Lee 20 lb furnace draw?

[CoolHandMoss]

I do my casting in a garage without power run to it. To power my lead pot I have a 50' extension cord run from a ground-fault outlet on the outside of the house to a splitter that I plug my 10 lb pot in to. This works fine. I want to get a 20 lb pot but I am concerned about the draw. When plugging in high draw appliances like a compressor to the extension cord I have tripped that breaker before. I figure there is no way to know without trying but does anyone have any idea what kind of chance I would have of being able to run the 20 lb pot on this setup?

[imashooter2]

A 14 gauge cord will easily handle the 700 watt pot with plenty of safety margin.

ETA: 700 watts at 120 volts is 5.83 amps. A ten amp circuit is adequate if you don’t have much else on the breaker.

[kevin c]

I know from personal experience that a 15 amp circuit will trip if my ProMelt topped with a 4-20 feeder (both PID controlled) and my 1100 watt mold heating hot plate all cycle on at the same time. Now I use an extension cord running through the house from an outlet on another circuit out to the deck where I cast.

[StuBach]

I have my ProMelt1 hooked up to my ceiling outlet cord reel in my garage. Run my hot plate, fan, light and pot off of it with no issues. That same outlet also feeds my overhead lighting but that’s negligible since their all LED shop lights. 15amp circuit with “cheap” cord reel from Amazon and - small power strip.

[sharps4590]

Amps times volts equals watts. None of us are going to get away from it. By NEC one is allowed to load to 80% of the capacity of a circuit. It isn't a law it's just how electricity works. I was an electrician/contractor for 43 years and I certainly don't go around calculating the load on my circuits and neither does anyone else. You do that mentally when you're wiring the house...or I always did, except where loads and circuitry are specified. One can exceed that for a while but heat builds up, increasing resistance, decreasing voltage which increases amperage and exceeds the rating of the breaker....and "pop"....you're off to reset the breaker.....once it cools.

At the 80% allowed, 1100 watts is over half a 20 amp circuit and if you're on a 15 amp circuit it's almost 3/4 the allowed 80% capacity of your circuit.

[Bobbers]

Sharps4590 brings up good information.
As far as extension cords go the heavier the better and the shortest length to get the job done.

[imashooter2]

Or you can just run a 14 gauge 50 foot extension cord off a 10 amp circuit and have plenty of safety margin for the 700 watt Lee pot you asked about.

[CoolHandMoss]

So if it trips I could possibly just get a heavier cord? I haven't figured out yet which breaker the outlet is on. Pretty sure it's at least 20. I only have a few 15s.

[imashooter2]

No. If the breaker trips it will be because something other than the pot is running on the circuit. A too small cord will restrict current to the pot (think of a too small pipe restricting flow) and might overheat.

The Lee 20 pound pot pulls under 6 amps. That isn’t a lot.

[uscra112]

He means the cord will overheat.

[JonB_in_Glencoe]

I do my casting in a garage without power run to it. To power my lead pot I have a 50' extension cord run from a ground-fault outlet on the outside of the house to a splitter that I plug my 10 lb pot in to. This works fine. I want to get a 20 lb pot but I am concerned about the draw. When plugging in high draw appliances like a compressor to the extension cord I have tripped that breaker before. I figure there is no way to know without trying but does anyone have any idea what kind of chance I would have of being able to run the 20 lb pot on this setup?

So if it trips I could possibly just get a heavier cord? I haven't figured out yet which breaker the outlet is on. Pretty sure it's at least 20. I only have a few 15s.

No. If the breaker trips it will be because something other than the pot is running on the circuit. A too small cord will restrict current to the pot (think of a too small pipe restricting flow) and might overheat.

The Lee 20 pound pot pulls under 6 amps. That isn’t a lot.

A GFCI trip means there is a Ground Fault.

from littelfuse.com
A ground fault is an inadvertent contact between an energized conductor and ground or equipment frame. The return path of the fault current is through the grounding system and any personnel or equipment that becomes part of that system. Ground faults are frequently the result of insulation breakdown.

Also, I've had GFCI trips from extension cord connections in moist, outside environments (ie: dewy grass).

[imashooter2]

A GFCI trip means there is a Ground Fault.



Also, I've had GFCI trips from extension cord connections in moist, outside environments (ie: dewy grass).

Indeed. I assumed he meant the circuit breaker tripped, not the GFI.

[sharps4590]

In 43 years in the trade I've never seen a "10 amp" breaker, for a "10 amp circuit", not in a residential or commercial application. 15 is the minimum allowed by code unless it's integral to a piece of equipment. I have heard a lot of people say they have a "10 amp" breaker when they're looking at the 10,000 AIC that's printed on all residential grade breakers. Commercial breakers are generally 20,000 AIC and Industrial/heavy commercial breakers can be whatever the engineer specifies for the equipment being operated, depending on the voltage.

GENERALLY, a 15 amp. circuit is/was used for lighting circuits and 20 amp. for receptacle circuits. With the advent of LED's a 15 amp circuit can just about carry the entire lighting load of an 1800 to 2000 sq. ft. house.

I have replaced a truck load of GFCI receptacles because they A) failed to trip or wouldn't trip or, B) wouldn't reset and NOT because there was a fault on the line. They're an electro-mechanical device. They will fail.

It's quite easy to calculate your loads. Just add up the wattage of the devices plugged into your particular circuit. A 20 amp circuit calculates to 2400 watts. 80% of that is 1920 watts. A 15 amp circuit is 1820 watts and 80% of that is 1456 watts. The 80% is probably occasionally exceeded by some smallish amount by all of us and the circuit breaker will hold, often for quite a while. With something like a lead furnace the load is continuous until the melt temp is reached then it becomes intermittent, the thermo or PID kicks it off and on. As alluded to in my earlier post, there is also a time factor involved. The longer a load is applied to a circuit the more the conductor warms up, as does the breaker, (breakers trip trip on heat whether caused by a fault or overload), resistance increases, it becomes harder for the volts to push the amps through the wire. Amps and volts are directly proportional, so far as I know. Speaking in simple terms, if the resistance causes the voltage to drop 20%, the amperage increases 20%. Anyway, if you're tripping a breaker just add up the watts of what is on that circuit and unplug or turn off something.

Many kitchens are underwired and the same thing applies there. You can't operate 4000 watts of toaster, griddle and coffee pot on a circuit wired for basically half that. Nor can you operate a 1500 watt space heater on a 20 amp., 120 volt circuit already carrying 1500 watts of load.

[Wis Tom]

I second sharps4590, on GFCI, they fail, but code calls for them, on all outside circuits.

[sharps4590]

NEC calls for them in all outside locations, ANY counter served areas, not just within 6 feet of a water source as the old codes did, bathrooms and unfinished areas....which includes garages, unfinished basements, crawl spaces, attics and probably a lot of our shops. Newer Codes might expand on that but, that was the last NEC I was familiar with and working under.

And, of course that is dependent upon codes being enforced. There is still probably a majority of the US where there is no Code enforcement. There is none in the county where we liv but there is in town.