I’m planning on a wiring upgrade for my garage woodworking shop and some miscellaneous questions have arise that I was wondering if I could get some help with. (Cross-posting note: Some of these have been posed on another forum as well. I'm just trying to cover my bases.)
Here’s some background information:
- I’m in Alberta, Canada
- I’ll be getting the permits and doing the work myself, calling for inspection when finished
- I have a copy of P.S. Knight’s ‘Electrical Code Simplified Book 1 2006-2010’
- I have previously done some basic electrical work, but nothing approaching the complexity of this project
- My garage is attached to my house and is insulated, drywalled and heated (though usually only to ~5-10C when not being used)
- I plan on using surface mountings in the garage for this project.
- My main panel is in my basement and is 100A.
- While my basement is finished, most of the wiring for this project will mercifully be able to run through an insulated but undrywalled storage room. Only about 15’ or so will need to be routed through a finished area. Given the situation and some planned future renovations, I’ll be opening a portion of the ceiling for this portion of the run.
- In order to pass into the garage, the line will need to pass through the concrete basement wall.
- Based on information I’ve collected to this point the plan is to #6 cable from the main panel to the subpanel in the garage.
- The main panel will have a 60A double pole breaker and the subpanel in the garage is rated at 100A (but not because that ampacity is required – I just found that the 100A panel was less expensive and easier to find)
- I plan on GFCI protection for each circuit (either on the first receptacle in a circuit, or at the breaker if needed)
So, knowing that here are my questions:
1. Will the #6 cable coming through the basement wall into the garage fit into ½” conduit or would ¾” be required for this bit?
2. I'm a little be-dazzled with all the 'loomex', 'THHN', 'THWN', 'NM', 'Romex', 'SER', 'NMW, 'NMWU',' in the stuff I've been reading. I'm pretty sure what's needed for the circuits off the subpanel in the garage is 12-2 loomex (but confirmation on that wouldn't hurt). What I'm not sure about is what kind of rating/description/three-or-four letter acronym the #6 cable feeding the subpanel is supposed to have. Any help sorting this out would be helpful.
2. In terms of passing through from the basement cement wall into the garage, are there special requirements? I’m aware that the cable mustn’t be surrounded by insulation so will be careful about that part, but am just curious if conduit passing through from the garage side into the basement for a small distance (say 12” maybe) is sufficient. The conduit would run continuously from the garage side of the basement wall up into the subpanel.
3. Rule 12-518 of the 20th edition of the Canadian Electrical Code states that where cable is run on the surface of the wall and within 59" from the floor the cable must be protected from mechanical damage with wood or similar molding. Most of the planned circuits off the subpanel will be in & around this height. Regardless of whether or not they don’t require protection, I plan on using conduit. I’m having trouble getting solid information however, whether PVC conduit is permissible in this application or not? I’d rather use PVC than EMT if possible because of the cost and ease of working.
4. Two of the planned circuits will be dedicated, being used with just one tool/device in mind (for example one for my dust collector and one for my welder). I was wondering if it’d be possible to have the cables for these circuits share conduit with cable for other circuits. Rule 4-004(10) contemplates cables in continuous contact. Can cable for other circuits run inside the conduit carrying one or both of the cables for these circuits? Would the ampacity of the conductors need to be derated as a result? (The code talks about wires inside walls being in continuous contact but doesn't seem to discuss this issue as relates to conductor inside conduit.)
5. If, as mentioned in question 2, I rout cable for multiple circuits in one conduit, what is the recommended method for passing the cable not for that circuit through the boxes? Can they just pass through at the back of the box? If so, do they contribute to box fill calculations?
6. Would ½” PVC conduit be sufficient to run, say, three 12-2 cables?
7. I plan on using 12-2 for all the 120V circuits, as this simultaneously permits the circuit to use 20A breakers as well as creating the possibility of going to 240V at some subsequent point if required. However, a couple of the planned circuits will be 240V with a single dedicated duplex receptacle that will service a particular machine. I'm wondering if there'd be any value in using 10-2 for those, just in case I'd ever need/want to go have it be a 30A service after futurre upgrade to the tool at that spot?
8. I suspect the cable from the main panel to the subpanel needs to be 6-3 but am not 100% on that. Am I correct?
9. The usual ampacity-wire gauge correlations are what led to me concluding that #6 cable is required with a 60A breaker. However, information from a one person I consulted flies in the face of that conventional wisdom. The lingering doubt in my mind is that this is the only dissenting source, as everything else I’ve come across corroborates this usual correlation:
15 A...14 ga
20 A...12 ga
30 A...10 ga
40 A...8 ga
60 A...6 ga
80 A...4 ga and so on...
What this fellow said is that #6 copper is rated 55A at 60C and 65A at 75C , and NM cable (Romex) ampacity is limited to the 60C column. Many folks use the 'round up' rule and use #6 as 60A feeders. But, he cautioned that I’m likely as not to get gigged by the inspector, saying a subpanel is not a known load like a heating unit or motor load, where the cable is sized to the load, and a breaker can be rounded up to the next larger standard size if the requirement is between sizes - a panel is whatever load you put on it, so the round-up rule really doesn't apply. He cites info in the follwing link, which is similar to the NEC table:
http://www.armstrongssupply.com/wire_chart.htm
10. Is it possible to have a box in a run that’s present only for ‘future provision’ for that circuit? What I’m thinking here is just a loop of wire in the box, with a blank faceplate, in order to facilitate addition of an outlet later?
Are there any other questions you’d expect I should ask, but haven’t?