Heating block overheating

[FireChick]

A friend of mine's father has a ram diesel had his truck plugged in the other night. He came out in the morning to find the electrical cord and the heater block cord fused together and bright red



He killed the breaker and the bright red died down. He cut the cords but hasn't taken it to anyone yet... thinking about taking it to cummins.



He said that he thought he smelled something the day before but didn't think anything cause it went away.



Anyone ever had this problem???? I wonder how often this happens?



Her father just replaced the electrical cord 2 days prior because he didn't think that the old one was working at all, but he always plugged it into the same outlet.



He was parked right next to the garage and the heater was actually smoking and bright red itself also!!! :--)

 

[illflem]

First thing to do is replace the breaker, the wires should come nowhere near red hot if it's working correctly.

More the than likely the block heater cord was damaged before it glowed and needed to be replaced. Available separately from Cummins or the dealer for about $20.

 

[Deezul1]

Also you need at least 16 gauge cord for extension cord and heavier over about 20 feet or more.

 

[David_VT]

Ironic to find this thread,

Here I sit getting ready to go back to bed from a fire call. That fire call was for a Ford Diesel that will not need to be plugged in ever again... . Very lucky family as the Ford was 2 feet from a wood garage that is tied to a home. Garage scorched but that is it... .



Good looking truck from the rear but what is left of the powercord leading from what is left of the grill seems to tell it all.....



My GFI has popped a few times on my block heater. Not every time, I wonder what that means?



After reading this thread and thinking about that poor SuperDuty I guess I will investigate my heater a bit more.....

 

[Whitmore]

Something to check for that I found out the hard way was where the cord comes thru to the front of the truck it was actually melted and stuck to the side housing of my intercooler, dont let it touch or you will have to change the cord like I did.



cheers, Kevin

 

[nickleinonen]

Originally posted by David_VT



My GFI has popped a few times on my block heater. Not every time, I wonder what that means?

i can't plug my tahoe into a gfi outlet. it blows it right away. my truck also has an oil pan heater as well as a block heater going through it.

 

[Deezul1]

When the GFI trips it is telling you that there is voltage going to ground. It can be and often is such a small amount that it is not a problem but is an indicater that something is not insulated well enough. The GFI is set to trip at a small enough amount of current bleed that humans usually cant even feel it.

 

[fkovalski]

My outlet will trip if there is road grime built up in the truck end of the plug. I'll clean the connections about once a month with BraKleen and an emory borrd. This seems to solve my tripping. I don't think I would have a condition as described in the original thread post as the breaker is quick to trip at the slightest short.

 

[illflem]

I've found that some older GFI outlets seem to get "worn out", once they've tripped a few times they seem to want to trip at nothing, they become too sensitive.



It sort of makes sense that a block heater would want to trip a GFI because the ground is also the engine ground, any stray current from the element, which is uninsulated, can travel though the coolant and show as a slight short to ground.

 

[fkovalski]

Illflem: interesting deduction- Is it possible, in reference to the original problem post, that the current draw of a block heater could cause the plug wire to become hot enough to melt it's insulation without tripping the breaker? If so, it appears that the block heater wire itself is not heavy enough. Else, any short should trip the breaker.

 

[Deezul1]

The block heater wire is designed for the load of the block heater and if it is in good condition shouldnt cause any trouble. I used a long extension cord 1 time and thought it was heavy enough to be ok but the next morning the ext cord end and block heater connection were very hot to the touch and the ext recepticle had turned brown from the heat and started to bubble. To much voltage drop caused to much resistance and created heat at the connection.

 

[BMinett]

I have 100 ft. 16 guage cord running to my truck and have never noticed any heat. I know heavier is better but should I worry if it does not get hot? I leave mine plugged in 24 hrs/day. Is this bad and should I put a timer on it?

 

[HEMI®Dart]

I have found when the block heater plug starts to get warm it's because of resistence in the extension cord/ heater cord connection. Water and other stuff will tarnish the prongs. I get the dremel tool w/ a mini wire wheel and polish the blades/prongs on the block heater cord. I take a needle file and clean the female blades on the X-cord. After I do this it's cool again for a few weeks.

 

[Hornball]

Being and electrical apprentice and being in school right now some of this information is fresh in my mind. A GFCI breaker will trip at 5ma of current loss. A GFCI works on the principle that current in the line going out should equal the current in the line coming back to the source, if the current coming back is more than 5ma less, the breaker or outlet will trip. Saying this it is very possible that a dirty connection at the plug, or a stray current to ground would cause the outlet to trip. In my opinion (which isn't worth much ) I think that the cord that was replaced was not of the proper gauge. The current draw of the block heater is pretty high around 1200-1400w, I think. It is possible that the current was high enough to melt the insulation on the small gauge cord but not over the tripping current of the breaker, since some breakers, even though rated at 15A don't trip till 17-22A.



