power cord plug melting

Yup the difference between 100 amps @ 120 VAC for 50 amp service to 30 amps for 30 amp service.

I have found that when using 30 amp service and actually pulling 28-30 amps for a few hours on the cord, the cord will scorch and slightly melt. If the cord is having to hold only about 20-25 amps, it does ok, but long term at 28-30 amps, it will melt the cord eventually. So if you are a 50 amp coach, using the dogbone to use 30 amp service, you are likely using close to the maximum on that 30 amp cord, and unless you're careful it will scorch the cord and possibly melt it. It is a great example of the difference in 50 amp campers verses 30 amp. 2 legs of 50amp verses 1 leg of 30amp. big difference.

The molded ends of a typical 30 amp cord have crimp wire connections that are weak at best.
New replacement ends with screw terminals should help.

www.progressiveindustries.net/rv-adapters

Consider a surge protector to monitor power in addition to protecting the RV. For best results limit power to 24 amps.
(see link)

Most 30 amp park plugs are old, worn and dirty. They wear and become loose allowing a poor connection with you plug. This causes heat and can melt the plug. Look at a new plug and see how shiny it is, then compare it to your plug. Yours is dull and may have black areas that have been hot. This causes a poor connection and also heat. Since park owners aren't going to change their receptacles unless it fails completely, it falls on us to change our 30 amp plugs.

DrewE wrote:

fla-gypsy wrote:

Canadian Rainbirds wrote:

Lynnmor wrote:
It sounds like he is plugging in to a 30A outlet. The 30A breaker (if there is one) would trip if he is drawing more power than his equipment is rated for. The real problem is likely high resistance at the plug due to either a burned plug or receptacle.

My thought too. (It's happened to me!)

Low voltage can result in burnt plugs also

Not directly. Low voltage causes some things (most notably the air conditioner) to use more current, which causes more power dissipation in a poor connection, which causes more heating. But that's the result of increased current flow, not of the voltage of the source. Many loads consume less current at lower voltages; heating elements and light bulbs are in this category.

Melting and burning are caused by localized heat, which is caused by localized power consumption. Electrical power consumption, in watts, is voltage (across whatever is consuming the power) multiplied by applied current. A poor connection, whatever its cause, has a higher resistance than it should, leading to a larger voltage drop, and so more power consumed at that point. If you have a 2V drop at 20A, say, it matters not whether the supply is 120V (and the load proper sees 118V while the bad connection sees 2V) or 12V (and the load sees 10V while the bad connection sees 2V). The bad connection has to somehow sink 40W of heat in either case.

While your technical explanation is correct and the time spent explaining it enlightening, I surmised the OP who claims to know little about electrical didn't need a detailed explanation and a burnt plug is still toast regardless of the role the voltage drop played it its demise directly or indirectly. A serious voltage drop can result in the OP's problem, the end result being the same.

> have to find another end to replace it

Amazon is your friend.

But very important, stop trying to slurp 50 amps through a 30 amp straw. You'll wake up sometime wondering what that bright orange flickering light outside is.

cor4743 wrote:
Agreed that poor connection causes arcing and generates heat. That is the case right now. Due to melting, the plug is fitting very loosely, and I have to find another end to replace it. I am currently on a three week trip in Washington nd Oregon, so unable to get at my 50 amp cord, which is at home.

The other thing is that both ends of the cord did fit snugly when new, and I am on my second plug, so now need a third til I get home.

Get a 50 amp cord, and camp at RV parks where there are 50 amp outlets. You need 50 amps, per 120V leg, and a 50 amp plug has two 50 amp legs, where as a 30 amp plug has only one 30 amp leg. A 50 amp plug provides 3.3X the amount of amperage at 120V, or 100 Amps, as a 30 amp 120V plug providing only 30 amps at 120V.

100/30 = 3.3X

You keep repeating the same mistake, over and over, and expect a different result, what does Einstein call that? Get a 50 amp cord and go camp where there's a 50 amp outlet, before you burn something down.

Agreed that poor connection causes arcing and generates heat. That is the case right now. Due to melting, the plug is fitting very loosely, and I have to find another end to replace it. I am currently on a three week trip in Washington nd Oregon, so unable to get at my 50 amp cord, which is at home.

The other thing is that both ends of the cord did fit snugly when new, and I am on my second plug, so now need a third til I get home.

fla-gypsy wrote:

Canadian Rainbirds wrote:

Lynnmor wrote:
It sounds like he is plugging in to a 30A outlet. The 30A breaker (if there is one) would trip if he is drawing more power than his equipment is rated for. The real problem is likely high resistance at the plug due to either a burned plug or receptacle.

My thought too. (It's happened to me!)

Low voltage can result in burnt plugs also

Not directly. Low voltage causes some things (most notably the air conditioner) to use more current, which causes more power dissipation in a poor connection, which causes more heating. But that's the result of increased current flow, not of the voltage of the source. Many loads consume less current at lower voltages; heating elements and light bulbs are in this category.

Melting and burning are caused by localized heat, which is caused by localized power consumption. Electrical power consumption, in watts, is voltage (across whatever is consuming the power) multiplied by applied current. A poor connection, whatever its cause, has a higher resistance than it should, leading to a larger voltage drop, and so more power consumed at that point. If you have a 2V drop at 20A, say, it matters not whether the supply is 120V (and the load proper sees 118V while the bad connection sees 2V) or 12V (and the load sees 10V while the bad connection sees 2V). The bad connection has to somehow sink 40W of heat in either case.

If you should dissect some of those cords and see the shoddy workmanship and materials it would have you spinning Tibetan Prayer Wheels. The problem is how they connect the copper wire to brass terminals.