MTW wire

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bwyllie

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Can type MMW wire be used as branch circuit/feeder wiring?
 
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310.13 Conductor Constructions and Applications. Insulated
conductors shall comply with the applicable provisions
of Table 310.13(A) through Table 310.13(E). These conductors shall be permitted for use in any of the wiring methods recognized in Chapter 3 and as speci-fied in their respective tables or as permitted elsewhere in
this Code.

The applicable provision of MTW state that it is specifically designed for machine wiring but it doesn't disallow it in other use like some other wires.
IMO 310.13 allows any of the conductors to be used "in any of the wiring methods recognized in Chapter 3".

Unless is specifically says ONLY in the applicable provisions your are good to go.

Just My opinion
 
Machine Tool Wire: Understanding MTW and UL1015

Machine Tool Wire, or most commonly referred to as MTW, is a stranded flexible hook up wire. MTW is used for the internal wiring of appliances including refrigeration equipment, automatic washers, air-conditioning equipment, control wiring for machine tools and in various other building applications.


I am aware of two different types of MTW.

1. MTW designated simply as MTW. It is the wire described above. It has been designed for the wiring of appliances and such. There are more strands and it is very flexible.

2. MTW designated as THHN/MTW. This conductor is different than above, as it has the typical stranding we see in THHN. You can find the number of strands per conductor in Table 8, Chapter 9.


Number 1 is not permitted for building wiring and number 2 is.


You can find more info about this topic in Google.
 
Pierre C Belarge said:
Machine Tool Wire: Understanding MTW and UL1015

Machine Tool Wire, or most commonly referred to as MTW, is a stranded flexible hook up wire. MTW is used for the internal wiring of appliances including refrigeration equipment, automatic washers, air-conditioning equipment, control wiring for machine tools and in various other building applications.


I am aware of two different types of MTW.

1. MTW designated simply as MTW. It is the wire described above. It has been designed for the wiring of appliances and such. There are more strands and it is very flexible.

2. MTW designated as THHN/MTW. This conductor is different than above, as it has the typical stranding we see in THHN. You can find the number of strands per conductor in Table 8, Chapter 9.


Number 1 is not permitted for building wiring and number 2 is.


You can find more info about this topic in Google.
Click to expand...

What is the code reason behind it not being allowed for building wiring.
 
Twoskinsoneman said:
What is the code reason behind it not being allowed for building wiring.
Click to expand...

I think 310.13 says "Insulated conductors shall comply with the applicable provisions of Table 310.13(A) through Table 310.13(E)".

Tha applicable provisions of table 310.13(A) for MTW allow it to be used for "Machine Tool Wiring". That is all that is allowed. If the particular wire has multiple ratings, such as THHN or THWN-2, then we are subject to those restrictions or permissions, when used in that manner.

If that conductor happens to say 105 deg C for "Appliance Wiring Use", that does not allow us to use it at that temperature as THHN for branch circuit use.

I beleive that the provisions of the tables in 310.13 are exclusive.
 
If a cable is rated MTW/THW 105 degree cable is this an approved conductor application and insulation. Table 310.13 lists MTW as machine tool wiring and Table 310.13 only lists type THW at 75 and 95 degrees?
 
Volta said:
I think 310.13 says "Insulated conductors shall comply with the applicable provisions of Table 310.13(A) through Table 310.13(E)".

Tha applicable provisions of table 310.13(A) for MTW allow it to be used for "Machine Tool Wiring". That is all that is allowed. If the particular wire has multiple ratings, such as THHN or THWN-2, then we are subject to those restrictions or permissions, when used in that manner.

If that conductor happens to say 105 deg C for "Appliance Wiring Use", that does not allow us to use it at that temperature as THHN for branch circuit use.

I beleive that the provisions of the tables in 310.13 are exclusive.
Click to expand...

It also says "These conductors shall be permitted for use in any of the wiring methods recognized in Chapter 3 and as speci-fied in their respective tables or as permitted elsewhere in
this Code."

There's nothing that implies the provisions are exclusive. But there is evidence to support that it is not exclusive such as "Switchboard wiring only". Why do they specify "only" on some wires but absent mindedly forget it on others?

310.8 (A)-(D) tells you what wires are acceptable to the code. Unless the code forbids it's use in certain places through out the rest of the code than I believe it is fine.
 
The NEC doesn't really apply inside a machine so why would they bother to say anything about MTW wiring if it was only usable inside a machine of some sort?
 
petersonra said:
The NEC doesn't really apply inside a machine so why would they bother to say anything about MTW wiring if it was only usable inside a machine of some sort?
Click to expand...


Exactly. If you read the code article where does it prohibit it?
It calls out MTW in 310.8 as being ok. Unless it specifically prohibits its use somewhere else I would not red tag it.
 
I'm not going to try to argue the point of 'MTW is not explicitly permitted for building wire' versus 'MTW is not prohibited for building wire'. I can see both sides of this one.

However many of the device terminations that this wire would need to be connected to are almost certainly not listed for use with fine stranded wire. If for some reason I wanted to use MTW, I'd be careful to investigate everything that it was being connected to.

-Jon
 
winnie said:
I'm not going to try to argue the point of 'MTW is not explicitly permitted for building wire' versus 'MTW is not prohibited for building wire'. I can see both sides of this one.

However many of the device terminations that this wire would need to be connected to are almost certainly not listed for use with fine stranded wire. If for some reason I wanted to use MTW, I'd be careful to investigate everything that it was being connected to.

-Jon
Click to expand...


This is great point Winnie. I certainly don't want to downplay that fact that there may be difficulty using a fine stranded wire (as far as finding applicable terminations for it) I just don't like that blanket statement "it is not allowed because we use THHN and that's that"
 
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