So my shop foundation drainage project (3 weekends max) has now turned into a 6 weekend disaster. As far as I can tell, the previous HO, using bits and pieces of PVC he found here and there, pieced them together, ran 3 10 AWG and 1 14(?) AWG ground through it, punched a hole in the side of the shop, connected the sub panel, and covered the PVC with some driveway gravel. I'm just discovering this as I attempt to solve a water-entering-the-shop-at-grade problem. Obviously I have to fix this. The dilemma I'm faced with now is: "what size wire to use? do I need a service disconnect? where to bond the neutral in the sub?" The only problem I've solved so far, is yes, I know, it needs to be two feet deep. I'll probably go 3...
So the breaker at the main is a 40 amp double pole. There are 5 20 amps and a double 40 in the sub. I'm reasonably confident that each 20 in the shop feeds a pair of double-gangs (makes sense, lots of power tools), one 20 feeds the shop lights, and one....nothing. All the wiring in the shop is EMT, metal gangs, pigtailed with ground wire screwed to the gang, as well as a ground wire to the sub. I DO tend to run a lot of tools at once, chop/table saw with shop vac, compressor, grinder, stereo, chargers, 240 V planer and jointer. I've never noticed any lights dimming or wires getting hot. So clearly I need to get this line buried deeper, and through the side of building using the appropriate hardware. Trenching is not going to be a problem, and I have no problem with using the biggest PVC called for.
In the sub, the neutral is bonded to the bus bar in what I think is a (hole?) that will only take a 10 ga wire. There are 2 neutral bus bars (NOT BONDED TO GROUND!), and the other bus has what appears to be an empty lug which I think is where the neutral should go. Is my assumption correct?
The ground looks like a 12 ga to me, bonded directly to the panel. I'm assuming I need a bigger ground wire, should I bond the same way? Wouldn't I need to tap a bigger screw?
Given the load I described, I'm thinking a 40 amp in the main isn't enough, but I really can't afford the size/type wire needed for a 100 amp. Would a 60 amp double in the main be appropriate here? Let's say with the shop vac, planer, stereo, 2 shop fans, and lights, I'm pulling 40 amps +/- 5......(yes, my neighbors hate me. If they'd take their damned dogs in night, I'd consider turning the stereo off when I plane 1000 ft of wood).
Would 6, or even 8 AWG copper for the 2 hots and neutral be appropriate? run is 30 ft. 10 AWG for the ground? I'm trying to keep this in the realm of what I can get at BIG BOX STORE. My preference is copper.
Speaking of ground, in the main, ground and neutral are bonded, there's a single ground rod under the meter, and another independent ground rod bonded to the propane pipes 8 ft away. Propane is used for the furnace in the attic; it runs on 120V. Nothing else is hooked to the propane. Let's assume they're 8 ft down. The ground from the sub is bonded to the bus bar in the main with all of the other grounds. Reading all the opinions about needing a separate ground rod(s) for the sub is making my head come untwisted. Do need I need two rods at the sub? Do I bond them directly to the panel? While I have the ground open as part of the drainage project, wondering if I just sink two (will require a roto-hammer, soil is not soil it is weathered bed rock), and if it's an issue down the road, I just clamp on the wire. Or, is that just a waste of two copper rods?
All construction was "sometime in the mid 90's".
I've never had an issue with GFCI's in the sub tripping, even while standing in an inch of water in the shop (hence the drainage project), and running the wet/dry vac. I push the button every few months, and they test fine.
By my count, there are 6 breakers in the sub. Does that meet the 6-and-you-don't need-a-service-disconnect rule? Does the double-pole count twice and put me at 7? If not, would the standard disconnect used for an AC unit work here? Where to put it? Under the sub? Flush in the wall? Fused or unfused?
Yes, I know, I should call an electrician. But...this is burying a darned wire. Now if (when) I need Arc Faults installed, or a disconnect installed for my water heater, yes, I will call the nice electrician. Problem is, in my area, we had a little problem that resulted in the instant "removal" of about 2500 homes from the inventory. Rebuilding is in full swing, electricians even from 75 miles away are saying they can come give a quote in 2018 (I do have another project that I'm trying to get done, that does need one: I'm hoping to get a main panel replacement (currentone is a Westinghouse/Bryant) so I can run Arc Faults and baseboard heating, can't do that with the current panel, it appears to have been wired in the same hokey way as the shop feeder, and I want to keep my HO insurance). So, again, while I got the ground open and the jackhammer rented, would love to get correctly sized wires in to solve my immediate problem, as well as support my planned upgrade which realistically will occur in 18 months. Don't want to have to open my driveway again....