Do I need to size my wire for the FLA plate reading?

[remspot]

We design a small piece of equipment that uses a control box that has a 16.2A FLA rating. The machine runs constantly at around 1.5-2A. Inside the control box is a 10A breaker. The control box is designed to plug into a wall outlet which is typically 15A. Do I need to run a 20A cable with the FLA being 16.2A or does the 10A breaker allow me to stick with the 15A wall outlet rating? So can I just use a 15A rated cord?

 

[infinity]

Maybe I'm not understanding the setup but how can the FLA be 16.2 amps when there is a 10 amp CB feeding it?

Welcome to the Forum.

 

[sameguy]

This sounds like you fall under the manufacturing rules not the NEC.

 

[tom baker]

We get a lot of questions here on power supplies, control panels, ect that are outside the scope of the NEC. The NEC is for premise wiring, IE the receptacle that you plug into. Your question is more appropriate for a UL or NTRL agency. Equipment such as what you are describing is typically required to be listed under UL 508A.
However the NEC does cover equipment that is not really premise wiring.. IE GFCIs for vending machines, luminaires, extension cords...

 

[remspot]

Maybe I'm not understanding the setup but how can the FLA be 16.2 amps when there is a 10 amp CB feeding it?

Welcome to the Forum.

The FLA is from two small conveyor motors, two stepper motors, DC power supply and a thermal printer. The FLA was calculated on these items but measuring full out running of everything, it only reaches about 2A. The design always had a 10A breaker so it was left alone which will protect the system sufficiently.

I understand this falls under the UL 508A but I don't have to much knowledge of my scenario and was wondering if someone here could advise on the power cord.

Thanks guys.

 

[remspot]

Or can we place 10A on the nameplate for FLA because it is protected to that from the internal breaker?

 

[jumper]

Or can we place 10A on the nameplate for FLA because it is protected to that from the internal breaker?

10A is the rating of your internal breaker. The nameplate should reflect it but that is not FLA.

FLA is used for motor ampacity only. Your total FLA/FLC cannot be larger than your OCP/breaker.

 

[kwired]

What is this control box?

Sounds like an already assembled component that you are putting on your equipment and not something you are building.

Was it built specifically for your application or is it general purpose assembly that you are fitting to your application?

Is your final product a listed assembly?

NEC can apply to such a machine if it isn't otherwise covered by a listing.

 

[Jraef]

We design a small piece of equipment that uses a control box that has a 16.2A FLA rating. The machine runs constantly at around 1.5-2A. Inside the control box is a 10A breaker. The control box is designed to plug into a wall outlet which is typically 15A. Do I need to run a 20A cable with the FLA being 16.2A or does the 10A breaker allow me to stick with the 15A wall outlet rating? So can I just use a 15A rated cord?

I find that highlighted part difficult to believe... just the no-load current on a motor rated 16.2A FLA is going to be higher than 1.2-2A, let alone if this machine is actually DOING something.

Or is that 16.2A the TOTAL amps rating of the entire machine? For that you should use the term “Full Load Current”, because FLA is reserved for use in describing a MOTOR FLC rating. To give you an example, UL 508a for control panels requires a label on the outside giving the user the FLC of the ENTIRE panel components combined, plus the FLA of the largest motor controlled by that panel (if any), plus the Short Circuit Current Rating of the assembly as a whole.

So if you meant the FLC of the panel is 16.2A, then THAT is the value that you must size the circuit for that feeds it. The fact that you have a 10A breaker feeding a panel that can ostensibly draw 16.2A is your own business in that you may have to live with the nuisance tripping. But from an NEC standpoint, what you observe as the current draw, the 1.5 to 2A, is irrelevant.

 

[Dennis Alwon]

The 16.2 might be the maximum rating of the control box and has nothing to do with the amperage of the units.

 

[remspot]

What is this control box?

Sounds like an already assembled component that you are putting on your equipment and not something you are building.

Was it built specifically for your application or is it general purpose assembly that you are fitting to your application?

Is your final product a listed assembly?

NEC can apply to such a machine if it isn't otherwise covered by a listing.

This is built specifically for our application. The final product has no UL listing or requirements by the customer it is sold to.

