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View Full Version : Some electrical questions....Please keep it simple answers.



Sourdough
09-12-2010, 07:23 PM
OK, In late April I moved back into the cabin that I nearly froze to death in two winters ago. And I will be toughing it out this winter here. I need to run more electric to the cabin. As now there is only one extension cord powering the cabin, and it is a 12/2 it runs the refrigerator, one light, one radio, and one laptop computer. (Note: this is working fine, and I'll leave this line as is)

So I want to run another extention cord:

First question: I have two new never used electric heaters, each one is 120v and 1,500watts. Question how much "AMPS" will I need two run both at the same time (Just the electric heaters, and nothing else)........? Thank you.

Camp10
09-12-2010, 07:35 PM
25 amps min. you can use Ohm's law..this site has a good calculator http://www.the12volt.com/ohm/page2.asp

Rick
09-12-2010, 07:40 PM
To run 3000 total watts on 120VAC you'll need a minimum of 25 amps.

Amps = Watts / volts

Amps = 3000 / 120

Amps = 25


Oops. You posted while I was typing. Sorry.

Justin Case
09-12-2010, 07:44 PM
An extension cord ? what is the source ? If its a breaker panel perhaps you could run romex,

Rick
09-12-2010, 07:47 PM
I suppose a good question would be how far do you have to run the extension cord?

Camp10
09-12-2010, 07:53 PM
What is your source sourdough? It might be a good idea to run a sub panel into the cabin.

Sourdough
09-12-2010, 08:00 PM
An extension cord ? what is the source ? If its a breaker panel perhaps you could run romex,


Thanks Rick, 25 amps I'll repel over the cliff and check the breakers, I sure hope they are 30 amp.

Justin, the service is a temporary construction 100 amp service .

Next question: a extension cord 10/3 wire 120 volt, 100 foot long. will that power the two heaters......?

Batch
09-12-2010, 08:04 PM
That math works for purely resistive loads only.

Inductive loads have a high start up demand and require you not load circuit more than 80%. So a 20 amp circuit that has any inductive loads should only have about 16 amps of load.

Sourdough
09-12-2010, 08:06 PM
What is your source sourdough? It might be a good idea to run a sub panel into the cabin.

These are skid shacks 11' X 23' (construction sheds) with no foundation. And they keep getting moved.

Sourdough
09-12-2010, 08:48 PM
Well I repelled down to the service.......the bad news is there are two 20 amp breakers. The good news is I found my chimney cap that blew off last winter, in the brush over the cliff.

Justin Case
09-12-2010, 09:05 PM
Well I repelled down to the service.......the bad news is there are two 20 amp breakers. The good news is I found my chimney cap that blew off last winter, in the brush over the cliff.

swap them for 30 or 40 amp ,,

doug1980
09-12-2010, 09:06 PM
Well I repelled down to the service.......the bad news is there are two 20 amp breakers. The good news is I found my chimney cap that blew off last winter, in the brush over the cliff.

Not sure what the temp 100 amp box looks like but if there is room you could just buy a 30 amp breaker and put it in. Or replace one of the 20 amp breakers with a 30 amp.

crashdive123
09-12-2010, 09:07 PM
Well I repelled down to the service.......the bad news is there are two 20 amp breakers. The good news is I found my chimney cap that blew off last winter, in the brush over the cliff.

Did you notice if there was a Beretta down there?:innocent:

Batch
09-12-2010, 09:39 PM
12/2 ain't suitable for upgrading to 30 or 40 amp service.

oly
09-12-2010, 10:16 PM
I myself have a minimum standard to prevent forest fires.
@ 50' or less of wire
14 gauge @ 15 amp.
12 gauge @ 20 amp.
10 gauge @ 30 amp.
8 gauge @ 40 amp.
Better safe than sorry.

Sourdough
09-12-2010, 11:10 PM
I have 4 extention cords that are special for the generators, they are 10/3 30amp and at the end of one it splits out into four (110/120) 20amp outlets for construction power tools. What I want to do is use them and run one 1500 watt heater off each side. But I am going to have to hard wire them into the box, as the female 30amp twist-lock is expensive.

Alaskan Survivalist
09-13-2010, 12:15 AM
"Boots in the Field, Baby. Boots in the Field" Just plug it in and see if it works.

Is that simple enough?

kyratshooter
09-13-2010, 05:43 PM
If you are hard wiring the heaters in I would want a switch box on the line to shut the power off on that circuit.

I was running the same setup last year and melted down a 30 amp plug mid-winter at full draw. If i had not had a shut-off in the line I would have burned down.

Ole WV Coot
09-15-2010, 07:40 AM
Did you notice if there was a Beretta down there?:innocent:

Can't leave it alone can you? It is still MIA and haven't had a chance to check the attic, workshop or garage yet.:blushing:

Sourdough
09-15-2010, 08:17 AM
If you are hard wiring the heaters in I would want a switch box on the line to shut the power off on that circuit.

I was running the same setup last year and melted down a 30 amp plug mid-winter at full draw. If i had not had a shut-off in the line I would have burned down.

