I’m laying chipboard in my loft and have uncovered a main electricity wire routed over a beam rather than under it. I want to put a groove in the beam so I can lay the chipboard without damaging the wire.
I do not intend working near the wire with the electricity turned on; I will turn the electricity off. Much of the SDMB far outclasses me in intellect, but I’m not that stupid.
The wire is quite tight so I cannot move it out of the way (maybe 1 cm or so), so perforce I must work close to the wire. I have a long saw and a jigsaw and a drill.
Just to emphasise: I do not intend working near the wire with the electricity turned on; I will turn the electricity off.
Me, I’d use a hammer and chisel. Much less chance of accidentally severing the wire than using power tools, IMO. If you’re careful (and your chisel is sharp), you can actually carve the groove directly under the wire.
Ditto. In this case, power tools are not your friend. I’d also use this method. Either that or trace the wire, disconnect it, rip it out and rewire it with a new wire in the appropriate location so you don’t have to chisel it out.
Once you’ve notched the beam and tucked the wire in, you must protect the wire with a steel plate so you don’t accidentally drive a nail or screw into it when you’re fastening the chipboard. (I’m assuming you’re converting an unfinished attic into a more usable space.)
Most hardware stores have ready-made plates for this purpose in the electrical department, or you could use a blank “4x4” box cover. Either way, the idea is you’ll hit steel and back off, rather than nailing into the wire and having some combination of: you getting shocked, the circuit being knocked out, an electrically “hot” nailhead is waiting to sting whoever brushes against it, or a fire.
Maybe not now, but think ahead to later when you decide that sliding piece of chipboard needs to be secured. The plate you need to put in costs less than $1, IIRC.
Something else to do would be to find the two (or so) closest peices of hardware that are keeping it in place. If you remove them it might give you enough slack to push the wire out of the way while you are working under it.
Oh, and make sure when you notch the beam that you don’t need to be concerned about it now being weaker.
I assume this is a cieling joist, not a beam in the construction vernacular. Notching a beam would be a no-no, and I wouldn’t do it to a load bearing joist. If you must do this, at least scab on a doubler for 2’ or so, screwed and glued.
Notching at the edge weakens a structural member MUCH more than a hole through the middle. There are standards in the building code, but IIRC, the hole should be no closer than 25% of the member depth from either edge.
If I am visualising what you are wanting to do correctly, neither Australian nor NZ regulations would allow you to do it.
Notching a load bearing member can seriously weaken it as has already been mentioned.
Creating a wooden groove and pushing a wire into it would be considered a fire hazard.
Putting a thin metal plate over the wire would not be considered sufficient protection from nail guns and the like and would not be allowed.
Regulations here require electrical wires to be placed through the middle of wall and ceiling framework. Where that is not possible, regulation conduit must be used to conceal the wire on the outside of whatever it is that you are constructing.
Code issues aside, I am lazy. Give the lazy guy the hard job, and he will find the easy way to do it.
I would notch the underside of the chipboard to accommodate the wire. This can be done with power tools, and a few careful measurements.
Before you can notch a foot of the beam, I will have the chipboard laid.
I’d be kind of inclined to drill a hole through the beam, attach junction boxes on each side, and cut and reroute the cable, with all appropriate connectors and stress-relievers in place.
You definitely need to cover the wire with a piece of steel, and not just over where you are notching the board. Any place where someone might put a nail in the future needs to be protected by steel, so you might need to run a bunch of plates all along the wire’s path. 30 years from now someone might nail the chipboard down, then 20 years after that someone might nail some other flooring material on top of that, so nails could end up virtually anywhere. You pretty much need to protect the entire run of wire. It’s really just a handful of steel plates which will only cost a couple of bucks, so it’s no big deal.
I don’t like the junction box idea. You really shouldn’t hide junctions under floors or behind walls.
Good point - it’s actually a code violation to have “buried” or hidden junction boxes. They need to remain accessible for inspection and repairs, and that’s impossible if a floor has been laid on top of them.
The j-boxes don’t need to be directly on either side of the beam/joist. You can put the boxes anywhere and use the proper length of cable to connect them together. When I re-route wires like this I place the j-boxes high enough that they’re not covered by insulation and where the owners can see them readily. This means they’re usually on one of the 2x4 vertical truss braces. The added benefit to cutting in some j-boxes is easy access in the future if you want to add a light, outlet or fan in the attic.
Electrical work like that has to be done by a qualified electrician over here. I’m trying to avoid expense. I’ll definitely go for the metal plates though. Thus far I’ve been notching the chipboard instead.
Not sure if I’m properly picturing what you want to do, but rather than groove out the chipboard, I’d build up the beam on each side of the wire. Lay a firring strip along the top of the beam on each side of the wire, and do the same on the tops of the other beams that will support the rest of the chipboard. Easier than notching it out, especially with the tools you’ve listed.
Ditto what others have said about covering the wire with plate, etc.
I wonder what you mean by ‘main electrical wire’? Do you know what it feeds? How old is the house?
I suspect that this is something a previous owner added, and probably feeds an extra outlet he put in. I would find both ends of it first. It may not even be hot.
