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tranai
Nov 8, 2008, 07:33 AM
How many wires #12 can I put in 1 1/4 EMT conduit? (inch'n a quarter)
Thank You!

stanfortyman
Nov 8, 2008, 08:41 AM
You can put 45- #12 THHN conductors in 1-1/4" EMT conduit.

Next question: WHY do you ask this??

The number of conductors is one thing. There are many other factors to consider.
What about derating for more than 3 current carrying conductors (CCCs)?

For #12, once you get over 9 CCCs in a conduit you need to derate to less than the typical 20A circuit.
With 10- #12 CCCs in a conduit you must derate to 50% of the actual amperage, which is then 15 amps (actual is 30A for #12 THHN).
Over 20 CCCs and you must derate to 45%.
Over 30 CCCs and you are limited to 40%.

Just knowing the maximum # is only getting part of the story.

tkrussell
Nov 9, 2008, 04:00 AM
And, keep in mind, Stan mentions only THHN insulation, because it is the typical wire used,and you did not specify an insulation type.

Wires with different insulation changes the maximum count allowed in a conduit.

Another popular insulation is XHHW, and only 33 #12 are allowed in 1.25" EMT, for example.

And, for the benefit of others, the wire count for any wire size is not typical for all types of conduits. Each type may have a different maximum wires allowed, due to different inside dimension. All of the various types of conduit and the respective maximum wires allowed are listed in Annex C tables of the NEC.

stanfortyman
Nov 9, 2008, 07:14 AM
All good points TK.

I hope tranai comes back to explain why he asked this. Unless it was another homework question. :mad: :rolleyes: