#18 THHN

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mstrlucky74

Senior Member
Location
NJ
If you need 18AWG you will likely need to go with type MTW.

The chart you mentioned has moved to 310.104 in 2011 NEC

They are asking for (2) #18 AWG wire from a set of contacts on a disconnect switch to a controller. There is no spec and thats all they say. I will assume a control cable(non plenum) in pipe and qualify.
 

kwired

Electron manager
Location
NE Nebraska
They are asking for (2) #18 AWG wire from a set of contacts on a disconnect switch to a controller. There is no spec and thats all they say. I will assume a control cable(non plenum) in pipe and qualify.

That may work, don't know enough about your installation. If a CL2 circuit then that is what would be used most cases - in a raceway is going to be a design spec and usually not an NEC requirement.
 

cmreschke

Senior Member
thhn is not made smaller than #14.

tffn is the closest under #14.

Incorrect. We install #16 thhn for control wiring all the time. Mostly for coil voltage for contactors for our defrost panels in grocery stores. It comes on 500' rolls just like the larger sized wire. It is a common item at our supply counter.
 

kwired

Electron manager
Location
NE Nebraska
Incorrect. We install #16 thhn for control wiring all the time. Mostly for coil voltage for contactors for our defrost panels in grocery stores. It comes on 500' rolls just like the larger sized wire. It is a common item at our supply counter.

Are you sure it is THHN? TFFN looks the same.
 

cmreschke

Senior Member
Never really looked hard. Will have to do so next time. Always ordered it as thhn and never been questioned on it
 
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