I have just run electric to my work shed. I ran 120v from 220v using a sub panel. Now when I turn on a saw the lights dim and the saw runs slow in the beginning building up to speed. Can anyone hepl?

I ran the sub panel, which has slots for 2 breakers, from a 40amp dual pole breaker which was used to run an old pool pump using the existing wire which is "AWG 12 cu2 CDR with AWG 12 ground type UF-B 600 volts" the distance is about 75 feet. Additionally, I have the sub panel set up to run two 110 20amp breakers. Thanks in advance for any additional help

Too small of wire gage limiting current (amps) feeding the shed.

Why did you run only a 120v sub-panel??
What is the total distance?
What size wire did you run?

Copied from another thread:

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Originally Posted by GONZOSMC

I ran the sub panel, which has slots for 2 breakers, from a 40amp dual pole breaker which was used to run an old pool pump using the existing wire which is "AWG 12 cu2 CDR with AWG 12 ground type UF-B 600 volts" the distance is about 75 feet. Additionally, I have the sub panel set up to run two 110 20amp breakers. Thanks in advance for any additional help

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So you ran this sub-panel with #12 off a 40A breaker?? Are you aware how mismatched this is?

Can I strongly suggest you have someone qualified come out and look at this. I think there is more wrong here than meets the eye.

IMO... Rip all that out and start over before you burn something up.

#12 is only rated for 20amps. With Continued use you are really asking for trouble.

Take it all out, run the correct wire (#8 for 40amps unless V drop issues) along with the eq grounds so that's this is safe.

You'd almost be safer running a large gage extension cord to the saw!

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Originally Posted by stanfortyman

Copied from another thread:

So you ran this sub-panel with #12 off a 40A breaker???? Are you aware how mismatched this is??

Can I strongly suggest you have someone qualified come out and look at this. I think there is more wrong here than meets the eye.

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I was going to say the same thing! We need to start taking electricity more serious! Some think our work is just wirenutting conductors of the same, but it's more than that.

To name a few things involved with our day to day work:

1. Bonding
a. enclosures and equipment
2. Grounding
a. enclosures and equipment
b. separately derived systems
c. intersystems
3. Dwell calculations
4. Motor and transformer calculations
5. Parallel circuits
6. Using volmeters/ Megohm meters/ ammeters
7. Calculations (More):
a. box fill
b. conduit fill
c. conductor sizing
d. VD
e. Conduit bodies
f. angle pull
g. u pull

8. Swimming pools
9. Fire pumps
10. Solar Photovoltaic
11. Referenceing the NEC/ NFPA70/ Local codes/ UL/ Osha/ International code... etc
12. Knowing designated standards for equipement (Ul or other)
13. Electrical wiring in general:
a. layout/ design


And much much more.
To add: Much much :)