Thermostat wire size requirement?

Reply

  #1  
Old 10-22-15, 08:33 PM
G
Member
Thread Starter
Join Date: Sep 2009
Location: USA
Posts: 149
Received 0 Votes on 0 Posts
Thermostat wire size requirement?

I want to replace my old 3-wire thermostat cable with a 7-wire cable. For now I'm just going to use 4 wires (adding the C) but I don't want to change the cable again in the future.

The ones I found at local hardware stores are 18/7. They are quite stiff to fish/pull through walls. What is the thinnest allowed by code and where can I buy them? I need less than 50 feet.

Location around Seattle WA.
 
  #2  
Old 10-22-15, 08:47 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 61,398
Received 1,399 Votes on 1,296 Posts
That's it. Thermostat wiring is #18 solid. Most home improvement stores carry it. Some have it on master rolls and will cut to length.

50 ft 18-AWG 7-Conductor Thermostat Wire at Your Lowes
 
  #3  
Old 10-22-15, 10:10 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
Maybe you can get lucky as I did. I don't remember if it was Lowes or Home Depot but I picked up a fifty foot spool of nine conductor and when I got to the checkout noticed it didn't have a price code sticker. The clerk called for a price check and after a couple of minutes with no response he said, "Free today" and put it in the bag.

Although I don't recommend it, I have seen four-pair telephone cable used for thermostats.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: