Block Heater - Extension Cord

[BroncMan]

Hi All,
I hope this is the right forum. Its also not really a Bronco specific issue, but I cannot get any answers, hoping to find some help here.
I need to run a 100 foot extension cord to my Bronco's car shelter to feed the block heater.
Knowing that length creates resistance, I think of choosing a heavier gauge, e.g. 12 gauge, for that length.
- First question: does that make sense?
I also don't know how much block heaters, especially the one in the Bronco, draw.
- Second question: is the whole effort redundant because once you reach the car, the cord of the block heater itself and the
short extension needed, is most likely NOT as heavy, e.g., only 16 gauge. Is this a bottle neck that could create
a hazard and/or make the 12 gauge not necessary?
or, in other words ... what effect does the combination of two different gauges, e.g. from 12 to 16, have?

Thanks in advance

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[jkeaton]

From the owners manual:

We recommend that you do the following for a safe and correct operation:

• Use a 16-gauge outdoor extension cord that is product certified by Underwriter’s Laboratory (UL) or Canadian Standards Association (CSA). This extension cord must be suitable for use outdoors, in cold temperatures, and be clearly marked Suitable for Use with Outdoor Appliances. Do not use an indoor extension cord outdoors. This could result in an electric shock or become a fire hazard.
• Use as short an extension cord as possible.
• Do not use multiple extension cords.
• Make sure that when in operation, the extension cord plug and heater cord plug connections are free and clear of water. This could cause an electric shock or fire.
• If the block heater cord is under the hood, Do Not remove the wiring from its original location. Do Not close the hood on the extension wiring.
• Make sure your vehicle is parked in a clean area, clear of combustibles.
• Make sure the heater, heater cord and extension cord are firmly connected.
• Check for heat anywhere in the electrical hookup once the system has been operating for approximately 30 minutes.
• Make sure the system is unplugged and properly stowed before starting and driving your vehicle. Make sure the protective cover seals the prongs of the block heater cord plug when not in use.
• Make sure the heater system is checked for proper operation before winter.

Don't know if that answers your question, but that's the only guidance provided.

 

[Bucko]

If it were me, I'd pay the extra amount of money to get a heavy duty extension cord for this. The block heater to me is a large current draw amp wise. The manufacturer of the block heater should have specs on how much current (amps) it will draw. But I'd error to the high side, and get the correct (or even one step more) in gauge.

You could even make your own by buying a plug, an outlet and outlet box, and 3 wire heavy gauge wire. Just be aware that 100 feet of heavy gauge wire or pre made extension cord is going to be a lot of coin. But buying cheap will be more expensive in the way of an electrical fire.

 

[Sleddog]

For 100’ foot run at 120vac, 10 amps at 3% loss, 12 gauge. The key factor is what does the heater draw for amps. At 15 amps that number jumps to 10 gauge.

At 5 amps, 14 gauge.

And that’s copper in all cases. Aluminum gauge would be bigger in case you are thinking about making your own cable.

 

[BroncMan]

Thanks so far.
- The block heater comes with the car and is from Ford, but no specs reg. wattage.
Someone mentioned, I think, draws about 500 watts p/h.
- Yes, I'd go rather with a heavier gauge just to be on the save side.

But the main question: what happens when connecting to the existing cable of the block heater?
Is the advantage of the heavier extension useless?
I know - it's more a question about general electrical issues like ampege, resistance, wattage, etc.

 

[Bucko]

I'll assume that the block heaters wire is capable of the amp draw of the heater; otherwise they (the manufacturer) would not get the contract from Ford to have it as OEM equipment.

 

[BroncMan]

In other words - in any case, it would be a better idea to go with a heavier gauge for the extension, whatever the effect of the existing heater cord is ... it'll be always better.

If it's ok - I'd like to side track just a bit ... anyone came up with a solution for routing the block heater cable (with a short 2 foot extension) out from under the hood? With all other cars I had it was easily done through the grill. But with Broncos, with the auto open/close air intake, it's utterly impossible ... have to open the hood every time ...?

Cheers

 

[Sleddog]

The answer to your question is as short as possible for the extension cord. 100 feet is not short. Have a circuit from your main panel pulled and use a short extension cord from the new outlet to the BS.

If it is 500 watts the less than 5 amps.

