I think we are saying the same thing here. Here is what I posted earlier.The bad connection resistance is all concentrated in one spot with combustibles around it (plastic plug) it does not take much resistance to melt and burn being so localized.
"When you get a loose connection it creates resistance of flow and heat will start to build up and melt things. At some point along the way they will catch fire or short out and trip the breaker."
As far as resistance a low resistance will draw more current.
10 ohm's / 1440 watts at 120 volts = 12 amps
28.8 ohm's / 500 watts at 120 volts = 4.16 amps
(120 volts / 38.8 ohm's = 3.09 amps 371.13 watts)
Any time you have heat build up you have power being used. Also if both heating points have the proper voltage going to them it would be a total load they would draw. So at the heating element you are drawing 500 watts/4.16 amps (with proper voltage) come down stream to the loose connection (10 ohm's) 1440 watts/12 amps for a combine load of 1940 watts/16.16 amps. The loose connection is still letting power through to the farthest point until it fails.
Then it comes down to what Howard said,
Or the TOTAL current exceeds the breaker capacity (heating element plus resistive fault)