what do the wire types mean

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dispatcher7

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I am trying to find out what is different about the different types of wire. Example the difference between size 14 AWG Type TW and size 14 Type THHN. Where can I get this type of information?
 

iwire

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Massachusetts
Re: what do the wire types mean

Table 310.13 Conductor Application and Insulations

TW for example is Flame- retardant, moisture -resistant thermoplastic. For dry or wet locations, with a maximum operating temp of 60 C

THHN is Flame- retardant, heat-resistant thermoplastic for dry or damp locations with a maximum operating temp of 90 C
 

Nick

Senior Member
Re: what do the wire types mean

There is a pretty significant difference in size between TW and THHN as well. TW is pretty tough to pull and almost never seen anymore in new installations.
 

charlie b

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Lockport, IL
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Retired Electrical Engineer
Re: what do the wire types mean

The letters describe the type and rating of the insulation. The ?T? stands for ?thermoplastic.? It is good for a 60 degree C temperature rise, with an ambient temperature of 30C. The ?H? stands for ?add one measure of heat.? It means that you add 15 degrees C to the temperature rating. So a ?T? is good for 60C, a ?TH? is good for 75C, and a ?THH? is good for 90C. The ?W? stands for ?wet,? and tells you the conductor can withstand a wet environment.

The ?AWG? stands for ?American Wire Gauge.? The bigger the number, the smaller the wire. For example, most household circuits will use a #12. A #14 is smaller than this, and a #10 is bigger. The size of the wire is related to the amount of current it can safely carry. The larger the wire, the more current.
 

dereckbc

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Plano, TX
Re: what do the wire types mean

To add to what Charlie said, R is for thermoset rubber, and -2 is another heat measure. For example a cable listed RHW-2 is ruber insulated, 90 degree, wet or dry locations.

X is another designation for for cross-linked thermoset plastic for example XHHW-2 would be Cross-Linked synthetic polymer rated for 90 degrees is wet locations.

It is a little confusing at times. But genneraly the first letter or two designate the insulation type followed by heat a water designation, but not always. For example FEP and FEPB is Fluorinated Ethylene Propylene (Teflon) 90 and 200 degree respectively, dry and damp locations.
 

charlie b

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Location
Lockport, IL
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Retired Electrical Engineer
Re: what do the wire types mean

Oops! Yes, it is nylon. Should not have gone from memory, for tis the memory that is gone.
 
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