“All I can tell you is that I bought a very long, thicker (16 gauge, not 12?) cord in order to work in that situation for my truck”
The lower the gauge number the “thicker” the wire.
A truck block heater are usually low watt and don’t draw alot of amps, (power) so unless it is a very long cord, 16 gauge should be work.
We use the standard sink heaters in our 100 gallon tanks which are 1500 watts and need a minimum 15 amp breaker/line and are kind of expensive to run on a daily bases if needed.
Electricity doesn’t run/travel, pass through wires “smoothly” especially long ones. It meets with a certain amount of resistance. The smaller the wire the higher the resistance. Resistance equals “heat”.
A simple example using rope. Take a length of rope hold it in of your hand loosely. Have someone take the end and pull it through. Little to no “discomfort” will be felt. Do the same thing but hold it tighter and it will be comfortable, heat build up due to the “resistance” caused by your skin. Hold it even tighter and you will either get a blister from the heat and or it will cut through your skin. A longer rope will cause more continuous resistance, creating higher and higher “heat”.
Basically the same principle when a high demand electrical appliance, device like a tank heater is doing the “pulling” of the electricity through a small wire. The longer the wire the more resistance is encountered depending on the size/gauge of the wire. Also resistance/heat causes voltage/watt/amp drop off by the time the electricity reaches the other end. Something won’t work or barely work. Something will work OK but will fail prematurely. A motor will operate/turn but not with the same “strength” and or speed.
Using an inappropriate size wire with a high demand devise will cause the wire to get really hot. The breaker may or may not trip, that takes another explanation. Basically breakers trip when there is a short. Controlled/designed resistance which is how a electric toaster works does not trip a breaker.
Running a large tank heater on a long wrong size extension cord will act like the wire inside a toaster. If the breaker doesn’t trip the wire will continue to heat up, the plastic jackets on the wires and outer jacket will melt and most likely burn. When the hot and neutral/ground wire touch the breaker will trip due to them shorting on each other.
When using a plug in extension cord on a heater even an appropriate size wire the wire will get/be somewhat hot which is normal. But the greatest resistance will be found at the plug ends. These will be hotter by and large. It is important to have/use commercial grade outlets. The male and female plugs are of high quality. Or cut the mail end of the extension cord off and “hard wire” it to the power supply, the wires inside the outlet box. By pass the outlet. Very easy to do.
Depending on the length of the wire run and the quality of the extension cord no smaller than a 12 gauge should be used. IMO and experience. Depending on the length needed these can be quite expensive. It is not a good idea to plug several together. The more plugs added the more resistance will be encountered, more heat, power loss.
The longest 12/2 extension cords I could find easily only come in 100 foot lengths. Not sure it they can be bought longer.
What I did before I ran buried electric to my paddocks was to make my own long “extension cord” using direct bury 12/2 wire. like this;
http://www.homedepot.com/p/Southwire-250-ft-12-2-Gray-Solid-UF-B-W-G-Cable-13055955/202316281
Bought 15/20 amp commercial grade male and female plugs. Very easy to attach. Well, not as easy as common wire. The jacket on direct bury wire is not that easy to strip back to expose the wires inside.
Plus I saved money because I could use the same wire when I got around to trenching and burying the wire. To bury it I used my chain saw with a crappy chain on it to “cut” a slit in the ground about 8-12" deep. Pushed the wire in and foot tamped it closed. Yes, I know code “says” it is supposed to be X amount of feet below grade. But there are no code police looking over my shoulder. I know where the wire is and I am not going to dig it up by accident. Even if I did it is only 120v. If it gets cut it will only trip the breaker. No harm no foul.
I know people on the forum are adamant about not using GFC outlets. I installed them at my tank heater outlets. They kept tripping, PITA. GFC have their place but this is not one of them IMO and experience. That would take another lengthy explanation. I replaced them with a standard commercial grade outlet. Everything works just fine, no dead horses, no horses refusing to drink from the tanks, no dead employees all’s good. To each their own on this.
Whether you do some of you own minor electrical work or not it is worth having one of these simple inexpensive outlet testers. Installing new outlets is simple for anyone with very basic skills and a screw driver. High use outlets should be replaced periodically. Especially if the male plug feels loose when plugged in. Outlets do wear out. Wires can and do come loose. Plug this tester in and it will tell you if everything is OK, grounded properly. If the outlet is wired wrong it tells you what is wrong. So it is a good idea to go around the barn/house and test outlets. Test the female end of a homemade extension cord.
Electrician charge a boat load for something as simple as replacing a $5 outlet.
http://www.homedepot.com/p/GE-3-Wire-Receptacle-Tester-50542/206212329?cm_mmc=Shopping|THD|G|0|G-VF-PLA-D27E-Electrical|&gclid=CjwKEAiApLDBBRC8oICb9NvKsg0SJAD9yOHsw3bxqlYlP4iXSkCQTnCdUNHWn52JFt1NiiJxuyv3TRoCy4fw_wcB&gclsrc=aw.ds
Sorry for being so long winded. But I figure these sort of things falls under “give a person a fish they eat one day, teach a person to fish” etc.
Well, that took up my entire lunch hour. OP will you bring me a burger please.
