600v wire or 300v Wire

[SM Racing]

I am wiring a new bandsaw in the shop and need to feed it power. It has a 1hp 3ph motor that pulls 4amps. All of the rest of my equipment is feed with 10/4 600v Cable. Is there any reason to feed this with 600V cable? Is 300v adequate for a 30A/230v circuit?

 

[pattenp]

300V is fine. No need to use 600V.

 

[Stuart in MN]

I suppose you can find wire with 300 volt insulation, but THHN/THWN wires (like you install in conduit) and NM-B (Romex) cable are usually rated for 600 volts anyway.

 

[SM Racing]

The cable I am looking for would be what they call power cord. The last batch of stuff I bought was rated at 600V, but it seems like overkill. I think they sell 300V "powercord" as well. I have some of the regular Romex 10/3 like you refer too. Wonder why its rated differently than "power cord".

 

[big.jim]

the more popular 600v cable would probably be cheaper than 300v special order cable

 

[pattenp]

the more popular 600v cable would probably be cheaper than 300v special order cable

Around here the 300V SJOOW cord is available just as much as the 600V SOOW cord.

 

[Stuart in MN]

The cable I am looking for would be what they call power cord. The last batch of stuff I bought was rated at 600V, but it seems like overkill. I think they sell 300V "powercord" as well. I have some of the regular Romex 10/3 like you refer too. Wonder why its rated differently than "power cord".

Oh, you're talking about the flexible power cord from the saw to the wall plug - I was thinking of the wiring in the wall. Yes, depending on the particular type that will be rated at either 300 or 600 volts, but cord with 300 volt insulation will be fine for your application.

A couple typical examples: the insulation on Types SJ, SJO, or SJOW cords are rated for 300 volts, while the insulation on Types SO, SOW or SOOW cords are rated for 600 volts. What it mostly means to the average person is the SO/SOW/SOOW cords have thicker insulation that's going to be a little more durable, but the SJ/SJO/SJOW cords are still plenty good for every day use.

 

[pattenp]

The cable I am looking for would be what they call power cord. The last batch of stuff I bought was rated at 600V, but it seems like overkill. I think they sell 300V "powercord" as well. I have some of the regular Romex 10/3 like you refer too. Wonder why its rated differently than "power cord".

Totally different animal and use. You are comparing fixed wiring vs. portable cordage. The 600V in cordage is listed as "Hard Service" meaning it can take some rough use.

 

[SM Racing]

There really shouldn't be any rough service on my bandsaw, lathe, mill, etc. The "cords" are running from the junction/outlet box to the machine. Typically a fairly short distance. The machines aren't being moved around. But yes currently the lathe and mill are fed with 600V 10/4 "power cord". It has a thick black rubber insulation in addition to the individual stranded wire insulation.

 

[Charles (in GA)]

There really shouldn't be any rough service on my bandsaw, lathe, mill, etc. The "cords" are running from the junction/outlet box to the machine. Typically a fairly short distance. The machines aren't being moved around. But yes currently the lathe and mill are fed with 600V 10/4 "power cord". It has a thick black rubber insulation in addition to the individual stranded wire insulation.

Is this going to have a plug on it at the wall? Cord is not approved by the code for permanent installation/connection. If this is hard wired on both ends, you should use flex conduit with THHN wires or MC with wires in it.

Charles

 

[SM Racing]

For my mill and lathe they could be hard wired, but the bandsaw I would like to be able to roll it out away from the wall as necessary, so I would "power cord" be acceptable?

What are the definitions of a permanent installation?

 

[Charles (in GA)]

Atricle 400 of the NEC covers Flexible Cords and Flexible Cables.

400.7 Uses Permitted.
(A) Uses. Flexible cords and cables shall be used only for the following:
(1) Pendants
(2) Wiring of luminaires
(3) Connection of portable luminaires, portable and mobile
signs, or appliances
(4) Elevator cables
(5) Wiring of cranes and hoists
(6) Connection of utilization equipment to facilitate frequent
interchange
(7) Prevention of the transmission of noise or vibration
(8) Appliances where the fastening means and mechanical
connections are specifically designed to permit ready removal
for maintenance and repair, and the appliance is
intended or identified for flexible cord connection
(9) Connection of moving parts
(10) Where specifically permitted elsewhere in this Code

and

400.8 Uses Not Permitted. Unless specifically permitted
in 400.7, flexible cords and cables shall not be used for the
following:
(1) As a substitute for the fixed wiring of a structure
(2) Where run through holes in walls, structural ceilings,
suspended ceilings, dropped ceilings, or floors
(3) Where run through doorways, windows, or similar openings
(4) Where attached to building surfaces
Exception to (4): Flexible cord and cable shall be permitted to be attached to building surfaces in accordance with the provisions of 368.56(B)
(5) Where concealed by walls, floors, or ceilings or located above suspended or dropped ceilings
(6) Where installed in raceways, except as otherwise permitted in this Code
(7) Where subject to physical damage

While NEC article 670 covers Industrial Machinery (and what you have meets the def given in that section as being Industrial Machinery) one needs to refer to NFPA 79-2007, Electrical Standard for Industrial Machinery, for more information.

My use of the "permanent installation" as being not allowed by the code is probably an overstatement, as the code does allow for permanent use of cords in some situations.

For something like the bandsaw, I would install a Twistlock™ type receptacle and plug on the cord and be done with it. You want to be able to disconnect it and get it out of the way for maintenance, cleaning, etc.

 

[Falcon67]

I'd use the 600V cable because you never know when you'll need an extra 300V.

I built cords for both the heater (10-2) and my air compressor (12-3, 3.5HP). Both use a twist lock connection. The vertical compressor is not technically "permanent" as it's mounted on skid and can be rolled out of the closet with a two wheeler for service. My big lathe and mill are hardwired into lockout capable switches on a 4" box. I'd use a twist lock on the bandsaw too. Note - I bought some Cooper twisters from Amazon recently - at least 50% less cost than HD or Lowes for the same plugs/sockets. I can wait 4-5 days to save $20+.

 

[dowmace]

I'd use the 600V cable because you never know when you'll need an extra 300V.

I built cords for both the heater (10-2) and my air compressor (12-3, 3.5HP). Both use a twist lock connection. The vertical compressor is not technically "permanent" as it's mounted on skid and can be rolled out of the closet with a two wheeler for service. My big lathe and mill are hardwired into lockout capable switches on a 4" box. I'd use a twist lock on the bandsaw too. Note - I bought some Cooper twisters from Amazon recently - at least 50% less cost than HD or Lowes for the same plugs/sockets. I can wait 4-5 days to save $20+.

You can't be serious.

Are you really suggesting that he might suddenly need to run 480v through this cable?

 

[SM Racing]

Not likely at my shop. I don't even think there is 480 at the poles around here. I don't think I would be running 480 here anyways.

 

[Falcon67]

You can't be serious.

Are you really suggesting that he might suddenly need to run 480v through this cable?

Jokes don't go though the web like you think sometimes. I was implying that the cable came with 600V inside. Bummer!

 

[Charles (in GA)]

Somehow I sensed the sarcasm in that, you just left off the smiley face.

Charles

 

[Falcon67]

Good point - fixed. "220, 221 - whatever it takes."