 

[remspot]

I find that highlighted part difficult to believe... just the no-load current on a motor rated 16.2A FLA is going to be higher than 1.2-2A, let alone if this machine is actually DOING something.

Or is that 16.2A the TOTAL amps rating of the entire machine? For that you should use the term “Full Load Current”, because FLA is reserved for use in describing a MOTOR FLC rating. To give you an example, UL 508a for control panels requires a label on the outside giving the user the FLC of the ENTIRE panel components combined, plus the FLA of the largest motor controlled by that panel (if any), plus the Short Circuit Current Rating of the assembly as a whole.

So if you meant the FLC of the panel is 16.2A, then THAT is the value that you must size the circuit for that feeds it. The fact that you have a 10A breaker feeding a panel that can ostensibly draw 16.2A is your own business in that you may have to live with the nuisance tripping. But from an NEC standpoint, what you observe as the current draw, the 1.5 to 2A, is irrelevant.

Two 3-phase 1/4 HP motors are .52A a piece, two 5 phase steppers are 4.5A a piece, printer is 2.5A and DC power supply is 3.5A. 16A is the total of the system. We never see a nuisance tripping issue with our acc/dec 3 phase inverter or stepper drivers all running full speed or turning on.

 

[Jraef]

Two 3-phase 1/4 HP motors are .52A a piece, two 5 phase steppers are 4.5A a piece, printer is 2.5A and DC power supply is 3.5A. 16A is the total of the system. We never see a nuisance tripping issue with our acc/dec 3 phase inverter or stepper drivers all running full speed or turning on.

OK, I believe you now with the detail added. Most likely not everything will run at the same time. But technically, if the panel says the total load is 16.2A, then the NEC requires that the circuit be sized for that, regardless of the fact that it has a 10A breaker for the entire thing. Without putting a lot of effort into it, I would just run #12 and be done with it.

 

[kwired]

OK, I believe you now with the detail added. Most likely not everything will run at the same time. But technically, if the panel says the total load is 16.2A, then the NEC requires that the circuit be sized for that, regardless of the fact that it has a 10A breaker for the entire thing. Without putting a lot of effort into it, I would just run #12 and be done with it.

I thinking, but haven't had OP confirm yet, that this may be some sort of controller rated for up to 16 amps, but he is using it for less overall load. Sort of a generic controller more so than something specifically tailored for what he is using it for.

Similar but simpler explanation would be a small motor controlled by a NEMA size 1 contactor, when a size 00 would otherwise be sufficient.

 

[Russs57]

Things aren’t adding up for me. A 3 phase 1/4 HP motor rated at 0.52 amps implies a 440/480 supply. Yes a VFD running off wall receptacle might run the motor but current draw won’t be 1/2 amp.

Maybe I read things wrong and supply voltage is 480. In that case I can’t see the printer drawing that much current.

 

[kwired]

Things aren’t adding up for me. A 3 phase 1/4 HP motor rated at 0.52 amps implies a 440/480 supply. Yes a VFD running off wall receptacle might run the motor but current draw won’t be 1/2 amp.

Maybe I read things wrong and supply voltage is 480. In that case I can’t see the printer drawing that much current.

He never said what voltage/number of phases the "wall outlet" is.

Between two small conveyor motors, two stepper motors and the printer total amps is only 2 amps. Seems about right for what has been described to me. If 480 volt three phase supply that is only about 1662 VA.

 

[remspot]

Things aren’t adding up for me. A 3 phase 1/4 HP motor rated at 0.52 amps implies a 440/480 supply. Yes a VFD running off wall receptacle might run the motor but current draw won’t be 1/2 amp.

Maybe I read things wrong and supply voltage is 480. In that case I can’t see the printer drawing that much current.

I mentioned that we use a 3-phase VFD to use 120VAC to control the speed of the 3-phase motor. .52 amp is the nameplate amperage on the 3-phase motor casing.

 

[remspot]

He never said what voltage/number of phases the "wall outlet" is.

Between two small conveyor motors, two stepper motors and the printer total amps is only 2 amps. Seems about right for what has been described to me. If 480 volt three phase supply that is only about 1662 VA.

Wall outlet is 120VAC single phase.