Wiring code -- across attic floor joists

Usually you will already have a 2x4 running perpendicular to stiffen the joists, which you can use as a running board, or if you need to, install your own.

Also, the Nec defines an attic as being "accessible", if it has permanent stairs or ladders to access it. If you just have a scuttle hole, it's not considered accessible, and you can staple the cables perpendicular on top of the joists except for within six feet of the scuttle hole

Right idea but you staple the wire to the side of the running board. Then you are not walking/crawling on it and if you do put some decking up there, it is not sitting on the wire.

OR if the destination of the wire allows it, run them on the underside of the rafters so you won't tread on the cables if and when you have work to do up there.

I've seen lots of houses here in AZ where they just lay the wire on top of the joists, no nailing board. Just a few staples here and there to hold the wire down.

well if you EVER want to store stuff up there, your far better off to run the wires thru the joists...

when this home was built in 1950 they ran the wires on top of the joists and when 3 years ater i decided to add a floor it was a big hassle

The Nec still requires running boards if you are within 7 feet of the floor joists

I'm sure they did it to piss you off

If these are actually the bottom chord of a truss (2x4) DO NOT DRILL THEM.

The trick for decking an attic with wires on top of the framing is to add 1x2s purlins to space the deck up 3/4" and clear all of the wires.

I had to do this in my attic. It also gets you by that "6' from the hole" problem.

If you have decent insulation up there you may even want to use thicker stock so you are not crushing your insulation.

Okay, thanks. That's good to know.

The access to this attic space has a strange type of access. There's a small door in the back of a closet on the second floor, and behind that door is the top of a stairway that runs up from the first floor to the second floor. The were a couple of boards nailed across the sloped stairway "ceiling"(?) joists to form a makeshift ladder effect, and I can climb up those makeshift crossboards into the attic. I nailed better boards across the stairway ceiling joists to make it easier to climb up and into the attic. I guess that means it does have an existing makeshift ladder up into the attic, and I guess that may make it "accessible" for NEC purposes.

I think I'll just use running boards anyway, and I'll also stay away from the area within 6 feet of the access hole. That should cover me -- meaning whether the attic is "accessible" or not.

That's a possible option, and I'll keep that in mind depending on where the circuits are running.

That's good to know too. No part of the attic space is more than 7 feet high, so I'll use running boards even if I run the wires across the rafters above.

I'm sure that I will never want to make this into a storage area of any kind. And, given the other options that are available (such as using running boards), I am not going to do any drilling or running of wires through the joists.

Agreed but if it's a truss, can't you run the wires thru the truss (or should I say chords) with no drilling involved? That said, I doubt they used trusses in 1950 home construction but I'll let the OP tell us.

Thanks everyone for all of the replies and suggestions. I just decided last night that I am going to be doing this, and I am going to be starting the work this morning. It was great to be able to post the question last night and then wake up this morning and all of the answers that I needed are right there waiting for me to read. This is an excellent Usenet group!

It would take 2X8s in my "attic".