New answers tagged code-compliance
I don't think the use of these colours are standardised (outside of use in plain old-fashioned land-line telephone systems). I would disassemble the other end and see how the wires are connected up there. Most likely, two are connected to a push-to-make switch. If you are sure the system is unpowered, you could use a multimeter to check all 6 combinations ...
I wouldn't rule out the use of Sch40 PVC here. In fact I would consider a length of sch40 PVC glued to the hub of a PVC box all well fastened to the wall a far superior choice, and it's virtually allowed per 334.15(B) "...or other approved means..." EMT and metal boxes mounted to damp below grade masonary walls have way too many issues for me: possible ...
Yes drywall is rated for 24 oc.
You need to box off that floor joist. You can remove an section of the joist in the way. You then build a box connecting the ends of the cut off joist to adjacent joists with perpendicular ties of the same dimensions of lumber. 2X10's for example. These ties transfer the load to the adjacent joists and give you an opening for plumbing or duct work.
Not unless they are 2x12 floor joists and it goes exactly through the center. The maximum permissible boring in a floor joist is limited to 1/3 of the height of the joist (with a 2" minimum). See IBC 2308.8.2. Sistering the joists would not effect this restriction, as it is an issue of the structural integrity of the framing member - not an issue of the ...
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