Thanks for the reply. Sorry, the hot tub GFIC is 240v, not sure if I clarified that initially. I intentionally chose the GFIC specifically because I thought it would provide a bit of safety for the entire structure.
OK. that makes a bit more sense. However, as Wylie pointed out, you're putting that GFCI in the wrong place; GFCIs are not designed to protect "structures"; their purpose is solely to protect PEOPLE. And while we're on the subject... It's "GFCI" (for "
Ground
Fault
Circuit
Interrupter"),
not "GFIC", as you consistently mis-type it.
I could always just have used a normal 50a disconnect, but thought this would be better. It is not feeding a hot tub (don't have one), but it was designed for a hot tub, it is only feeding the shed. I bought this new just for this purpose.
Is it already installed? And if so, where?
The proper place for such a disconnect is in/at/on the detached structure (i.e., the shed) itself, not 100+ feet away on another building. Part of its raison d'etre is so that, in the event that you suddenly have a "problem" in that detached structure, you can
quickly remove all power to the building with a single handle throw. It is (reasonably) presumed that for you to notice such a "problem" in time for disconnecting power to do you any good, you'd already be in/near said building. And besides which, as always, the primary goal of any safety device is to protect people, not "things". So again, that's the place to put the control.
Whenever I do electrical work, I Always do it above and beyond "code". Like running 10awg to 20a outlets for example. I don't do hack work, never have. That isn't my style. If you saw the electrical setup in the workshop I built, you'd probably be surprised. 400a service, 200a single & 200a 3 phase. Impressive # of outlets, and Def future proof. But I digress..
Ummm... OK. That wasn't exactly clear from your initial post; but I'll take it at face value for now. In any event, that's all the more reason to NOT spoil your track record with this project.
As for the sub panel, it is because it's much easier to run new circuits from there to the rest of that side of the house than to try and drag connections thru where they enter the house right now. 1 piece of 1 1/2" greenfield vs who knows how many 1/2 or 3/4". Not lazy, just would rather work smarter than harder, and to enlarge that would be much too much work ATM.
What other circuits
besides the one going to the shed were you planning on running from that sub-panel? ISTM that any existing circuits in the house would by definition already be run to the vicinity of the main panel(s). Are you planning a lot of additional new work not related to the shed? If not, then there is simply no reason for the sub-panel. And even if so, I have a hard time envisioning how that last 20 feet of wire pull could be so much of a PITA as to justify cobbling up what I presume would be a nice new 400A/twin-panel service installation.
Yep, I mistyped, 4 not 3 circuits in the little panel down there. I seem to have left out some vital info, sorry it was late and I was exhausted from working up on the roof all day. Bummer not to be 25 any more, things slow down a bit..
Understood -- and I'm in the same boat (I'll be 39 for the 24th time on my next birthday
).
Let me re-phrase the plan to make it clear. New 400a service in 2 panels. One of those feeding a 120a sub in the basement. That one is going to be feeding out the back thru the wall to a box mounted on it with the 50a 240v GFIC connected.
As alluded to above, unless that sub-panel is ALSO feeding (a goodly number of) additional branch circuits in the house itself, it has no reason to exist. And if it
IS feeding several other circuits, why did you not just move one of the new "Main" panels over to that spot, if the wiring runs would be so much easier from there?
Secondly, there is simply no good reason to go through that exterior-mounted box/breaker/GFCI; and doing so is just asking for trouble (more splices/connections, more opportunity for corrosion, etc.). Once the feeder cable leaves the main panel, it can (and should) go DIRECTLY to the shed.
This then proceeds down to shed, (using above mentioned copper wires) which has a little 6 place panel in it, which is going to have 4 circuits, 2 20a 240's and 2 20a 120's.
As long as we're discussing the shed's sub-panel... If I were you, I'd use a somewhat larger (as in, more branch-circuit slots, if not more load capacity) panel there. Do I really need to point out that installing a sub-panel which will be chock full the day you finish the project runs directly counter to your "future-proof" goal? Concomitantly, that larger panel can (and should) have a "Main" breaker in it to act as the local disconnect; hence you kill two birds with one stone.
Please help me with understanding the ground rod situation. I thought that all grounding had to be done thru the panel/breaker, because if there was a ground path other than the GFIC, it would eliminate the protection?
To further clarify (I hope) what Wylie said, the ground rods connect (indirectly) to the bare-copper (or sometimes green) "Equipment Grounding Conductor" found in pretty much every junction box you've got (at least presuming a reasonably modern electrical installation). They (and the EGCs themselves) are there strictly as a safety backup; and if all is right with the world, no current will EVER flow through them.
But in the context of a GFCI, "Ground" refers to (unintended)
leakage currents (to ANYWHERE), which is what the GFCI is designed to detect. In a 120V circuit, it does this by comparing the current flow between the "Hot" (black) wire and the "Neutral" (white) wire; the "Ground" (EGC) wire has nothing whatsoever to do with it. If these two currents do not match VERY closely (within milliamps), the GFCI trips and causes the feed from the "Hot" wire to be broken (i.e., "Interrupted"). The point here is, since that "leakage" current COULD be going anywhere (the GFCI neither knows nor cares), one such possible route is through a person (such as one holding a defective power tool and standing in a puddle, for example) -- which, obviously, could be lethal.
A 240V GFCI works similarly, but compares the currents on the two "Hot" legs. This is yet another reason why you do
NOT want that GFCI "upstream" of the shed's sub-panel. Any 120V loads run off that sub-panel will necessarily cause an imbalance between the two hot legs in the feeder, thus tripping the GFCI.
Thinking about it, I needed to take a look at what I bought again, because I know that 6awg copper wire was more than sufficient per my calculations at the time I bought it.
If you limit the feed to the shed to no more than 60 Amps, AWG 6 will suffice, provided that it is NOT type NM-B (which it surely would not be) and has insulation rated for at least 75°C (90°C would be better, but is not actually required).
After checking, I see that I have a 50a not 60a breaker, it's a "Square D QO Spa Pack 50 Amp GFCIGFI breaker with enclosure",
This implies that you have NOT as yet installed that stuff. Good. Don't.
Also, 50a is more than sufficient to feed the shed, even with the AC running, which is 15a 240v, I seriously doubt I will pull anywhere near the rating of the circuit. It looks like if I did have a 60a circuit, I would have needed to run 4AWG wire.
Not by my abacus. Granted, bigger is always better; but for 60 Amps @ 240V over a 240-foot (round trip) run, you'll need 25,800 circular mils to hold Voltage Drop to the recommended 3% limit. AWG 6 gives you 26,251 CM (cf.
http://www.engineeringtoolbox.com/awg-wire-gauge-circular-mils-d_819.html, which is (just barely) enough.
[The BBS software is nattering at me that the message is too long. So I'm breaking it here. Continued in next message...]
Dark at around 5 again.