You have to understand it is 4.0 HOURS driving time from Anchorage to here round trip. If I had an electrician come down it could easily run $600.00 plus for 1/2 Hr. work.

tipacanoe
09-15-2010, 07:15 PM
Wouldn't a small kerosene heater work better for you? Get more heat, your electrical system wouldn't be on the edge. I don't know how close you are to K1 but I think that is the route I would take. I have a Heavy duty 50 foot cord for my generator, and the package says its rated for only 15 amps. If you use nomex your rating will be smaller, as you have less surface than with the stranded cable. On some of our cables on the ships a 400 mcm cable will have up too 1500 strands per conductor just for the amps rating.

kyratshooter
09-15-2010, 10:35 PM
You have to understand it is 4.0 HOURS driving time from Anchorage to here round trip. If I had an electrician come down it could easily run $600.00 plus for 1/2 Hr. work.

I'm just talking about a shut off switch in the line where you can cut off the flow before it reaches the heaters. You don't need an electrician, just a switch.

Sourdough
09-15-2010, 11:20 PM
I'm just talking about a shut off switch in the line where you can cut off the flow before it reaches the heaters. You don't need an electrician, just a switch.


I guess I am NOT understanding, sorry. There is no wiring in the cabin, only one 10/3 extension cord. If I run another extension cord off of a different breaker, I think it should be OK. What am I missing here.....? I really do want to understand.

Rick
09-16-2010, 07:23 AM
Sourdough - A few things to consider on this set up.

1. Be certain to check the plugs on both ends. The resistance of the cord (length, gauge, etc.) produces heat and the plugs will get the hottest because they are not a solid connection. The plugs will probably be warm to the touch at both ends but they should be so hot that they are uncomfortable to touch. If they are, then you have a problem. If one plug is hot and the other warm then you have a bad connection at the hot plug. That bad connection might be inherent in the male/female connection.

2. Make certain the ground is connected on the feeder outlet and it might not be a bad idea to use a GFCI. The heaters might have double insulated plugs but make certain the ground is connected anyway. You don't want to wake up some night to find Bruno G. Bear has been trying his paws at rewiring your extension cord. That connected ground wire can save you a lot of headaches. And the GFCI might save you some problems if a pin hole develops in the insulation and you decide to touch the cord for whatever reason.

3. Test it before you need it. Just sayin'.

kyratshooter
09-17-2010, 03:42 PM
I guess I am NOT understanding, sorry. There is no wiring in the cabin, only one 10/3 extension cord. If I run another extension cord off of a different breaker, I think it should be OK. What am I missing here.....? I really do want to understand.

You are running 10/3 romex or an extension cord?

Like Rick just said, the cord is going to get hot at the 100 foot length. A lot of resistance in that much line. If the heater you hard wire in shorts out or the line gets too hot you may not be able to run down to the breaker box and unplug before the fire starts. I shutoff switch in the line may save your life.

http://www.lowes.com/SearchCatalogDisplay?storeId=10151&langId=-1&catalogId=10051&N=0&newSearch=true&Ntt=30+amp+switches

It may not matter, or I may be misunderstanding the situation.

I know that when I have used these setups I was much more at ease after I put a breaker where I could get to it. I set my first cabin up the way you are talking the first year I was there. It was on a 30 amp temp feed while I built. The 30 amp box went into my workshop after I got the wiring completed and did not need it any more.

Sourdough
09-17-2010, 03:50 PM
Well.........I have 98 feet of 10/3 direct bury line leftover from the water well install. Maybe I can but a temporary breaker box in the Goose Barn and string short extention cords from there.

Rick
09-17-2010, 04:42 PM
I didn't mean to imply the cord would get hot. Frankly, I don't think it will. 10/3 is pretty robust. But the plugs might since that isn't a solid connection. They will be warm I'm sure but they shouldn't be too hot to touch.

If you did have some kind of a problem you should be able to unplug the heaters from the cord.

I run power tools and lights on 100' of 12/2 stranded extension cords all the time and I've never had a problem. I'm not pulling the wattage you will be but 10/3 solid is pretty substantial cord.

Sourdough
09-17-2010, 04:59 PM
I didn't mean to imply the cord would get hot. Frankly, I don't think it will. 10/3 is pretty robust. But the plugs might since that isn't a solid connection. They will be warm I'm sure but they shouldn't be too hot to touch.

If you did have some kind of a problem you should be able to unplug the heaters from the cord.

I run power tools and lights on 100' of 12/2 stranded extension cords all the time and I've never had a problem. I'm not pulling the wattage you will be but 10/3 solid is pretty substantial cord.

The 10/3 can leave the box as 220/30A and when it reaches the cabin it can be split out into two 110/120 20A and that would offer a 5A cushion if each heater needs 15A at full load. I guess the other option is find a electric heater that is 220V

Sourdough
09-17-2010, 05:05 PM
Rick, I should also point out that these Extention Cords have four (4) prong twist-lock conectors. They are 220V/30A

Rick
09-17-2010, 05:31 PM
That's much better then. The attack geese should be very happy.

kyratshooter
09-17-2010, 09:23 PM
While you are doing all this be sure and tie a magnet on a string and drag it behind you.

You might find the Baretta

:m107: