# electrical question

if my generator can output 30 amps 240, i can take the 240 and split it to 120 and output a total of 60 amps, 30 each leg, now how much current is
flowing on the neutral? i have a 10/3 stranded cable about 90 feet long, i dont know if it will be 60 or 30. my service entrance cable all three look the same size wire so i guessing it will be 30. thanks tony
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The current on the neutral would be the difference between current on one leg and current on another leg, if they share a neutral. Never more than current on one of the legs.

I am attaching a AWG table. I would suggest brushing up on electricity a little bit before starting any ambitious projects. You may save a life.
====================================================================AWG Wire Table for BARE COPPER Wire Compiled by a program written by Fr. Tom McGahee
Compiled by Fr. Tom McGahee tom snipped-for-privacy@sigmais.com Permission granted to copy freely so long as credit line above is included
AWG = American Wire Gauge size Dia-mils = Diameter in mils (1 mil = .001 inch) TPI = Turns Per Inch (Ignoring thickness of unknown insulation) Dia-mm = Diameter in millimeters (For comparison with non-USA coilers) Circ-mils = Circular Mils. (circular mils = diameter in mils squared) Ohms/Kft = Ohms Per 1,000 Feet Ft/Ohm = Feet Per Ohm Ft/Lb = Feet Per Pound Ohms/Lb = Ohms Per Pound Lb/Kft = Pounds Per 1,000 Feet NormAmps = Normal Average Amp Capacity based on 500 circular mils per Amp MaxAmps = Maximum recommended Average Amp Capacity in Open Air based on 438.489 circular mils per Amp
Actual Amp capacity of a wire depends on form factor and method of cooling! MaxAmps assumes free flow of air around wire. Do NOT exceed this maximum without cooling! Wire wrapped in a coil or without any form of cooling may over-heat at MaxAmps! Many factors govern the ACTUAL Max Amps you can pass through a wire continuously. Be careful!
AWG Dia-mils TPI Dia-mm Circ-mils Ohms/Kft Ft/Ohm Ft/Lb Ohms/Lb Lb/Kft NormAmps MaxAmps
0000 459.99 2.1740 11.684 211592 0.0490 20402 1.5613 0.0001 640.48 423.18 482.55 000 409.63 2.4412 10.405 167800 0.0618 16180 1.9688 0.0001 507.93 335.60 382.68 00 364.79 2.7413 9.2657 133072 0.0779 12831 2.4826 0.0002 402.80 266.14 303.48
AWG Dia-mils TPI Dia-mm Circ-mils Ohms/Kft Ft/Ohm Ft/Lb Ohms/Lb Lb/Kft NormAmps MaxAmps
0 324.85 3.0783 8.2513 105531 0.0983 10175 3.1305 0.0003 319.44 211.06 240.67 1 289.29 3.4567 7.3480 83690 0.1239 8069.5 3.9475 0.0005 253.33 167.38 190.86 2 257.62 3.8817 6.5436 66369 0.1563 6399.4 4.9777 0.0008 200.90 132.74 151.36 3 229.42 4.3588 5.8272 52633 0.1970 5075.0 6.2767 0.0012 159.32 105.27 120.03 4 204.30 4.8947 5.1893 41740 0.2485 4024.7 7.9148 0.0020 126.35 83.480 95.190 5 181.94 5.4964 4.6212 33101 0.3133 3191.7 9.9804 0.0031 100.20 66.203 75.489 6 162.02 6.1721 4.1153 26251 0.3951 2531.1 12.585 0.0050 79.460 52.501 59.866 7 144.28 6.9308 3.6648 20818 0.4982 2007.3 15.869 0.0079 63.014 41.635 47.476 8 128.49 7.7828 3.2636 16509 0.6282 1591.8 20.011 0.0126 49.973 33.018 37.650 9 114.42 8.7396 2.9063 13092 0.7921 1262.4 25.233 0.0200 39.630 26.185 29.858
AWG Dia-mils TPI Dia-mm Circ-mils Ohms/Kft Ft/Ohm Ft/Lb Ohms/Lb Lb/Kft NormAmps MaxAmps
