wiring in a new panel - MTW wire vs THHN wire

Thread Starter

dayman

Joined Jul 29, 2013
21
hello

Im wiring in a new panel and im noticing that my shop has mostly THHN wire, Im wondering if there is a preference

im installing it to an indoor panel, operating at 120 V AC and 24 V DC
 

MaxHeadRoom

Joined Jul 18, 2013
21,268
I found THHN very stiff insulation, I either use MTW or TR64 which is small gauge and thinner insulation, where it is possible to fill a wire duct up very fast with the thicker MTW's etc.
Many panels are wired with #14 which often is not necessary.
Max.
 

mcgyvr

Joined Oct 15, 2009
5,394
All depends on standards that one must apply to..
I use MTW in all my products..

THHN is a very poor choice for control panel wiring

MTW is a much better solution due to many reasons..

Or course...You didn't specific any information about what a "new panel" is..
If this is a control panel then MTW.. If a regular "breaker panel",etc.. where conduit is used then THHN may be just fine..
 

Kermit2

Joined Feb 5, 2010
4,162
For indoor use that will NEVER see any water anywhere near the wire; either will work. If in doubt use the waterproof indoor/outdoor THHN
 

Thread Starter

dayman

Joined Jul 29, 2013
21
All depends on standards that one must apply to..
I use MTW in all my products..

THHN is a very poor choice for control panel wiring

MTW is a much better solution due to many reasons..

Or course...You didn't specific any information about what a "new panel" is..
If this is a control panel then MTW.. If a regular "breaker panel",etc.. where conduit is used then THHN may be just fine..
control panel for one of our automated machines,
so then would i use THHN wire coming in from the breaker, and MTW for the rest in the control panel?
 

MaxHeadRoom

Joined Jul 18, 2013
21,268
control panel for one of our automated machines,
so then would i use THHN wire coming in from the breaker, and MTW for the rest in the control panel?
Is it predominantly 24vdc and is there high power devices?
What gauge are you currently using for control wiring?
Max.
 

Kermit2

Joined Feb 5, 2010
4,162
THHN is stiff and difficult to work with. It is very abrasive resistant and can be used around water. By using proper stress relief such as pig tail curls in the wiring and properly crimped termination sleeves for use with screw tensioned terminal blocks, THHN wire can be used inside control panels.
If there is any oil aerosol in the air, such as a manufacturing environment, THHN is resistant to it, and it will build up over the weeks and months a machine control panel is exposed. Nothing less than perfect air tight gasket sealing will keep it out.
Bottom line, if it is commercial or industrial in design, use the better armored THHN.
 
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