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When buying extension cords and other types of wiring,I consistently see fractions. I see that it may be a reference to the conduction capabilities of the wire? Please explain. For example:

"Southwire 18/5 thermostat wire"

https://www.amazon.com/Southwire-64169622-Conductor-Thermostat-Power-Limited/dp/B0069F4HHC

Jimmy Joslington
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adivis12
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It is not a fraction. 18/5 means that there are five (5) conductors and each is 18 AWG (american wire gauge). The gauge relates to the current carrying capacity of each conductor.

It was all specified in the title of the amazon link that you provided:

Southwire 64169622 5 Conductor 18/5 Thermostat Wire, 18-Gauge Solid Copper Class 2 Power-Limited Circuit Cable, 50-Feet, Brown

Michael Karas
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  • Ok, so basically, it just means there are 5 wires inside. So in an extension cord, it would be x number of wires that are each y gauge. Thanks! – adivis12 Nov 28 '17 at 16:43
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    The other time you see fractions is on very heavy gauge wire, but it's only with zero on the bottom like 1/0, 2/0, and is normally pronounced one-ought, two-ought, etc. You don't typically use this wire unless you're installing a main panel. – JPhi1618 Nov 28 '17 at 17:24
  • Just to confuse things, this "code" may be written either way up: 5/18 or 18/5 both mean 5 conductors, #18. We can usually tell from context (and common sense) which number is the number of conductors, and which is the conductor size (You'll never see a cable with 18 #5 conductors) – Peter Bennett Nov 28 '17 at 20:51
  • To clear up (or add?) more possible confusion -- 14/2 romex has two conductors and a ground wire. – rrauenza Nov 28 '17 at 23:15