Romex Wire Gauge Ampacity

The official home of romex.

Romex wire gauge ampacity. This little tip can help you choose the correct sized wire. Using romex 6 3 as a example. Conductor ampacity amperage capacity romex contains 90 c conductors article 334 80 limits its ampacity to the 60 c level. Use the stayonline wire ampacity chart to look up the rated amperage of different sizes and types of cords.

Wire gauge size 60 c 140 f nm b uf b 75 c 167 f thw thwn se use xhhw 90 c 194 f thwn 2 thhn xhhw 2 use 2 75 c 167 f thw thwn se use xhhw 90 c 194 f xhhw 2 thhn thwn 2 14 15. Among residential electricians even good one s i find that using 8 romex for 50 amps is a very common violation. Also if each conductor is carrying 120 volts is the whole. The allowable ampacity of each conductor shall be reduced as shown in the following table.

As speedy points out romex has that code limitation to the 60 degree column on the ampacity chart. This amp chart highlights the types of cords gauge size range number of cord coductors ampacity of current carrying. Wire size amps wire type 3 0 gauge 200 amps service entrance 1 0 guage 150 amps service entrance and feeder wire 3 guage 100 amps service entrance and feeder wire 6 guage 55 amps feeder and large appliance wire. Electrical current is measured as ampacity.

Number of percent of values in current carrying table as adjusted for conductors ambient temp if necessary 4 thru 6 7 thru 9 10thru20. I guess it kinda messes with your head if you normally work with mc pipe and wire as well as romex in your day to day job. Southwire romex brand simpull nm b nonmetallic sheathed cable may be used for both exposed and concealed work in normally dry locations at temperatures not to exceed 90 c with ampacity limited to that for 60 c conductors as specified in the 2011 national electrical code. Wire gauge size copper aluminum 60 c 140 f 75 c 167 f 90 c 194 f 75 c 167 f 90 c 194 f nm b thw thwn 2 thw xhhw 2 uf b thwn thhn thwn thhn se xhhw 2 se twhn 2 use use 14 15 15.

If this cable has 2 conductors and a neutral will the l1 and l2 conductor carry 55 amps or is 55 amps the total of both l1 and l2 combined.