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#23289 - 03/14/03 02:49 PM # 18,16 THHN in conduits for class 1 wiring - art. 725  
Philip White  Offline
Joined: Aug 2002
Posts: 12
trenton, tennessee, usa
hi all,
i am looking at the design of class 1 wiring in a conduit using # 16,18 AWG thhn wire.
i am trying to find the number of # 16 & 18 awg wires that can be placed in various conduits. the smallest listing is for # 14. the nec 2002 code book does not list the cross sectional area for this wire in the tables. i had to go all the way back to nec-87 to find the cross sectional area.

does anyone know of a code issue that prevents me from using this wire for control wiring--- photo cells, switches, valves?

and where or how do you find the cross sectional wiring area?

thank you in advance.

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#23290 - 03/14/03 03:25 PM Re: # 18,16 THHN in conduits for class 1 wiring - art. 725  
JBD  Offline
Joined: Jul 2001
Posts: 599
Normally #16 and #18 wire is type TFFN or MTW not THHN.

The OD are:
16 - .10"
18 - .09"
MTW/AWM (quad-rated)
16 - .12"
18 - .11"

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