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Wire Size for Jointer

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bad_idea

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I am bringing home a Porter No. 350 6” jointer tomorrow. It has a three horse electric motor on it, set up for 240v. I am unsure the amp draw on the machine, data plate is AWOL on the motor. Motor has drip ports for oiling the bearings, definitely older.

I plan to run a dedicated circuit for it. I have a 90 amp sub panel in the garage. Garage is stick built, no wall coverings - wired with Romex. I am hoping to get away with 12/2 romex on a 20 amp breaker, because I have it on hand. I did a quick google search and came up with different amp draws for a 3 hp motor - between 14-17 amps. I can plug it into my welder socket to test for actual amp draws.

My question is: what are the maximum amps a motor can draw on a 20 amp circuit? Run for the circuit will be ~60’ from the panel. Really don’t want to pay for 10/2 romex if I can help it.
 
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mm08822

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I assume this will be portable equipment, meaning cord and plug connected.
In that case, as a non-continuous load, it could draw 20A under load and not trip the cb. I don't expect a jointer to trip a cb on start-up as it should get right up to speed as it is unloaded.

If it happened to be permanently connected to its own circuit, then by code it could be up to 16A. (I would still use the #12 even if it were 17A.)

My Delta 6" jointer nameplate is 14A @115V and has never tripped a 20A cb - FWIW.
 
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dave*99

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bad_idea said:
I am bringing home a Porter No. 350 6” jointer tomorrow. It has a three horse electric motor on it, set up for 240v. I am unsure the amp draw on the machine, data plate is AWOL on the motor. Motor has drip ports for oiling the bearings, definitely older.

I plan to run a dedicated circuit for it. I have a 90 amp sub panel in the garage. Garage is stick built, no wall coverings - wired with Romex. I am hoping to get away with 12/2 romex on a 20 amp breaker, because I have it on hand. I did a quick google search and came up with different amp draws for a 3 hp motor - between 14-17 amps. I can plug it into my welder socket to test for actual amp draws.

My question is: what are the maximum amps a motor can draw on a 20 amp circuit? Run for the circuit will be ~60’ from the panel. Really don’t want to pay for 10/2 romex if I can help it.
Click to expand...

Hmmm. 6" jointer with a 3 HP motor. Seems like way more power than needed. You said the motor nameplate is missing. I expected a 1 HP motor on this size machine. I found this thread and it got me thinking - are you getting a 3 phase motor, not 3 HP?

 
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Firebrick43

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dave*99 said:
Hmmm. 6" jointer with a 3 HP motor. Seems like way more power than needed. You said the motor nameplate is missing. I expected a 1 HP motor on this size machine. I found this thread and it got me thinking - are you getting a 3 phase motor, not 3 HP?

Click to expand...
My powermatic model 60 8” jointer only has 1.5hp and does fine.

The op should definitely pop the lid off the peckerhead of the motor and take a pic of the connections.
 
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wyliesdiesels

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bad_idea

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I didn’t delve into the machine too far. Picking it up this afternoon and will investigate. Owner said it has a 3hp motor on it. He plugged it into a 240v outlet in his 2 car garage (private residence), don’t imagine he has three phase service.
 
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dave*99

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bad_idea said:
I didn’t delve into the machine too far. Picking it up this afternoon and will investigate. Owner said it has a 3hp motor on it. He plugged it into a 240v outlet in his 2 car garage (private residence), don’t imagine he has three phase service.
Click to expand...
That's good news. As stated earlier 20A on 12ga wire will run it. If it's really 3 HP it won't be working hard.
 
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bad_idea

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mm08822 said:
I assume this will be portable equipment, meaning cord and plug connected.
In that case, as a non-continuous load, it could draw 20A under load and not trip the cb. I don't expect a jointer to trip a cb on start-up as it should get right up to speed as it is unloaded.

If it happened to be permanently connected to its own circuit, then by code it could be up to 16A. (I would still use the #12 even if it were 17A.)

My Delta 6" jointer nameplate is 14A @115V and has never tripped a 20A cb - FWIW.
Click to expand...

I am confused on what you are driving towards. I understand the NEC definition of 'continuous load' as anything that draws amps for 3 hours or more. I do not understand how a plug and socket or hardwire setup would have any effect on its status as a 'continuous load'.

The jointer currently has a plug on the end of it, but I am planning to hardwire it. I have a couple disconnect switches in a drawer, and no need to move this thing.
 
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mm08822

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bad_idea said:
I am confused on what you are driving towards. I understand the NEC definition of 'continuous load' as anything that draws amps for 3 hours or more. I do not understand how a plug and socket or hardwire setup would have any effect on its status as a 'continuous load'.

The jointer currently has a plug on the end of it, but I am planning to hardwire it. I have a couple disconnect switches in a drawer, and no need to move this thing.
Click to expand...
I was explaining how you should size the circuit to be NEC compliant if it were a permanent hard-wired load instead of some random thing that gets plugged into the closest receptacle occasionally.

Since you are hard-wiring it, the conductors should be rated for 125% of motor FLA. Looks like the 3hp motor was overkill on this jointer but it's common that a spare motor gets volunteered to work and made to fit.
12's will be fine. It this motor ever failed, I doubt you would throw another 3hp on it.
 
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