MTW TEW Wire

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Joe Cool

Member
Hello and good day.

I've got a 250 ft. spool of #10 AWG MTW/TEW 105 degree C, stranded wire
came from a garage sale. The wire is in good shape.
Can I use it in my house if I run it in EMT, to hook up my water heater?

Thanks for your time.
 

tkb

Senior Member
Location
MA
I don't think so.
MTW is only for machine tool wiring and TEW is not listed in the NEC as building wire.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
I don't think so.
MTW is only for machine tool wiring and TEW is not listed in the NEC as building wire.
Bingo. Such is the danger of providing advice to the DIY crowd, they don't know that not all advice is correct advice. The "ayes" may have had it, but they were all wrong up to that point.

Neither version is suitable for pulling in conduit, it lacks the abbrasion resistance and pull strength necessary, because it sacrified that in order to be extra flexible. TEW (Thermoplastic Equipment Wire) and MTW (Machine Tool Wire, its un-tinned cousin) are intended to be used in control cabinets and appliances only, so they dont need what it takes to be pulled in conduit, hence why you dont see them in the NEC, which is about intallations, not manufacturing of products. They also, I believe, do not have to meet the same flame propagation tests that building wire does, meaning if a fire starts in one cabinet, the wire insulation will snuff itself out before it lets it get to the next one. If the wire is only allowed to be used inside of one cabinet or appliance, that is unnecessary, but is another reason it is not suitable for field installation, even in conduit.
 
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