10 101.90 9.8140 2.5881 10383 0.9989 1001.1 31.819 0.0318 31.428 20.765 23.678 11 90.741 11.020 2.3048 8233.9 1.2596 793.93 40.122 0.0505 24.924 16.468 18.778 12 80.807 12.375 2.0525 6529.8 1.5883 629.61 50.593 0.0804 19.765 13.060 14.892 13 71.961 13.896 1.8278 5178.3 2.0028 499.31 63.797 0.1278 15.675 10.357 11.810 14 64.083 15.605 1.6277 4106.6 2.5255 395.97 80.447 0.2031 12.431 8.2132 9.3654 15 57.067 17.523 1.4495 3256.7 3.1845 314.02 101.44 0.3230 9.8579 6.5134 7.4271 16 50.820 19.677 1.2908 2582.7 4.0156 249.03 127.91 0.5136 7.8177 5.1654 5.8900 17 45.257 22.096 1.1495 2048.2 5.0636 197.49 161.30 0.8167 6.1997 4.0963 4.6709 18 40.302 24.813 1.0237 1624.3 6.3851 156.62 203.39 1.2986 4.9166 3.2485 3.7042 19 35.890 27.863 0.9116 1288.1 8.0514 124.20 256.47 2.0648 3.8991 2.5762 2.9376
AWG Dia-mils TPI Dia-mm Circ-mils Ohms/Kft Ft/Ohm Ft/Lb Ohms/Lb Lb/Kft NormAmps MaxAmps
20 31.961 31.288 0.8118 1021.5 10.153 98.496 323.41 3.2832 3.0921 2.0430 2.3296 21 28.462 35.134 0.7229 810.10 12.802 78.111 407.81 5.2205 2.4521 1.6202 1.8475 22 25.346 39.453 0.6438 642.44 16.143 61.945 514.23 8.3009 1.9446 1.2849 1.4651 23 22.572 44.304 0.5733 509.48 20.356 49.125 648.44 13.199 1.5422 1.0190 1.1619 24 20.101 49.750 0.5106 404.03 25.669 38.958 817.66 20.987 1.2230 0.8081 0.9214 25 17.900 55.866 0.4547 320.41 32.368 30.895 1031.1 33.371 0.9699 0.6408 0.7307 26 15.940 62.733 0.4049 254.10 40.815 24.501 1300.1 53.061 0.7692 0.5082 0.5795 27 14.195 70.445 0.3606 201.51 51.467 19.430 1639.4 84.371 0.6100 0.4030 0.4596 28 12.641 79.105 0.3211 159.80 64.898 15.409 2067.3 134.15 0.4837 0.3196 0.3644 29 11.257 88.830 0.2859 126.73 81.835 12.220 2606.8 213.31 0.3836 0.2535 0.2890
AWG Dia-mils TPI Dia-mm Circ-mils Ohms/Kft Ft/Ohm Ft/Lb Ohms/Lb Lb/Kft NormAmps MaxAmps
30 10.025 99.750 0.2546 100.50 103.19 9.6906 3287.1 339.18 0.3042 0.2010 0.2292 31 8.9276 112.01 0.2268 79.702 130.12 7.6850 4145.0 539.32 0.2413 0.1594 0.1818 32 7.9503 125.78 0.2019 63.207 164.08 6.0945 5226.7 857.55 0.1913 0.1264 0.1441 33 7.0799 141.24 0.1798 50.125 206.90 4.8332 6590.8 1363.6 0.1517 0.1003 0.1143 34 6.3048 158.61 0.1601 39.751 260.90 3.8329 8310.8 2168.1 0.1203 0.0795 0.0907 35 5.6146 178.11 0.1426 31.524 328.99 3.0396 10480 3447.5 0.0954 0.0630 0.0719 36 5.0000 200.00 0.1270 25.000 414.85 2.4105 13215 5481.7 0.0757 0.0500 0.0570 37 4.4526 224.59 0.1131 19.826 523.11 1.9116 16663 8716.2 0.0600 0.0397 0.0452 38 3.9652 252.20 0.1007 15.723 659.63 1.5160 21012 13859 0.0476 0.0314 0.0359 39 3.5311 283.20 0.0897 12.469 831.78 1.2022 26496 22037 0.0377 0.0249 0.0284
AWG Dia-mils TPI Dia-mm Circ-mils Ohms/Kft Ft/Ohm Ft/Lb Ohms/Lb Lb/Kft NormAmps MaxAmps
40 3.1445 318.01 0.0799 9.8880 1048.9 0.9534 33410 35040 0.0299 0.0198 0.0226
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thanks for the info, we just went from a 3500 generator, that ran constant for 1 week then 1.5 weeks,because of 2 hurricanes, i knew that 10 gauge stranded could handle the amps of the 3500 but the new 7550 puts out 62 amps so i wanted verification that the neutral would not be overloaded. thanks tony

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is that 62 amps as sum of 2 legs?
