How plenty of 12 ga circuits deserve to I install in 1/2" EMT?How many 12 ga circuits can I install in 3/4" EMT?Many thanks!Bill


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How numerous 12 ga circuits deserve to I download in 1/2" EMT?How numerous 12 ga circuits have the right to I install in 3/4" EMT?Many thanks!Bill
Bill,See this thread:http://forum.jajalger2018.org/showthread.php?t=81969 This thread additionally answers the question around the common neutrals. It"s a long thread, yet well precious it considering the inquiries you room asking. I understand *I* learned a lot native it.
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Early in the tread, it claims I can use 12 thhn conductors in 3/4"Is this correct?How about how many thhn conductors in 1/2"?Has thhn changed thw?Thanks.Bill
You deserve to install 16 THHN #12 awg in 3/4" EMT and also 9 THHN #12"s in 1/2" EMT regarding conduit to fill of 40%. You can not exceed this 40 % in EMT for over 2 wires. If you install 4 come 6 dimension 12 awg THHN existing carrying conductors in 1/2" EMT then you need to derate come 80% making use of the 90 C pillar of table 310.16. For this reason the 30 amp #12 is now 24 amp rated. 7 to 9 #12 THHN conductors you have to derate 70% so friend are now rated in ~ 21 amps for the size and also insulation rated conductor. You cant install more than 9 THHN #12 awg current carrying conductors in 1/2" EMT so you space finished at this point. THHN/THWN is the an ext common insulation supplied today vs the THW
Roger i think you have actually it just partially correct. The beginning point for deration is not 20 amps because that this application. You have the right to use approximately 9 prior to you are listed below the 20 amp threshold.
My question had actually three parts:1.How countless 12 ga conductors have the right to be provided in 1/2" EMT with a 20 amp breaker?2. " " " 3/4" EMT?3. Does thhn have a far better rating enabling for more conductors?ThanksBill


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Joed: yes deration for this application would certainly be calculated native the 90 degree column therefore would begin at 30 amps not 20 amps my mistake. I have actually edited the post. Friend must additionally consider ambient temp factors of 310.16 prior to derating for number of wires in conduit. 1.) 9 THHN #12 awg existing carrying conductors before you drop listed below 20 amp rating. 2.) quiet is 9 THHN"s before downsizing the breaker come 15 amps you deserve to fill the conduit come 40% the its cross sectional area if over 2 wires therefore you can put a preferably of 16 THHN #12"s in 3/4 EMT. 40% equals .213sq.in. Because that 3/4 EMT. One #12 THHN is .0133sq.in. So 16 x .0133sq.in. Is .2128sq.in. Quite much specifically .213 or 40% of the cross sectional area the 3/4 EMT. If you put over nine wires as much as 16 wires climate the ampacity derates from a starting point of 30 amps come 15 amps. 3.) THHN is rated at 90 C (194 F) however I am using it here for deration purposes. Plenty of factors get in into the really temp. Pillar from table 310.16 for which ampacity is calculated. Depends on the temp. Rating the the machine you room connecting to, even if it is its a motor, that sort of information.THW is rated a 75C as opposed to THHN at 90C therefore the beginning point because that #12 THW would certainly be 25 AMPS because that deration objectives for conduit after ~ considering the ambient temp factors. The overcome sectional area is additionally greater for THW 보다 THHN (.0260sq.in vs .0133sq.in.) therefore the number of wires in the conduit will be much less for THW vs THHN regarding the end 2 wires 40% fill restriction.Example: You have actually a #8 THW conductor in a conduit together with 5 others because that a total of 6 current carrying conductors. The ambient temp for the environment is 50 C. In the 75 C columnn the 310.16. The correction aspect for this ambient is .75. The ampacity for 75 C #8 THW is 50 amps. For this reason .75 time 50 is 37.5 amps. Currently you must take into consideration the deration early out to variety of wires in a conduit. In this case the deration percent would certainly be 80% because that 6 wires in a conduit. So 37.5 time .80 is 30 amps. Then think about 110.14 if your conductor is much less than 1 awg and compare your final ampacity come the 60 level column of 310.16 and chose the smaller sized of the two because of termination restrictions. In this instance 30 amps is the last ampacity rating for an #8 awg THW conductor in conduit with five other conductors.Having funny yet?