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| Subject - Will 150-AMP panel box enough? | |
| john2go |
I'm about two install 2 10-HP(3-phase) condensing units. Each unit runs at 70 amps. Will the 150-amp(3-phase, 208/230) panel box supply enough power? Should I use the #6 or #4 copper? Distance btwn the units and the subpanel is about 20 feet. Appreciate any help. John |
| wareagle | Unless you can be sure that these units will not run at the same time 150 amps service will not be large enough. I think these units will be considered continuous loads and requires that the load be caculated as follows: 70a + 70a = 140 amps x 1.25 = 175 amps. 200 amp service would be required. |
| sijagur | I agree with wareagle(is it your true name?). Considering with power loss in conductors, heat produced in panel, and other componets that should be feed from this panel, 200 A panel box is a right choice. |
| john2go | I will have to run new wires and expand the panel box. The reason I wanted to use this 150-AMP panel because it's an existing box that sits on the roof. Would you think that #6 copper is sufficient for 70-AMP? Only 20 feet way. john |
| wareagle | John Are you an electrician? If so I think you should be able to look in table 310.16 and determine that the ampacity of #6 is only good for 65 amps at 75C. So why don't you look at the table an try to come up with the correct size. Most people on this forum are willing to help but an effort on your part is desired. Bob |
| Ryan_J | Wareeagle is right. With motors you can take 125% of the largest motor's FLA + 100% of the others, but with A/C's ther is no such luxury. You must take 125% of all. |
| frenchelectrician | i really dont want to slam on your face here but for 10 Hp motor you say it draw 70Amps each ?? i came up 32 amp on my chart with me or you are refering it have two electric motors in there ?? i just want clear up this fact before it get out of hand and of course the 150 amp box will not cut it at all better off use 200 amp box or larger to handle the load you describing here Merci, Marc |
| wareagle | Marc You are correct about the FLA of the 10 HP. I did not look at the table. Where have you been? You haven't paid a visit in a while. |
| frenchelectrician | quote: that the reason why i asked here about the motor setup and i want to make sure it is clear there but run on 208 volt will take little more current than 240 volt verson there and if that unit do have name plate it can listed min or max current and some case fuse or breaker rating there for the wire size i will suggest to use min of #4 that is good for up to 80 amps if i recall it right but depending if you are using THHN or THWN or other types then you have to read the chart for correct wire size baised on 75° chart there Bob , sorry i was pretty busy but now just about caught up and try to get my self up the speed in the fourm :D |