Extending 20 amp circuit outside 100' +

Noble

I've wired my new shed located in back of yard with 12/2 wire and am looking to extend a 20amp line from edge of deck for an additional 50' to the new shed. I've found that the circuit is 20amp and the wire from the house to the edge of deck, existing is 14/2. While simply trying to test the shed wiring (which I am pretty sure is correct) the circuit kept tripping as soon as switched on. I know that the line from the house to the edge of deck needs to be replaced with 12 gauge, but the question is, is that the reason that the circuit is tripping or is it distance or is there something else.

Additional info: The only thing on the line at the time was a GFI on outside of house and what was wired in the shed. Originally it ended at edge of deck with a light for girll. That will have to be rewired. Also, I'll have to check the GFI at house of which I could not get the test and reset to work correctly. Figure I will uninstall that GFI and bypass to a new GFI down the line at the edge of deck. All switches and outlets in the shed are 15/20amp with a total of four switches. One for cut off inside shed, then three for lights, one being a motion detector.

Let me know if anything else is needed for info. All help is appreciated. Thanks!

Scuba_Dave

If you are trying to run a 2nd circuit to the shed that is a code violation
You can have one circuit
or a MWBC circuit for 2 circuits
or a sub-panel

The circuit tripping as soon as it turns on usually means a short somewhere

Noble

its a single circuit dedicated to outside. Nothing inside the house runs on it. I'm simply extending the line out to the shed an additional 50' plus the lines in the shed.

Scuba_Dave

I see, reread what you posted
Possible the GFCI is defective if it is older
Is the wire running underground to the shed ?
If the circuit breaker is tripping I'd say there is a short/something mis-wired

Noble

Tonight I'll remove the GFCI at the house as it is very old. I have not yet burried the cable as i was simply trying to test the wiring in the shed. My concern is the jump from 12 guage from box to old GFCI and then down to 14 guage to edge of deck, then back up to new 12 guage wire out to the shed. My hope is that the 14 guage wire is the problem, the only problem. I'll let you know what I find out tomorrow after removeing the old GFCI. Looks like this will be trial and error episode. DOH!

Scuba_Dave

Changing wire gauge would not cause the breaker to trip
Unless you went over the breaker value
The newer GFCI's are WR rated - weather resistant
I'm still using up my old stock of GFCI's
I've only had one outside GFCI fail due to exposure to weather in 15 years
But it does happen

Just make sure you upgrade the wire to #12 for the 20a breaker
Or downgrade to a 15a breaker
If you have a long run from the panel to the shed you can experience voltage drop -100' or longer distance
Not a problem except for some motors/devices & possibly CFL's if voltage loss it too great
And you would only run into it when you puller higher amps on the circuit