19 amp equipment on 30 amp overcurrent protection.

[Groundmaster]

I am looking for an answer regarding equipment that is being utilized on my site. The issue is I have a 19 amp rated piece of equipment that has a 12inch cord on it with a L5-20P plug, the cord that is on the equipment is 90degree Celsius SOW 600V #12. When the equipment is being used at full load after 1 minute it trips the 20amp breaker. I am also utilizing a 50ft #10 extension cord. This is all new equipment including the breaker, cord and the equipment itself. Does the code have an exception to use an adapter that takes you from an L5-20P to an L5-30P and utilize a 30 amp overcurrent protection device to prevent the equipment from tripping even though the equipment cord itself is #12?

 

[infinity]

If the equipment comes with a 20 amp plug then it should be able to run on a 20 amp circuit. Did you check the current draw before it tripped?

Regarding your adapter idea, many feel that the NEC stops at the receptacle so they feel that you can do whatever you want with the 30 amp circuit. It probably will void the warranty of the equipment.

 

[Groundmaster]

No we did not check the current draw unfortunately.

 

[jim dungar]

No we did not check the current draw unfortunately.

Did you check the voltage, at the end of the extension cord?

A 20A breaker should be able to carry 30A for many seconds, if not several minutes, before tripping.
It is possible that you are experiencing some significant voltage drop which is causing the equipment to draw more than normal current.

 

[rambojoe]

If i may, what is the equipment? Direct sunlight on the panel or cord by any chance? And i take it a home made s.o. cord? (Not that it matters much..)
Unfortunately a ammeter reading on the line is in your future...

 

[winnie]

I strongly agree with actually checking the current being drawn.

The idea of increasing the breaker size suggests you think you are having 'nuisance tripping' (the breaker tripping when there is no real problem) without first determining that there is no actual problem.

Check the actual current being drawn. If it more than 19A, then you need to figure out why. If the current is 19A or less then you need to figure out why the breaker is tripping too soon.

-Jonathan

 

[kwired]

Is there other load(s) on this circuit? A 20 amp breaker really should be able to handle 19 amps for a few hours minimum or maybe even hold indefinitely.

1 minute is way too short of trip time, unless breaker is seeing well over 20 amps.

 

[LarryFine]

Swap breakers with a lightly-loaded one, and check the stab/bolt while you're in there.

It's a simple, no-cost first step in process-of-elimination trouble-shooting.

 

[kwired]

Swap breakers with a lightly-loaded one, and check the stab/bolt while you're in there.

It's a simple, no-cost first step in process-of-elimination trouble-shooting.

Would need to be a very compromised stab/bolt to cause it to trip within a minute - if the load it actually drawing is 19 amps or less.

 

[retirede]

What is the equipment, exactly? If the load is mostly an induction motor, any voltage drop will cause the current to increase..

 

[CoolWill]

Turn the A/C on or use a fan at the panel?

 

[rambojoe]

Turn the A/C on or use a fan at the panel?

Ill assume you are refering to a outside panel. You dont need a fan... but
keeping the door closed seems to be difficult for some of the guys in our shop, thats the only reason i bring it up.
In the toasty Az sun (or georgia) it is a good start...

 

[petersonra]

I vote for something else being in the circuit besides the motor.

 

[kwired]

I vote for something else being in the circuit besides the motor.

We don't even know it there is a motor, just a piece of equipment presumably rated @ 19 amps.

 

[infinity]

We don't even know it there is a motor, just a piece of equipment presumably rated @ 19 amps.

The OP failed to mention what it is. If voltage drop is the issue then it probably has a motor. If it were just a resistive device voltage drop would lower the current.

 

[kwired]

The OP failed to mention what it is. If voltage drop is the issue then it probably has a motor. If it were just a resistive device voltage drop would lower the current.

Still should hold on a 20 amp breaker for longer than minute.

About has to be either pretty excessive current draw like a motor that fails to accelerate to speed or maybe something else is on the circuit.

 

[LarryFine]

Or the breaker is tripping sooner than it should, possibly from poor contact or internal weakness.

 

[tom baker]

Hopefully we will get an reply from OP

 

[jap]

I'd plug the piece of equipment directly into a dedicated outlet with good voltage if I could reach one with the 12" cord and run it at full load.
If it trips I'd call the manufacturer of the piece of equipment and get their take on it.

JAP>

 

[Groundmaster]

The OP failed to mention what it is. If voltage drop is the issue then it probably has a motor. If it were just a resistive device voltage drop would lower the current.

It is a torque motor