a goose. Yet if a regular plug is inserted, it feels "tight enough"

Simply remove one tang from a plug. Get a block of wood then roughly gouge out a fox hole just big enough to hide the base of the pin. Use JB Weld to epoxy the base of the pin to the wood. I used a large knob to grip with.

Checking socket tang tightness is a heck of a lot easier than replacing a plug.

Insert plug into socket to be checked. It should fit tight. Then try and twist the tool. It should not twist -at all-

[DFord]

myredracer, that's the way my cord would look after a weekend during cool weather. Since I started squeezing a little dielectric grease into the sockets before plugging in, I no longer have that problem.

I little corrosion causes a higher resistance. Heat is the product of that resistance. As it heats up, oxidation accelerates causing even more resistance and heat. Eventually the heat builds up enough to turn the copper prong on the plug black and take the temper out of the socket. The hard rubber plug holding the male prongs melts and deforms. All that's left is a mess.

[MEXICOWANDERER]

I've seen strands of copper annealed "pink (red) until they felt like strands of a paint-brush under pressure of a finger. These problems usually occur at the wire-to-terminal socket of plug and socket and not between the actual plug and socket themselves. My made-up plug on Quicksilver is soldered to the wire. I have a made-it-myself steel and plastic plug insert to check socket prong tightness one at a time. I cannot tell you how many single slots I found loose as a goose. Yet if a regular plug is inserted, it feels "tight enough"

Simply remove one tang from a plug. Get a block of wood then roughly gouge out a fox hole just big enough to hide the base of the pin. Use JB Weld to epoxy the base of the pin to the wood. I used a large knob to grip with.

Checking socket tang tightness is a heck of a lot easier than replacing a plug.

Insert plug into socket to be checked. It should fit tight. Then try and twist the tool. It should not twist -at all-

[myredracer]

If you are doing it, stop plugging in while the power is on. Turn a breaker either off inside house or inside your RV. If you plug in live, there is a brief inrush caused by the converter - can hear a zap and in the dark can see a flash. Causes pitting of the plug blades and contacts inside a recept. Attracts dirt leading to poor contact, overheating and eventually a meltdown.

Pedestals often have 30 amp recepts. in bad shape but you can't see inside them. They get a lot of abuse. If a one looks tired, crispy and/or has low retention force, use a 50 amp recept. (if available) with adapter pigtail or if no alternative, use a 30 to 30 amp pigtail adapter so if there is overheating and damage, you shore power cord will be okay. If a pedestal recept. seems loose, don't use it.

Always make sure your plug blades are clean.

Don't let your shore power cord plug get like this:

[NinerBikes]

MEXICOWANDERER wrote:



This is where I must strongly disagree. If the contacts are discolored, they are annealed. You can shine them until they are like mirrors, but without a tight fit, armageddon is inevitable. Especially if operated near max capacity. You cannot buff resilience back into a spring. Contacts have "wipers" whose actions vanish forever if overheated. Too many times I have seen campers spend hours disassembling and shining contacts only to see disaster arrive a few weeks more. You might get away with shining up a plug if it isn't burned too bad, but not a socket. Once overheated it has had the course.

NOTICE THE WORD "DISCOLORED" It has significant meaning here

Discolored in brass or copper product means annealed or softened, and in a female socket that indeed does mean that it's lost proper gripping tension on the blade, which enhances conductivity. Time for a new socket.

[wa8yxm]

This is very common on 30 amp cords. CLEAN the prongs (Wire brush "Tip" in a Dremel works well) and clean the outlet (Emery board cut to the same size as the prong a few times in and out) Treat with De-Ox-It Gold.. Repeat as needed.

[Sam_Spade]

MEXICOWANDERER wrote:
Smearing Silicone Grease on the contacts will not hinder conductivity....period.

Not right. Period.

IF there is some degradation in the contacts to begin with....like reduced contact pressure or pre-existing corrosion, smearing insulating grease on them often just MAKES MATTERS WORSE.

Dielectric grease was really intended to be packed around contact points and into the shell of connectors. It also functions pretty good for contact devices that depend on a cutting or scraping action.
It is NOT good for applying to flat surface conductors before they are put together. AFTER they are plugged together is quite another matter.

[azrving]

Good link Drew.
Who ever goes around telling people to not use silicone grease, please stop. 🙂 I keep running into fellow rvers who think that putting anything on a wire is bad.

I have used sdg forever and even received service bulletins from companies like Cat and Hyster recommending its use. The oxidation and corrosion of unprotected metals increase the resistance. I always tell people to take 2 pieces of metal and smear any grease all over one and put nothing on the other and throw them out in your backyard for a few months then go see which one is in better shape.

Before we had weather pack flat four trailer harnesses it was a constant battle with corroded blue butt connectors. Back then even if you filled the connector with regular old bearing grease it would last far longer than no grease. Putting heat shrink over them helped even more.

No, I'm not recommending regular grease but it proves the theory of not having the components begin to corrode and cause resistance which causes heat and more corrosion and resistance. Wet greasy connections are good. Placing a glob of regular grease on places where ground cables are bolted to the frame will stay corrosion free for a long time. When you need to remove it they come apart easily. I smear regular grease on all my battery posts and lugs. When it's time to remove them just wipe it off and everything is in good shape. Who cares what it looks likes and why fight with corroded hardware.

[MEXICOWANDERER]

Sam Spade wrote:

pianotuna wrote:
I thought silicone dielectric grease was not a good conductor?

It is NOT.

Of course it isn't.


And the paint on your car wont do much to help if you get into an accident. Micro critiquing a subject into individual components then focusing on that component rather than the entire subject is fraught with peril. one of confusion.

"How's the weather today?"

"There is a substantial pressure gradient developing 1,200 miles to the west which will.. therefore despite the warm sunshine and calm air..."

I prefer to deal with what is important - reducing development of corrosion which damaged a connection through heat. Smearing Silicone Grease on the contacts will not hinder conductivity....period.

I purchase ARCTIC SILVER heat sink compound. It contains greater than 50% Silver by weight. Whew what a conductor silver is. The resistance of Arctic Silver is in the Megohm range. I plan to adhere a Shottky 500-ampere rectifier base directly to a large heatink. The copper base of the rectifier twin is the cathode. The heat sink will be dead as a centerline skunk. 🙂

[Ed_Gee]

ktmrfs wrote:
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.

What KTMRFS said above is most likely your problem and how you should deal with it. I'll strongly second his suggestion for you.

[DFord]

The male plugs have a lot of metal compared to the tabs that rub on them inside the female socket. The breaker may be rated for 30 amps but you'll never get a full 30 amps through it and even if the breaker didn't trip, you'll never get a full 30 amps across the plug/sockets labelled 30 amps. There's just not enough surface area to carry that kind of load. The dielectric grease helps to prevent oxidation which is a killer to a good connection. When using wire nuts, I'll put a little in them, especially if it's in a damp location. I keep a tube in my toolbag so it's handy.

Dielectric grease has really helped my situation. I avoid using the furnace because I can get by with two 1500 watt heaters on their low (800 watt) settings and still use another high draw appliance like the water heater OR the microwave.

[Sam_Spade]

pianotuna wrote:
I thought silicone dielectric grease was not a good conductor?

It is NOT.