Sizing SO Cord to wire a portable 20HP Chop Saw

[wmeek]

I have a 20HP 230v 3phase motor on a Portable Chop Saw. Table 430.250 says to use 54A.
Using table 400.5 Column A would a #4 be correct for wiring a 20hp chop saw. This saw is on a rolling platform to be able to move around to keep from having to lift these wire ropes very high off the floor to be able to cut them. Was going to run this SO cord from a 100A Non fused disconnect. Ckt is being fed from a breaker in a panel sized per 430-52. Is this a installation code compliant.

thanks

I have a 230v - 3phase - 20HP Wire rope Saw, that is mounted on its own platform with wheels to be able to roll around close to floor to have from having to lift the cable up very high to cut it off. I am looking for some help in wiring this equipment. If you use table 430-250 for a 20hp = 54A.
54A x 125% = 67.5A I will have to use a #4 thhn Branch circuit conductor per 430-250 and
54A x 250% = 135A I will have to use a 150A Breaker per 430-6 & 430-52
Customer wants this wired with a receptacle a SO type installation so to have a little portablitiy.
54A x 125% = 67.5A Need a #2 Type SO per 400-5
The total distance from Panel to receptacle is 115'
Distance from receptacle to saw (30' of SO cord)
If this is correct sizes of conductors and breakers, What type and size of receptacle could be used . Also the problem I have had in the past is the conductors are usually to big to land in the controller of the equipment.

Thanks

 

[Cow]

You need #2 cord.

54 x 125%=67.5 amp cord

#4=60 amp
#2=80 amp

 

[wmeek]

Oops forgot the 125%

Thanks

 

[david luchini]

I don't know that I'd consider a chop saw as a continuous duty application. Depending on the time rating of the motor, the #4 may be OK.

See T430.22(E).

 

[augie47]

If it were considered anyting but Continuous the nameplate should have the rating (15 min, 5 min, etc)

 

[Cow]

I make the determination whether it's continuous or not if there is actually something keeping the motor from running for 3 hours or more. A timing relay, etc. Air compressors, chop saws, etc under normal circumstances run intermittently but there's nothing keeping them from running constantly, if say, the air line blows apart it and runs all night or someone tapes the trigger on chop saw, etc...

That's just how I look at it, may not be the right way to do it though....

 

[david luchini]

If it were considered anyting but Continuous the nameplate should have the rating (15 min, 5 min, etc)

I'm not sure I agree with this. You could certainly have a motor that is Continuous duty rated, but is being used for an intermittent duty cycle. Or you could have a 5 Minute rated motor being used for a periodic duty cycle, etc.

The duty rating of the motor doesn't necessarily correspond to Classification of Service duty, per T430.22(E).

 

[wmeek]

So I am confused here. Would a chop saw be rated for continous or non continous. It looks like to me that you would run saw for short periods of time to cut a cable. Turn it off and back on to cut another cable. I cant see it on continously. So if its not continous would a #6 conductor thhn be correct. And would a #4 Type SO cord be correct per 400-5A

 

[GeorgeB]

Even if it RUNS continuously, when not actually cutting (3 phase motor) the line current is likely between 30% and 50% of FLA. Does that enter into the decision in any way? Certainly there is more time moving, clamping, retracting, and unclamping than cutting ...

 

[jap]

I make the determination whether it's continuous or not if there is actually something keeping the motor from running for 3 hours or more. A timing relay, etc. Air compressors, chop saws, etc under normal circumstances run intermittently but there's nothing keeping them from running constantly, if say, the air line blows apart it and runs all night or someone tapes the trigger on chop saw, etc...

That's just how I look at it, may not be the right way to do it though....

Since you can't keep someone from taping a switch on or keep the contacts in a timing relay from welding together, etc....... I guess you'll have to figure everything at a continous load no matter what.

 

[Cow]

Since you can't keep someone from taping a switch on or keep the contacts in a timing relay from welding together, etc....... I guess you'll have to figure everything at a continous load no matter what.

I had to draw the line at figuring the timing relay would always work correctly....

 

[hurk27]

I have to honestly say I have never seen a 20 hp chop saw, 10 hp brick saw but not a chop saw, at least a portable one to boot.