By the way, I also have a 7 kW generator:
http://igor.chudov.com/tmp/onan/Diesel/
i

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yes the sum is 62...thanks tony

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You don't necessarily rate the wire size by what current the generator can source, but how much power the loads draw. Usually we treat them one and the same, but it's an important distinction. If you don't change your loads, but upgrade your generator, then upgrading the wiring isn't a necessity.
| > Permission granted to copy freely so long as credit line above is included | > | > AWG = American Wire Gauge size | > Dia-mils = Diameter in mils (1 mil = .001 inch) | > TPI = Turns Per Inch (Ignoring thickness of unknown insulation) | > Dia-mm = Diameter in millimeters (For comparison with non-USA coilers) | > Circ-mils = Circular Mils. (circular mils = diameter in mils squared) | > Ohms/Kft = Ohms Per 1,000 Feet | > Ft/Ohm = Feet Per Ohm | > Ft/Lb = Feet Per Pound | > Ohms/Lb = Ohms Per Pound | > Lb/Kft = Pounds Per 1,000 Feet | > NormAmps = Normal Average Amp Capacity based on 500 circular mils per Amp | > MaxAmps = Maximum recommended Average Amp Capacity in Open Air based on | > 438.489 circular mils per Amp | > | > Actual Amp capacity of a wire depends on form factor and method of | > cooling! | > MaxAmps assumes free flow of air around wire. Do NOT exceed this maximum | > without cooling! | > Wire wrapped in a coil or without any form of cooling may over-heat at | > MaxAmps! | > Many factors govern the ACTUAL Max Amps you can pass through a wire | > continuously. Be careful! | > | > | > | > AWG Dia-mils TPI Dia-mm Circ-mils Ohms/Kft Ft/Ohm | > Ft/Lb Ohms/Lb Lb/Kft NormAmps MaxAmps | > | > 0000 459.99 2.1740 11.684 211592 0.0490 20402 | > 1.5613 0.0001 640.48 423.18 482.55 | > 000 409.63 2.4412 10.405 167800 0.0618 16180 | > 1.9688 0.0001 507.93 335.60 382.68 | > 00 364.79 2.7413 9.2657 133072 0.0779 12831 | > 2.4826 0.0002 402.80 266.14 303.48 | > | > AWG Dia-mils TPI Dia-mm Circ-mils Ohms/Kft Ft/Ohm | > Ft/Lb Ohms/Lb Lb/Kft NormAmps MaxAmps | > | > 0 324.85 3.0783 8.2513 105531 0.0983 10175 | > 3.1305 0.0003 319.44 211.06 240.67 | > 1 289.29 3.4567 7.3480 83690 0.1239 8069.5 | > 3.9475 0.0005 253.33 167.38 190.86 | > 2 257.62 3.8817 6.5436 66369 0.1563 6399.4 | > 4.9777 0.0008 200.90 132.74 151.36 | > 3 229.42 4.3588 5.8272 52633 0.1970 5075.0 | > 6.2767 0.0012 159.32 105.27 120.03 | > 4 204.30 4.8947 5.1893 41740 0.2485 4024.7 | > 7.9148 0.0020 126.35 83.480 95.190 | > 5 181.94 5.4964 4.6212 33101 0.3133 3191.7 | > 9.9804 0.0031 100.20 66.203 75.489 | > 6 162.02 6.1721 4.1153 26251 0.3951 2531.1 | > 12.585 0.0050 79.460 52.501 59.866 | > 7 144.28 6.9308 3.6648 20818 0.4982 2007.3 | > 15.869 0.0079 63.014 41.635 47.476 | > 8 128.49 7.7828 3.2636 16509 0.6282 1591.8 | > 20.011 0.0126 49.973 33.018 37.650 | > 9 114.42 8.7396 2.9063 13092 0.7921 1262.4 | > 25.233 0.0200 39.630 26.185 29.858 | > | > AWG Dia-mils TPI Dia-mm Circ-mils Ohms/Kft Ft/Ohm | > Ft/Lb Ohms/Lb Lb/Kft NormAmps MaxAmps | > | > 10 101.90 9.8140 2.5881 10383 0.9989 1001.1 | > 31.819 0.0318 31.428 20.765 23.678 | > 11 90.741 11.020 2.3048 8233.9 1.2596 793.93 | > 40.122 0.0505 24.924 16.468 18.778 | > 12 80.807 12.375 2.0525 6529.8 1.5883 629.61 | > 