 

[cprcubed]

Go with the heavier gauge just to be on the safe side. On my truck's 7.3L Powerstroke, the built in block heater is 1000-1100 watts. I used to run the extension cord to a 15-amp timer and set it to turn on 3 hours prior to when we needed to leave. I also ran the truck's wiring to an outlet receptacle mounted in the front bumper (Many folks like to use a receptacle such as the 15A Battery Charger Inlet | West Marine ... mine is from a Kenworth). Cheers!

 

[Bucko]

And as was listed in post #2 by jkeaton's list from the owners manual:

• Make sure that when in operation, the extension cord plug and heater cord plug connections are free and clear of water. This could cause an electric shock or fire.
• If the block heater cord is under the hood, Do Not remove the wiring from its original location. Do Not close the hood on the extension wiring.

Moving the plug to outside of the grill goes against what Ford recommends.

I had a 2004 Chevy 2500 with the Duramax Diesel. It had a block heater with the cord plug near the battery tray. I never needed it living in Florida, but assumed the cord was were it was so that the connector stayed dry.

 

[coopny]

- The block heater comes with the car and is from Ford, but no specs reg. wattage.
Someone mentioned, I think, draws about 500 watts p/h.

Per the manual:
The heater uses 0.4 to 1.0 kilowatt-hours of energy per hour of use

If you go on the safe side to cover the high end of range of draw, you need something that supports at least 10 amps of voltage (taking the low end of delivery of the 120V US power grid being as little as 110V, 110 volts * 10 amps = 1100 watts).

 

[CableXJ]

From the owners manual:

We recommend that you do the following for a safe and correct operation:

• Use a 16-gauge outdoor extension cord that is product certified by Underwriter’s Laboratory (UL) or Canadian Standards Association (CSA). This extension cord must be suitable for use outdoors, in cold temperatures, and be clearly marked Suitable for Use with Outdoor Appliances. Do not use an indoor extension cord outdoors. This could result in an electric shock or become a fire hazard.
• Use as short an extension cord as possible.
• Do not use multiple extension cords.
• Make sure that when in operation, the extension cord plug and heater cord plug connections are free and clear of water. This could cause an electric shock or fire.
• If the block heater cord is under the hood, Do Not remove the wiring from its original location. Do Not close the hood on the extension wiring.
• Make sure your vehicle is parked in a clean area, clear of combustibles.
• Make sure the heater, heater cord and extension cord are firmly connected.
• Check for heat anywhere in the electrical hookup once the system has been operating for approximately 30 minutes.
• Make sure the system is unplugged and properly stowed before starting and driving your vehicle. Make sure the protective cover seals the prongs of the block heater cord plug when not in use.
• Make sure the heater system is checked for proper operation before winter.

Don't know if that answers your question, but that's the only guidance provided.

Wow. I broke all of those rules. ?

 

[Major Kong]

throws a monkey wrench in the works
need to consider the exterior outlet you plan to plug the extension cord into
considerations
is that circuit sized for the job
- existing cable AWG
- existing cable length
- existing box ground fault interrupt
- what other devices are on that outlets circuit
- breaker amp rating
- is horseradish on roast beef with swiss cheese the absolute best sandwich

Bronc,
for the record I ran 10 gauge wire in a buried conduit to my garage
receptacle and timer in place for desired hours of operation

 

[SD_Zach]

It's about voltage drop and amps. The reason you want a higher gauge is so that the wire does not become a heater itself, because voltage drop is due to heat loss.

Assuming 1kW, that yields 9A; factor in an additional 20% for safety you get 11A. Get a 10 gauge cord and you should be good. Is shorter better? Yes, but that doesn't mean you can't safely go with a longer cord, it just means you need to adjust the size accordingly.

 

[point78]

I can confirm the factory block heater is under 500W. I forget the exact draw mine has, something like 430W..

Being rather low power, it does take 2-3 hours to make it worth plugging in when it’s in the single digits F. (I have it connected through a Wi-Fi plug in the garage so I can schedule or remote turn on /off the plug with my phone)

I have 3’ extension cord I ran out the front tow hook opening & zip tied. (Badlands)

Its not an outdoor one, or a cold weather one-so I’m careful to not bend the cable when it’s cold out. The insulation becomes brittle on a cheap cord when it’s really cold.

I also put a piece of paper with “block heater plugged in!” on top of the gear selector area whenever I have it plugged in so I or the wife doesn’t get in and drive off with it plugged in…

you can remote start for a few mins with the heater plugged in & it won’t hurt anything.

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