Well sorry for being so long and probably sounding like a know it all.



Kevin

 

[illflem]

Originally posted by fkovalski

Is it possible, in reference to the original problem post, that the current draw of a block heater could cause the plug wire to become hot enough to melt it's insulation without tripping the breaker?

Not likely. For the cords to be glowing red the breaker is either bad or way too high amperage.

Originally posted by BMinett

I leave mine plugged in 24 hrs/day. Is this bad and should I put a timer on it?

If it is it sure takes a long time, mine's been plugged in 24/7 nine months of the year except while driving since 1995.

Original cord and heater.

 

[Bob Wagner]

Kevin, the block heater is only drawing 700w @120V with a 20% safety factor the current draw is only 7 amps

 

[Bigsaint]

I don't know how much this helps anyone, but I just replaced the plug on my block heater cord today. The heater had been working somedays, other days not. Always plugged into the same GFI outlet at home and using a heavy duty extension cord. Never tripped the GFI like y'all have been seeing. Replacing the plug seemed to cure the problem. As stated, my problem was sporadic so I'll have to give it a few more days of useage before I throw a party.



There's not much worse than getting up on a zero degree morning, turning to "wait to start" and seeing a coolant temp of 10F when the truck was plugged in all night .



Scott W.

 

[terrywerm]

I've had my GFI trip out also, but only when the cord was routed so that the heater plug / extension cord connection was out in the open. If it snowed or rained, enough moisture would get into the connection to cause the loss of current, tripping the GFI. I got around this by re-routing the cord and left it's end under the hood. I have to pop the hood to plug it in, but that's not that big a deal.



My old Pherd 6. 9 had the heater cord burn up a bit, but it was due to rubbing against the fuel line between the transfer pump and fuel filter. It eventually rubbed through, and created a short circuit. The wire that rubbed was the neutral wire, some of the current was returning from the heater through the block and fuel line, and back to the bare neutral wire. All of the current returned to the GFI, thus it did not trip. The block heater on that engine was only 1000W. The short circuit allowed more current to flow, but not enough to trip the 15 amp circuit breaker. Luckily, I found the problem before it started a fire..... The wires were HOT! Naturally, the first thing I did was check the breaker ... . it tripped at 16. 4 amps.



As a result, I replaced the cord and securely fastened it at various points along its route using those fancy little rubber lined cable clamps that fasten with one bolt. In addition to the clamp, and since the clamps were a little large, I placed 1" long pieces of 1/4" fuel line over the heater cord where ever it ran through one of those clamps, and also any place where there was a danger of it rubbing against something else. The fuel line ensured that the cord was clamped firmly in place once the clamp was tightened. That setup worked fine without incident for 8 years after that.



Bet you can't guess what I've done to the heater cord on every vehicle I've owned since!

 

[Deezul1]

BMinett

100 foot cord at 16 gauge might be a little light, somebody chime in here with some voltage drop specs, its been too many years since I have dealt with this stuff on a daily basis to remember it all.

There will be a drop in voltage on a long cord that is dependant on amperage draw. On a heating unit the effect will be not as much heat generated which doesnt hurt anything but the resistance at connection points will generate heat and possibly burn something up whether its the cord or your truck or trip a breaker is hard to tell. Shorten your cord to what you need and you will be better off. There are specs on this whole thing as to how much voltage drop for X number of amps for X feet of cord of X gauge.

 

[terrywerm]

I looked up the voltage drop info. It's listed in a chart indicating the maximum length of the wire based on the size of the wire and the length of the run. #16 AWG didn't even appear on the list, as the smallest listed is #14. All based on 120 VAC. I had to replace spaces with periods to get this to lay out correctly (evidently when you post, it concatenates multiple spaces. None of the figures use decimals, so just ignore the periods:



Amps... ... Watts... ... #14... ... #12... ... #10... ... . #8... ... . #6

----------------------------------------------------------------------

. . 1... ... ... ... 120... ... ... 450... ... . 700... ... 1100... . 1800... . 2800

. . 5... ... ... ... 600... ... ... . 90... ..... 140... ... . 225... ... 360... ... 575

. 10... ... ... . 1200... ... ... 45... ... ... . 70... ... . 115... ... 180... ... 285

. 15... ... ... . 1800... ... ... 30... ... ... . 47... ... ... 75... ... 120... ... 190

. 20... ... ... . 2400... ... ... --... ... ..... 36... ... ... 57... ..... 90... ... 140



According to the chart, figuring for a 600W load, you would have to use #12 wire minimum for a run of 100 feet, the same should be adequate for 700 Watts.