50.593 0.0804 19.765 13.060 14.892 | > 13 71.961 13.896 1.8278 5178.3 2.0028 499.31 | > 63.797 0.1278 15.675 10.357 11.810 | > 14 64.083 15.605 1.6277 4106.6 2.5255 395.97 | > 80.447 0.2031 12.431 8.2132 9.3654 | > 15 57.067 17.523 1.4495 3256.7 3.1845 314.02 | > 101.44 0.3230 9.8579 6.5134 7.4271 | > 16 50.820 19.677 1.2908 2582.7 4.0156 249.03 | > 127.91 0.5136 7.8177 5.1654 5.8900 | > 17 45.257 22.096 1.1495 2048.2 5.0636 197.49 | > 161.30 0.8167 6.1997 4.0963 4.6709 | > 18 40.302 24.813 1.0237 1624.3 6.3851 156.62 | > 203.39 1.2986 4.9166 3.2485 3.7042 | > 19 35.890 27.863 0.9116 1288.1 8.0514 124.20 | > 256.47 2.0648 3.8991 2.5762 2.9376 | > | > AWG Dia-mils TPI Dia-mm Circ-mils Ohms/Kft Ft/Ohm | > Ft/Lb Ohms/Lb Lb/Kft NormAmps MaxAmps | > | > 20 31.961 31.288 0.8118 1021.5 10.153 98.496 | > 323.41 3.2832 3.0921 2.0430 2.3296 | > 21 28.462 35.134 0.7229 810.10 12.802 78.111 | > 407.81 5.2205 2.4521 1.6202 1.8475 | > 22 25.346 39.453 0.6438 642.44 16.143 61.945 | > 514.23 8.3009 1.9446 1.2849 1.4651 | > 23 22.572 44.304 0.5733 509.48 20.356 49.125 | > 648.44 13.199 1.5422 1.0190 1.1619 | > 24 20.101 49.750 0.5106 404.03 25.669 38.958 | > 817.66 20.987 1.2230 0.8081 0.9214 | > 25 17.900 55.866 0.4547 320.41 32.368 30.895 | > 1031.1 33.371 0.9699 0.6408 0.7307 | > 26 15.940 62.733 0.4049 254.10 40.815 24.501 | > 1300.1 53.061 0.7692 0.5082 0.5795 | > 27 14.195 70.445 0.3606 201.51 51.467 19.430 | > 1639.4 84.371 0.6100 0.4030 0.4596 | > 28 12.641 79.105 0.3211 159.80 64.898 15.409 | > 2067.3 134.15 0.4837 0.3196 0.3644 | > 29 11.257 88.830 0.2859 126.73 81.835 12.220 | > 2606.8 213.31 0.3836 0.2535 0.2890 | > | > AWG Dia-mils TPI Dia-mm Circ-mils Ohms/Kft Ft/Ohm | > Ft/Lb Ohms/Lb Lb/Kft NormAmps MaxAmps | > | > 30 10.025 99.750 0.2546 100.50 103.19 9.6906 | > 3287.1 339.18 0.3042 0.2010 0.2292 | > 31 8.9276 112.01 0.2268 79.702 130.12 7.6850 | > 4145.0 539.32 0.2413 0.1594 0.1818 | > 32 7.9503 125.78 0.2019 63.207 164.08 6.0945 | > 5226.7 857.55 0.1913 0.1264 0.1441 | > 33 7.0799 141.24 0.1798 50.125 206.90 4.8332 | > 6590.8 1363.6 0.1517 0.1003 0.1143 | > 34 6.3048 158.61 0.1601 39.751 260.90 3.8329 | > 8310.8 2168.1 0.1203 0.0795 0.0907 | > 35 5.6146 178.11 0.1426 31.524 328.99 3.0396 | > 10480 3447.5 0.0954 0.0630 0.0719 | > 36 5.0000 200.00 0.1270 25.000 414.85 2.4105 | > 13215 5481.7 0.0757 0.0500 0.0570 | > 37 4.4526 224.59 0.1131 19.826 523.11 1.9116 | > 16663 8716.2 0.0600 0.0397 0.0452 | > 38 3.9652 252.20 0.1007 15.723 659.63 1.5160 | > 21012 13859 0.0476 0.0314 0.0359 | > 39 3.5311 283.20 0.0897 12.469 831.78 1.2022 | > 26496 22037 0.0377 0.0249 0.0284 | > | > AWG Dia-mils TPI Dia-mm Circ-mils Ohms/Kft Ft/Ohm | > Ft/Lb Ohms/Lb Lb/Kft NormAmps MaxAmps | > | > 40 3.1445 318.01 0.0799 9.8880 1048.9 0.9534 | > 33410 35040 0.0299 0.0198 0.0226 | > | > | > | > | > | > Prev: DIY Ball Lightning | > Next: Medhurts K formula [Qbasic listing] | > Index(es): | > | > Main | > Thread | |
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Ignoramus16317 wrote:

I'm not sure what sort of application this table deals with ampacity wise, but it certainly aint normal wiring methods, or else I'm reading it wrong. 12awg at 14.something amps? Better to consult your NEC tables. The other data is interesting but in light of the 'max amps' data might be questionable also.
