On Tue, 19 Nov 2019 20:56:25 -0800 (PST), trader_4
wrote:

On Tuesday, November 19, 2019 at 11:11:04 PM UTC-5, trader_4 wrote:
On Tuesday, November 19, 2019 at 10:33:25 PM UTC-5, Jim Joyce wrote:
Hi folks,

I'm planning to run a new electrical circuit out to a storage shed in my
back yard and I'd like some help with the details. I'm the homeowner and
I'll be doing most of the work myself, but I want it to be safe and up to
code.

1. I have called 811 - Call before you dig. They'll be coming out on
Thursday of this week to locate and mark all of the underground utilities.


2. I will be using a licensed electrician to connect the new service to the
existing service, but other than that final step everything else is on me.
I have experience with switches and fixtures, but not with the other
aspects of the project.

Permit? If you're going to get an electrician out there anyway, might
be easier and not much more for you to just dig the trench, let them
do the rest.






3. The rest of the 120VAC circuits in my home are 20A circuits, so by
default I'm planning to make this new circuit 20A as well. I believe a
single 120VAC circuit should be fine for both lights and receptacles out
there. The biggest load I can envision is possibly running a miter saw,
which is rated at 12A. Just in case I take that saw out there, I think a
15A circuit might be stretching it thin.

Having extra capacity isn't a bad idea. Any chance you;d need 240V
for anything?




Q: Any issues with a single new 20A circuit for both lights and
receptacles?

Not that I'm aware of. Make sure it's on a GFCI. Probably best
to put a GFCI receptacle as the first point in the shed. That way if it
trips, you can reset it there.


Rethinking that, you also need a disconnect at the shed. They have
GFCI that are just that, no receptacle and I think they can be used
as the disconnect. So, you could use one of those. Or a switch,
then a GFCI receptacle.











4. Web calculators say I should use 8AWG wire for this circuit because the
run is about 120 feet, from the exterior of the house to the exterior of
the shed. I'm planning to buy 3 solid copper wires, 8AWG, in colors white
(neutral), black (hot), and green (ground). This is instead of a packaged
cable such as Romex because I think it will be less expensive to buy
individual wires and because it might be easier to pull 3 wires through
conduit than to pull Romex.

8 sounds like over kill to me, don't know what calculator you're using.
Generally, 12g is used for 20A. Since it's a 125 ft run, I'd go down to 10g.
You can run individual conductors, but you can just use UF cable and it
will be easier/cheaper.





Q: Any issues so far? I know the black and white wires need to be 8AWG, but
does the green (ground) also need to be 8AWG? Am I looking for wire labeled
THHN or is it something different? I'm buying everything at the local Home
Depot.

THHN is not rated for wet locations. You need THWN. The minimum ground
size for 20A is 12g.






5. I'm planning to use conduit versus direct-bury wire. Web calculators
seem to indicate that 1/2 inch conduit is fine, but I was thinking about
using 1 inch to make pulling the wires easier. I'm also open to using 3/4
inch conduit.

Use UF, skip the conduit.




Q: Does code mandate a minimum conduit size? (Conduit fill) Does common
sense suggest a different (larger) size? Also, does conduit get assembled
as dry press fit, or does it get glued, section by section?

Yes, yes. If you use conduit, I'd go with 3/4". It gets glued together.






6. The house has a 240VAC breaker box on the exterior wall, with no room
for an additional breaker, so I'm planning to buy a small 2-circuit
sub-panel that I'd attach to the house, right next to the existing 240VAC
panel. I would ask the electrician to connect the sub-panel to the existing
240VAC panel.

Q: I assume the electrician can create a new circuit from the 240VAC panel.
Are there any issues with that plan?

Should be OK, depending of course on what other loads are on the existing
panel.






7. The conduit will be buried by using a trencher. My understanding is that
electrical conduit needs to be buried at least 18 inches deep, whereas if I
went with direct bury I'd have to go 24 inches deep.

That's correct.





Q: Any advice on the use of conduit versus direct bury cable?


***

Once I get power to the shed, I'm good with the project after that. I
appreciate any help I can get with the questions above or anything I might
be overlooking.

If you have to pull a permit and have it inspected, which would be the case
in most locations, I would consider doing the trenching and having the
electrician do the rest. He has to come out and do a subpanel anyway,
installing a couple receptacles and light isn't that much more and you know
it will pass. Or at least get it quoted that way before deciding.


He gets a huge huss in the NEC if this is a 15/20a GFCI protected
circuit on dwelling property. (12" burial depth and a break on the
disconnect). I would still want a snap switch (but I can be a hard ass
:-) )