My 3500 RW generator puts out 30 amps. I bought a power cord rated for 40 amps, thinking it would be "cheap insurance". Problem is it barely / won't start my furnace (FHA, oil). Is it possible that the power cord is too thick (too heavy duty)? Everything else runs fine. I even shut off absolutely everything in the home, but still I get the death hum of the motor trying to start. Surge rating for the generator is 4000 watts; there's no way a furnace motor needs that jolt, right? So, I'm thinking my bright idea of getting I nice thicker cable than it calls for may have been a blunder. On the other hand, the furnace is 27 years old, so maybe the motor is spent.
Amp cord overrated for generator...?
- Thread starter Nayov
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Bigger is actually better-if the cord is too long, you need a lower gauge number to carry the same current. What is the horsepower rating of the motor you are trying to start?
the cord is too long.as already said.bigger wire is better.how long is the cord?
to handle 30 amps, the cord needs to be 10 gauge. I'm gonna echo what Rand said - the generator is likely undersized for the initial startup of the motor - although one would certainly think that you have enough extra
Cord is 15'. Motor is 1/2 HP for the burner (I believe) it's a standard Beckett burner. When the fan kicks in is when the motor hums. Fan motor is small, maybe the size of a fist. But even though the burner starts, it does barely so and when the fan comes on it's game over. So basically this generator is useless during a winter event for heat, but, paradoxically, it does run my 220V well pump without drama.
Just how did you connect it? Plus is it 120 or 240? What kind of connector did you have on a power cord rated for 40 amps? Most extension cords you see are only 15-20 amps and those are regular two prong with a ground. When you get up to 30 and 40 amps, the outlet is different so unless it was a dryer cord, I'm not really sure what kind of extension cord you got.
You need to get a peak reading clamp-on ammeter and measure the draw running and at startup. Not guess.
Is your well pump 2 wires + ground to pump or 3 wires + ground to pump. The 3 wire has the capacitors next to the pump control vs in the pump. Takes less to start.
Your oil burner also has an ignition coil. Most oil burners are on a 15 amp 110V circuit.
Do you have a transfer switch?
Remember you will only get 1/2 of the 3500 watts on each side of the 220V output from your generator. Now you are at 1750 amps. Maybe a peak of 2000, but I would not count on the peak.
You need a 5K (6K peak) generator for a house with a well pump and other electric items.
Is your well pump 2 wires + ground to pump or 3 wires + ground to pump. The 3 wire has the capacitors next to the pump control vs in the pump. Takes less to start.
Your oil burner also has an ignition coil. Most oil burners are on a 15 amp 110V circuit.
Do you have a transfer switch?
Remember you will only get 1/2 of the 3500 watts on each side of the 220V output from your generator. Now you are at 1750 amps. Maybe a peak of 2000, but I would not count on the peak.
You need a 5K (6K peak) generator for a house with a well pump and other electric items.
Originally Posted By: Nayov
but, paradoxically, it does run my 220V well pump without drama.
This is because you are seeing the full capacity of the generator off of the 240V outlet. You have effectively half of the rated capacity at the 120v outlets because they are fed by one 120v leg.
You can disassemble the generator and parallel the 120v legs to get 4KW at 120v, but you could exceed the rating of the NEMA 5-20R receptacle. A 20A breaker would need to be used.
but, paradoxically, it does run my 220V well pump without drama.
This is because you are seeing the full capacity of the generator off of the 240V outlet. You have effectively half of the rated capacity at the 120v outlets because they are fed by one 120v leg.
You can disassemble the generator and parallel the 120v legs to get 4KW at 120v, but you could exceed the rating of the NEMA 5-20R receptacle. A 20A breaker would need to be used.
I would seriously get someone experienced in house electricity to look over your setup and see its connected properly with proper gauge wire.
A 15' cord may mean the generator is too close to the house and a CO problem may occur. (Problem meaning people die).
Don't back-feed. Its not legal and you obviously are not an expert in electricity.
A 15' cord may mean the generator is too close to the house and a CO problem may occur. (Problem meaning people die).
Don't back-feed. Its not legal and you obviously are not an expert in electricity.
Voltage * amps drawn = watts
Watts / voltage = amps
Watts / amperage = volts
110v * 15a = 1650w max potential draw on each 110v circuit.
At 120v * 15a = 1800w max potential draw.
A portable generator's 220 line is a 4 wire snap lock (2 110v + common + ground) and gives a max potential of 6600w of power delivery through a single circuit (220v * 30a = 6600w). A transfer switch will give you the maximum potential use of available electricity the machine can produce (4000w). That is why your well pump works great and your heater does not.
Watts / voltage = amps
Watts / amperage = volts
110v * 15a = 1650w max potential draw on each 110v circuit.
At 120v * 15a = 1800w max potential draw.
A portable generator's 220 line is a 4 wire snap lock (2 110v + common + ground) and gives a max potential of 6600w of power delivery through a single circuit (220v * 30a = 6600w). A transfer switch will give you the maximum potential use of available electricity the machine can produce (4000w). That is why your well pump works great and your heater does not.
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