Paul
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Tony
I know this isnt a TRICK question. But, with both 110 lines loaded the same, and resistive, there will be no current in the neutral, even though power is being delivered to the two loads.
Jerry
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| > if my generator can output 30 amps 240, i can take the 240 and split it to | > 120 and output a total of 60 amps, 30 each leg, now how much current is | > flowing on the neutral? i have a 10/3 stranded cable about 90 feet long, | > i dont know if it will be 60 or 30. my service entrance cable all three | > look the same size wire so i guessing it will be 30. thanks tony | > | Tony | | I know this isnt a TRICK question. But, with both 110 lines loaded the | same, and resistive, there will be no current in the neutral, even though | power is being delivered to the two loads. | | Jerry
Alright, I had to think about this one, and for the sake of the unknowing, it should be explained. If a 220V load is being used, then current flows from leg to leg, not leg to neutral, so the neutral carries no current, as noted by older 220V circuits not using the neutral or ground, just the two legs. If both legs are running 110V loads, however, then when one leg is at maximum positive voltage, current will also be at a maximum through that leg. However, the other leg will also be at maximum negative voltage, so current will also be at a maximum on that leg too. If the loads are equally balanced, then the neutral line that is shared between the two (not the neutral for each leg) will have no current, as the current will be going from leg to leg and not through the common neutral. However, since current is rarely balanced between legs, only the difference between the currents will pass through the neutral, and no more than the maximum current of one leg (say, if one leg is maxxed out and the other one with no load) then the common neutral will carry no more than the load from the loaded leg. It can get fancy with inductive loads, where currents and voltage do not always line up evenly, but I'm too rusty on this one to make any more statements.
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If it's setup as a center-tapped neutral like normal, and you are drawing an even 30 amps on each 120V leg at the end of the cable run, the current on the neutral is zero. They balance each other out. Worst case is 30 amps on the neutral if one hot leg is unloaded.
But you do not want that neutral to go open under any circumstances, because very bad things happen when the loads get unbalanced - the voltages start swinging.
Some old generators can be jumpered to provide true 60A 120V with the windings in parallel. But then you can't use that 10/3 cable, more like 4-3 - and voltage drop is a more serious problem...
--<< Bruce >>--
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Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
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On Sat, 23 Apr 2005 04:17:34 GMT, Bruce L Bergman

mine can be.

6 gauge will work just fine.
i
AWG Dia-mils TPI Dia-mm Circ-mils Ohms/Kft Ft/Ohm Ft/Lb Ohms/Lb Lb/Kft NormAmps MaxAmps
6 162.02 6.1721 4.1153 26251 0.3951 2531.1 12.585 0.0050 79.460 52.501 59.866