fishing wire thru fire blocking
#1
02-06-23, 10:50 AM
fishing wire thru fire blocking
Not sure if this is an electrical question but since I was running electrical wires I figure an electrician might have run into this problem before. When running wire for overhead lighting I came across what I assume is fire blocking between joists. I attempted to drill a 1 inch hole thru the block and hit metal at some point. By means of the holes I put in the ceiling for the lighting I can see both sides of the fire block and there is no metal visible on either side. Does anyone know whether this block would consist of two pieces of wood with metal in between? I'm not sure what I'm dealing with here. I could get a bit that would drill through the metal but then I would have to have wire sitting on sharp edges of torn metal.
#2
02-06-23, 01:59 PM
Group Moderator
Where in the blocking are you drilling specifically? I'm guessing you've hit a nail if your drilling near the edges of the board. Always keep the possibility of electrical, plumbing, gas line, ducting in mind because you truly never know what is buried in walls sometimes. Copper or aluminum conductors cut pretty easily and may leave easily identifiable chips on your drill bit. A nail tends to grab spade or twist drills so you can often feel it as a pulsing when drilling but continuous contact with steel can be a nailer plate, pipe (water, sewer, gas...) or HVAC duct thought the steel in residential ducting is quite thin and easy to pop through.
Horizontal joist bays generally do not have fire blocking. If it's the floor for a room above it's common for there to be blocking between the joists for strength. If it's a solid piece of wood blocking the entire bay then it's usually nailed in place along the two vertical sides.
Measure in to the blocking from both sides to a known location like the edge of your access holes. Then measure the distance between your two marking locations. Compare your measurements You should find about 1 1/2" of wood in the middle. If it's bigger than that the size it can be a duct chase or something else needing further investigating.
Horizontal joist bays generally do not have fire blocking. If it's the floor for a room above it's common for there to be blocking between the joists for strength. If it's a solid piece of wood blocking the entire bay then it's usually nailed in place along the two vertical sides.
Measure in to the blocking from both sides to a known location like the edge of your access holes. Then measure the distance between your two marking locations. Compare your measurements You should find about 1 1/2" of wood in the middle. If it's bigger than that the size it can be a duct chase or something else needing further investigating.
#4
02-06-23, 02:16 PM
Group Moderator
Good info from Dane. 
I have worked in many houses that had cats or firestops in the walls.
I've never seen firestops in the ceiling.
There is typically X bridging.
If it was solid bridging.... I'd severely doubt any metal would be used as part of it.
I have worked in many houses that had cats or firestops in the walls.
I've never seen firestops in the ceiling.
There is typically X bridging.
If it was solid bridging.... I'd severely doubt any metal would be used as part of it.
#5
02-06-23, 02:50 PM
Thanks for responding. I realized that it isn't fire block. I do see some X bridging in there. The joists run the length of the room but because the distance is too long a cross beam or cross joist runs perpendicular to the joists. This is what I'm trying to get through. I'm running into some type of metal probably halfway through this piece. Should I get a drill bit that will go through it? I'm not sure what I'm dealing with. I have eight lights, four on each side. I would be able to get wiring across the joists with minimal damage to connect the four on each side, but I need to get across that beam or whatever it is, to connect the eight together. I've drilled in three different places and there's definitely metal. As I said in my original post, I am able to see both sides of the beam and no metal is obvious so I'm thinking a doubled up 2x8 with some type of metal in the center. But why?
#6
02-06-23, 04:22 PM
Group Moderator
It sounds like you've found a beam as PJ mentioned. Often a plate of steel is sandwiched between lumber or pieces of lumber are fit inside the side pockets of an I beam. Either way it's probably thick steel (more than sheet metal).
My first suggestion is to look for another way to run the wire. Any chance you can sneak around the end of the beam or run the wire through a wall and then pop up into the ceiling on the other side of the beam?
How good is your access to where you need to drill the hole? If you do need to go through the beam then read up or watch some videos on drilling through steel. If using twist drills you start with a small hole about 1/8". Then step up to larger bits until you get a hole the size you need. Smaller drill bits can be turned faster but as you move up to larger bits run the drill slower and apply a firm, steady push.
My first suggestion is to look for another way to run the wire. Any chance you can sneak around the end of the beam or run the wire through a wall and then pop up into the ceiling on the other side of the beam?
How good is your access to where you need to drill the hole? If you do need to go through the beam then read up or watch some videos on drilling through steel. If using twist drills you start with a small hole about 1/8". Then step up to larger bits until you get a hole the size you need. Smaller drill bits can be turned faster but as you move up to larger bits run the drill slower and apply a firm, steady push.
#8
02-06-23, 05:29 PM
Ok, thanks! I'll have to rethink about how I'm going to get around this. From what I'm seeing I think everything you've said is correct. I appreciate the help.
#9
03-26-23, 02:25 PM
Sorry this response is so late. The problem I had was at my daughters house in Virginia and I am back home in Colorado. Just thought I'd reply so those who responded would know what I actually encountered in that project. Pilot Dan was correct. I drilled thru a 2x8 and hit a steel plate, then another 2x8by and another steel plate, and then another 2x8 and finally bust through. A set of colbalt bits and a number of extensions is what it cost me. As long as I saw metal filings coming off I knew I would eventually get through it. Verys disappointing to run into a second plate. The biggest problem was widing the hole thru the steel to get my wood bit through. A lot of binding and at one point I thought I wouldn't be able to pull my colbalt bit out of the steel plate. I really appreciate the thoughts and suggestions offered. Most times the advice or suggestions I get on this site are what enables me to get a project done. Keep up the good work in helping us DIYers.
