Conduit fill question

[Iron-Iceberg]

I have 3/4" emt run in my shop. It has a 3 wire #12 awg, 20 amp 120v circuit for two plugs, and a 3 wire #10 awg, 30 amp 220 circuit for my drill.
I just picked up a welder that needs a #8 wire 50 amp circuit. Can I fit this in the same 3/4" emt run?, will that be too much fill? Would I have to derate the circuits?
I tried to read the nec codes on this but I'm getting a little lost and i don't want to miss something.
Thanks for any help.

 

[pattenp]

If I did my math correctly you're okay adding the 2 #8's and a #10 ground. I assume you'll use a #10 for the ground. And I assume all the wire is THHN, existing and new.


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[Iron-Iceberg]

If I did my math correctly you're okay adding the 2 #8's and a #10 ground. I assume you'll use a #10 for the ground. And I assume all the wire is THHN, existing and new.


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Yes I'm sorry I forgot THHN.
That is another question do I need a ground with the emt? Or can I just run the 2 #8 hot wires?

 

[pattenp]

The EMT can serve as the ground, but you need to make sure it's bonded properly. Personally I prefer to run an equipment ground wire.

 

[Iron-Iceberg]

The EMT can serve as the ground, but you need to make sure it's bonded properly. Personally I prefer to run an equipment ground wire.

Yea I would rather run a ground too. As long as I have enough room.