Page 1 of 2 12 LastLast
Results 1 to 10 of 13

Thread: Control Panel wire

  1. #1
    Join Date
    Aug 2009
    Posts
    4

    Control Panel wire

    Have a current project that requires the use of 3/0 AWG for 480V power distribution. I haven't built a panel using this size wire and bend radius is a concern. I was looking into using a high flex wire, but after receiving a sample, I think THHN may be a better option. THHN holds it's shape better after bending. Also leaning towards THHN after reading some posts requiring crimp lugs specifically made for fine stranded cable.
    While on the subject of wire, also interested what type wire most panel shops use for:
    1. 480V distribution
    2. 24VDC control
    3. PLC I/O logic
    We currently use THHN for 480/240/120VAC, UL1007 or TFFN for 24VDC logic and curious what others commonly use.
    Any input is greatly appreciated.

  2. #2
    Join Date
    Aug 2004
    Posts
    11,166
    virtually everyone in the business uses mostly MTW.
    Bob

  3. #3
    Join Date
    May 2012
    Location
    North Carolina
    Posts
    59
    For the newer (smaller) PLC's I am using 18awg MTW to go to the IO cards, When my IO leaves the panel I run 16awg MTW in conduit out to inputs and outputs.

    I use MTW that has no clear covering over the wire insulation (it may all be this way). The insulation tends to be a little thicker that is why I don't run the 16 awg to the input cards. I always go to terminal blocks from the I/O card.

  4. #4
    Join Date
    Jul 2006
    Location
    San Francisco, CA, USA
    Posts
    3,592
    I used THHN for power wiring for a long time, until I discovered Flexible Insulated Bus. It's a lot more expensive from a conductor cost standpoint, but that is more than made up for in reduced assembly time and the ability to make tight bends and reduce panel space. The thing is, it is a "UL Recognized" product, not UL listed, so if you are a UL panel shop that means you have to add it to your procedure, which also costs money (and time).

    http://www.erico.com/products/EriflexFlexibles.asp

    For control wiring, I used MTW also. Sometimes on specs I was required to use SIS, you want to avoid those jobs, it's a PITA.
    __________________________________________________ ____________________________
    "Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
    — Kilgore Trout (via Kurt Vonnegut)

  5. #5
    Join Date
    Aug 2004
    Posts
    11,166
    Quote Originally Posted by Jraef View Post
    I used THHN for power wiring for a long time, until I discovered Flexible Insulated Bus. It's a lot more expensive from a conductor cost standpoint, but that is more than made up for in reduced assembly time and the ability to make tight bends and reduce panel space. The thing is, it is a "UL Recognized" product, not UL listed, so if you are a UL panel shop that means you have to add it to your procedure, which also costs money (and time).

    http://www.erico.com/products/EriflexFlexibles.asp

    For control wiring, I used MTW also. Sometimes on specs I was required to use SIS, you want to avoid those jobs, it's a PITA.
    Actually, if you use table 28 ampacities, you can use the erico flexible bus w/o a procedure change as it is also recognized as AWM. the procedure change is required to use the expanded ampacities Erico claims byond table 28.
    Bob

  6. #6
    Join Date
    Aug 2004
    Posts
    11,166
    Quote Originally Posted by travish View Post
    For the newer (smaller) PLC's I am using 18awg MTW to go to the IO cards, When my IO leaves the panel I run 16awg MTW in conduit out to inputs and outputs.

    I use MTW that has no clear covering over the wire insulation (it may all be this way). The insulation tends to be a little thicker that is why I don't run the 16 awg to the input cards. I always go to terminal blocks from the I/O card.
    what size OCPD are you using to protect that 18 awg wire?

    mtw comes in a couple different flavors, although it all seems to be 105C AWM dual rated these days.

    the transparent coating is found on THHN to make it easier to pull in conduit.
    Bob

  7. #7
    Join Date
    Aug 2009
    Posts
    4
    Thank you all for the response.

    We used MTW for DC control circuits, then changed to UL1007 because it's easier to work with and takes up less space. And as we all know, panel space is usually at a premiun, especially if the mechanical designers get any input. UL1007 is rated for 300V, but when DC control must run with 480V, we use TFFN.

    I did find the Flexi-Bus that Jraef also posted and think it'll be a great alternative to standard wire. The price of the busbar isn't too bad, but the tooling price is very high. Is it really necessary, especially the jig for drilling?

    Bob referenced Table 28 in regards to ampacity. Is that a UL508 table?

  8. #8
    Join Date
    Aug 2004
    Posts
    11,166
    Quote Originally Posted by mcs View Post
    Thank you all for the response.

    We used MTW for DC control circuits, then changed to UL1007 because it's easier to work with and takes up less space. And as we all know, panel space is usually at a premiun, especially if the mechanical designers get any input. UL1007 is rated for 300V, but when DC control must run with 480V, we use TFFN.

    I did find the Flexi-Bus that Jraef also posted and think it'll be a great alternative to standard wire. The price of the busbar isn't too bad, but the tooling price is very high. Is it really necessary, especially the jig for drilling?

    Bob referenced Table 28 in regards to ampacity. Is that a UL508 table?
    Table 28 correlates cross sectional area of the conductors to allowed ampacity in UL508a.

    BTW, UL508 is not the same thing as UL508a.
    Bob

  9. #9
    Join Date
    Jul 2006
    Location
    San Francisco, CA, USA
    Posts
    3,592
    Quote Originally Posted by mcs View Post
    ...
    I did find the Flexi-Bus that Jraef also posted and think it'll be a great alternative to standard wire. The price of the busbar isn't too bad, but the tooling price is very high. Is it really necessary, especially the jig for drilling?...
    I used a vice... We adapted a vice to have smooth jaws so as the not impart the cross hatch pattern onto the exposed plates. We welded some smooth angle iron into the jaws, which also raised the jaw lip up a little so that you can make tight right angle bends by pounding it over with a leaded plastic mallet (rubber was too soft). By the way, drill after bending, and leave a little extra to cut off straight afterward, the plates move and stretch. If you do a lot of work though, you will want to buy the hole punch, it's much much faster and cleaner.
    __________________________________________________ ____________________________
    "Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
    — Kilgore Trout (via Kurt Vonnegut)

  10. #10
    Join Date
    Aug 2004
    Posts
    11,166
    Quote Originally Posted by mcs View Post
    Thank you all for the response.

    We used MTW for DC control circuits, then changed to UL1007 because it's easier to work with and takes up less space.
    Is UL1007 listed in the table of stuff you are allowed to use in a 508a panel?
    Bob

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •