block heater cord gets real hot

[seandrisc]

after plugging my truck in for the night the block heater cord is extremely hot to the touch any idea what would cause this?

 

[Crumm]

Short in the cord or heater. My cord is stone cold after being plugged in for days. Normally any time a electrical cord of any type gets hot it is because it is being overloaded. Is the whole cord hot or just by the plug? Check the cord, connections at both ends and heater element. I would not recommend using it until you fix it, hate to see a classic 94-97 go up in a ball of flames..

 

[BIG JOE]

Short in the cord or heater. My cord is stone cold after being plugged in for days. Normally any time a electrical cord of any type gets hot it is because it is being overloaded. Is the whole cord hot or just by the plug? Check the cord, connections at both ends and heater element. I would not recommend using it until you fix it, hate to see a classic 94-97 go up in a ball of flames..

What Crumm sez and, what Guage wire is yer extention cord ? How long is it ? The longer the cord, the more voltage drop. Should be at least 12 Guage. And on a 15 amp service, with not much else on that service when yer Block Heater is on.

The plugs on our Block heaters are known for going bad.

Like Crumm sez.... I would'nt use it, til you get it figured out.

JOE

 

[WD40]

What Crumm sez and, what Guage wire is yer extention cord ? How long is it ? The longer the cord, the more voltage drop. Should be at least 12 Guage. And on a 15 amp service, with not much else on that service when yer Block Heater is on.

The plugs on our Block heaters are known for going bad.

Like Crumm sez.... I would'nt use it, til you get it figured out.

JOE

Big Joe may be hitting the nail on the head. Don;t use one of those little inside the house power cords. Mine was on last night for 10 hours and it was stonecold this AM. Hope you can fine out what's wrong soon.

 

[95_stroker]

Theres a good chance that your heater is getting ready to crap the bed, high resistance causing the cord to get hot. You could OHM it out and see what the reading is. And yes, the shorter the extension cord the better, and 12 ga. is recommended.

 

[whatabudro]

Just a couple of things for those interested.

Voltage drop:

VD = 2xLxKxI divided by CM

L = length
K = Constant ( copper = 12.9 ohms ) (aluminum = 21.2 ohms)
I = amps
CM = circular mills
18awg = 1620
16awg = 2580
14awg = 4110
12awg = 6530
10awg = 10380


I'm going to quote DAVEBEN (for formula reasons only) and say the block heater is 1000 watts.

P=IxE E=IxR (PIE & EIR)

P= power/watts
I= amps
E= voltage

E= voltage
I= amps
R= resistance

Now if you know any two variables you can figure the third.

Using P=IxE:

1000p/ 120e = 8.3i (amps)

Now back to the voltage drop formula using a 100 foot 18 gauge copper wire cord:

VD = 2xLxKxI / CM

2x100x12.9x8.33 / 1620 = 13.27%

Now we must go back and figure out the amperage again since our voltage is now 120volts minus 13.27%

100% - 13.27% = 86.73%

120volts x .87 = 104.4volts

1000p/104.4e = 9.61i

So by using that cord you raised amp draw from 8.33 to 9.61

Here is where the problem is:

18awg cord is rated at 7 amps in most cases (voltage drop doesn't matter its too small anyway)
16awg cord is rated at 10 amps in most cases

So you would think 16 awg would be fine. I was estimating your voltage at the receptacle at 120 volts to start with. Most do not have 120 volts, some are lower than 110 volts. So if we started with actual and figured the voltage drop, then the 16 gauge cord would not be large enough.



Do you want to see a formula for why you should never use a 2 wire or 3 wire cord with the ground prong missing?

 

[powerboatr]

bryan
I have never seen these formulas explained so "down to earth"
thanks

 

[Big K]

physics for the rest of yall!

 

[powerboatr]

and one easy reason teh cord gets hot at the connection.
mine has in the past on my 7.3 the male plugg would get corroded and cause a higher resistance which creates heat.

 

[seandrisc]

my cord is a short outdoor cord and i just replaced heater element and cord last year when i had a waterpump lock up