OK electricians

nowires · Nov 30, 2014

OK electrician guys I am totally confused. But have also learned a lot. I just canâ€™t get the math to work out
So here is the problem
6 - #6 2 / 220 50 amp circuits
3 - #8 1 / 220 40 amp circuit
3 - #10 grounds
So I have over 6 conductors so that put me in the 70% fill of conduit. I did the math and came up with 2.11 square inches. I am coming up with 2â€œ conduit

Is this right. According to the conduit fill chart I should be able to use 1.25â€ conduit

Any help would be cool

Cole1 · Nov 30, 2014

1 1/4 is what I came up with for the min. size. Are you planning on running EMT to the box's/device from your panel?

nowires · Nov 30, 2014

Cole said:
1 1/4 is what I came up with for the min. size. Are you planning on running EMT to the box's/device from your panel?

Yes I am

Cole1 · Nov 30, 2014

EMT is sufficient ground no need to throw your money away just have the device pigtailed to the box. We only pull grounds when its spec'd in pipe or if we had to use flex somewhere.

nowires · Nov 30, 2014

That is what I was figuring. The thing that threw me was the amount of conductors in the pipe and the fill rate. According to NEC I can only fill the pipe 70%. Is that right. I will have 9 conductors.

!ton327 · Nov 30, 2014

it all depends on the calc and pipe size and derating of wire maybe a little more info would help how long is the run and what you are doing?
:beer:
and 50 amp you can get away at # 8 thhhn if its not a long distance or draw under 50 amps

nowires · Dec 1, 2014

!ton327 said:
it all depends on the calc and pipe size and derating of wire maybe a little more info would help how long is the run and what you are doing?
:beer:
and 50 amp you can get away at # 8 thhhn if its not a long distance or draw under 50 amps

Here are the runs
1 50 amp for plasma cutter 35 ft run
2 50 amp for Air compressor 58 ft run
3 40 amp welder 72 ft run

The plasma I am going to draw all of that and will be for extended time periods on a CNC table
The air compressor is a 5 HP motor pulls 28 amps, but the manufacture recommends a 50 amp breaker
Welder I was already planning on #8 and 40 amp breaker

99redtj · Dec 1, 2014

Pipe fill is based on 40 percent fill,any more than that and it gets harder to pull with the more bends you have

Murkman · Dec 1, 2014

Refer to the NEC. Check out both the Motor section and welder sections in the code.

nowires · Dec 1, 2014

99redtj said:
Pipe fill is based on 40 percent fill,any more than that and it gets harder to pull with the more bends you have

Pretty straight forward. 2 45s between pull boxes. No single pull is longer than 20'

BUILTnotBOT · Dec 1, 2014

If you plan on expanding bumping it to 70% to save a buck it will bite you.

If your pinching pennies on conduit price, oversize it with the thought of expansion and run it in PVC. Take your time and make it look nice. Your going to need a grounding conductor. You'll be buying ground for pig tails anyways....

and so you know, 250.122C all you need is one #10 for all those circuits, as long as they are in the same conduit.

To each his own. If I was bidding a job I'd do minimum, if it was my place with thought of expansion... which almost always happens... I'd oversize.