How plenty of 12 ga circuits have the right to I install in 1/2" EMT?How numerous 12 ga circuits can I install in 3/4" EMT?Many thanks!Bill


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How countless 12 ga circuits have the right to I download in 1/2" EMT?How numerous 12 ga circuits can I install in 3/4" EMT?Many thanks!Bill
Bill,See this thread:http://forum.rebab.net/showthread.php?t=81969 This thread also answers the question around the usual neutrals. It"s a lengthy thread, however well worth it considering the inquiries you room asking. I recognize *I* learned a lot from it.
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Early in the tread, it says I might use 12 thhn conductors in 3/4"Is this correct?How around 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 fill of 40%. You cannot exceed this 40 % in EMT because that over 2 wires. If you install 4 come 6 dimension 12 awg THHN existing carrying conductors in 1/2" EMT then you must derate come 80% making use of the 90 C column of table 310.16. So the 30 amp #12 is now 24 amp rated. 7 to 9 #12 THHN conductors you should derate 70% so you are now rated in ~ 21 amps for that size and also insulation rated conductor. You cant install more than 9 THHN #12 awg current carrying conductors in 1/2" EMT therefore you are finished in ~ this point. THHN/THWN is the more common insulation offered today vs the THW
Roger ns think you have actually it only partially correct. The starting point for deration is not 20 amps because that this application. You have the right to use up to 9 before you are below the 20 amp threshold.
My question had actually three parts:1.How countless 12 ga conductors deserve to be used in 1/2" EMT v a 20 amp breaker?2. " " " 3/4" EMT?3. Walk thhn have a better rating enabling for an ext conductors?ThanksBill


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Joed: correct deration for this application would be calculated indigenous the 90 level column for this reason would begin at 30 amps not 20 amps mine mistake. I have actually edited that post. Girlfriend must additionally consider ambient temp determinants of 310.16 before derating for variety 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 prior to downsizing the breaker to 15 amps you can fill the conduit come 40% of its cross sectional area if over 2 wires therefore you can put a preferably of 16 THHN #12"s in 3/4 EMT. 40% equates to .213sq.in. Because that 3/4 EMT. One #12 THHN is .0133sq.in. For this reason 16 x .0133sq.in. Is .2128sq.in. Quite much specifically .213 or 40% that the cross sectional area the 3/4 EMT. If you placed over ripe wires as much as 16 wires then the ampacity derates native a beginning point that 30 amps come 15 amps. 3.) THHN is rated in ~ 90 C (194 F) but I am making use of it here for deration purposes. Plenty of factors go into into the actual temp. Column 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 together opposed come THHN at 90C therefore the beginning point for #12 THW would be 25 AMPS for deration purposes for conduit ~ considering the ambient temp factors. The cross sectional area is likewise greater because that THW 보다 THHN (.0260sq.in vs .0133sq.in.) therefore the variety of wires in the conduit will be less for THW vs THHN as to the end 2 wires 40% fill restriction.Example: You have a #8 THW conductor in a conduit in addition to 5 others because that a total of 6 current carrying conductors. The approximately temp for the surroundings is 50 C. In the 75 C columnn the 310.16. The correction aspect for this approximately is .75. The ampacity for 75 C #8 THW is 50 amps. Therefore .75 times 50 is 37.5 amps. Currently you must take into consideration the deration early to number of wires in a conduit. In this instance the deration percent would be 80% for 6 wires in a conduit. So 37.5 time .80 is 30 amps. Then consider 110.14 if your conductor is less than 1 awg and also compare your last ampacity to the 60 level column the 310.16 and also chose the smaller sized of the two because of termination restrictions. In this situation 30 amps is the final ampacity rating for an #8 awg THW conductor in conduit with five other conductors.Having fun yet?