I would like wired Ethernet in my house, a couple weeks ago I asked about the risk of lightning when running it outside, I done some more research and found that my house has a cavity wall which means a gap filled with some insulation, my questions are:

1) Do I need internal or external Ethernet - I've read that PVC coatings on cables can 'melt' onto the insulation like 'soft chewing gum' so would external Ethernet be required, unless I could use some sort of conduit with internal Ethernet?

2) What device should I use for getting the cables up there - I was originally thinking some electrical fish tape going down attaching two cables and pulling 'em up from the living room to the loft but I've heard of magnets too would they work? I would ideally like a solution below the price of the fish tape I found at £15

Here are some pictures I took up there:

the white stuff appeared to be loose insulation, I had to move a 'bag' out the way to get to it, also note that I checked and there feels like a wall towards the camera and you can see a wall away from it

here's a shot slightly 'backwards' with the bag replaced

here's the area I'd be working with, space furthest away is the area where the insulation is, the wood slightly closer is on top of what I felt as a wall, the black wire is an aerial that the builders installed prior to us moving in, I wouldn't be able to fit a cable down there with it as it appears to sound like there's something under it and I don't want to have to redecorate (knocked on it), finally the thing on the other side of the cable is the ceiling

  • I can’t tell what I’m looking at in these pictures, and it’s impossible to tell you how to run the wire and what you’re going to run in to from one end to another. What I can tell you, is I don’t know where you’re hearing the PVC will melt. This is low voltage, low current wire. Unless you plan on setting t on fire, it’s not going to melt. Some building code may require riser cable between floors. Otherwise it is typically standard UTP Cat5e or 6 indoor cable. Good luck fishing any wire through insulation. And yes, it requires an actual metal fish tape. – Appleoddity Apr 28 '18 at 12:47
  • As long as your cables are not exposed to direct sunlight, moisture, or other elements, there should be no issue with running commercially produced low voltage cable inside a wall, "external" rated cable is not required. As far as techniques for fishing an insulated wall, there are hundreds, Google and Youtube can be your friend on that one, and practice, but your pictures don't really give a good idea of the scope of the job. Sometimes a "real" fish tape is necessary, sometimes you can use a metal measuring tape, sometimes wire pull sticks or a long drill bit, all depends on the situation. – acejavelin Apr 28 '18 at 12:47
  • @Appleoddity huh, so moisture or something won't get in and destroy the PVC coating? (I believe that's what the statement was referring to on a different website something about moisture causing it to look like it melted) – Stamp Apr 28 '18 at 12:50
  • Moisture by itself will not "melt" properly installed PVC insulated cabling, at least not in our lifetime, unless the cable gets damaged and the inner conductors are exposed. And by "moisture" I assume you mean humidity/condensation or occasional leak/drop, and not submerged for any length of time. – acejavelin Apr 28 '18 at 12:52

Using a wallfish will be tedious here. Get yourself a set of glow rods that can cover the distance. Usually a set of four will be more than enough for residential.

Make sure the kit you pick up has a "hook" attachment with it. It will make it very easy on the lower side to grab the glow rods inside the wall. Use riser or plenum rated cable. The only time I have seen a pvc jacket degrade was in direct sunlight. (Non UV rated) they don't melt, but fall apart when disturbed in this condition.

It's hard to tell what's going on in your pics, the first picture looked like cinder-brick to me. If that's the case you will need a hammer drill and masonary bit to get through it.

You will need a minimum of two people for this. Force the glow rods from top down, have the second person notify you when they see the rod through your drilled/cut-out outlet. They will be the one hooking the glow rod. Tape the cable to the rods and pull it back up.

It's not rocket science, but it can be frusterating if you have never done it before. Better buy the friend some beer ahead of time!

Note: Some areas under coding authority's require "plenum" rated cable for residential and office spaces. The reason is that non plenum rated cabling releases toxic fumes in structure fires. It's a couple of cents more per foot. But worth noting, if you can find it. it's not a bad idea to install plenum rated cable. Both riser and plenum have a small dense rope internally to help withstand the weight of the cables dangling over time.


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