Lightning_Strikes_Twice
Member
Anyone ever use MTW? I am wondering what restrictions for the terminal side there are? If i am taking this to a breaker is there a particualr type of lug for this wire, or will it behave like THHN?
MTW Wire
- Thread starter Lightning_Strikes_Twice
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
the difference is the insulation. as long as the stranding is the same, terminations won't matter. it is much harder to pull and thicker so fewer wires will go in the same size conduit.
I am not even sure it is a type of insulation allowed by the NEC.
In any case, it is a poor choice for building wire versus THHN or some variant of THHN.
masterinbama
Senior Member
- Location
- Huntsville Alabama
It's great for control panel wiring because it's very flexible. Not so great for pullin out in the field.
Fulthrotl
~Autocorrect is My Worst Enema.~
- Occupation
- E
MTW... machine tool wire..... oil and petrochemical resistant, at least more than most
insulations. mainly used for industrial control applications. lotsa #14's etc.
no nylon jacket to get snarfy.
makes beautiful control panels. everything else looks fugly alongside it.
pull 30 #14' mtw thru 100' of conduit with T's and elbows on a conveyor system,
without splices and.... it sucks, mostly. the texture of the insulation tends to slow
things down pretty badly.
i used to use it a lot more in years past than i do now, mostly 'cause i'm not
doing the control work i used to see a lot of.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Table 310.104(A) tells us what 600 volt or less insulation types are permitted by NEC - MTW is in there.
- Location
- Illinois
- Occupation
- retired electrician
It is my opinion that the "application provisions" of that table limit the use of MTW to wiring that is part of a machine tool, unless the conductor has additional markings on it.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
True, other conductors permitted by NEC may also have particular limitations. Some conductors do have multiple markings on them meaning they can be used for any of the ratings marked on them.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I thought alot of the dual rated thhn /thwn was also mtw rated. I have seen it on some larger wires at our supply company
- Location
- Illinois
- Occupation
- retired electrician
Yes that is true, but it does not behave like real MTW as far as how it looks when you wire a panel. Most of the MTW used for panel wiring is not dual rated and not suitable for NEC applications.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
- Status