How To Calculate How Much Wire I Need For Pre-Wire

[wkearney99]

I think the biggest problem most non-tech savvy people have with automation is neither they nor the installers know what it ought to be like to have automation in a home like theirs.  Way too often the installer techs just flat don't know how to live in a house of that size.  And the homeowners don't feel like being taken for a ride while the junior installer tech gets billed out at premium rates while being taught how to live in their kind of house.  I know I sure don't like it.  And that's exactly how several friends with Crestron and Savants systems have felt about it. 

But that's probably a conversation best had on it's own thread, not here.
 
My point of interjecting it here is that over-wiring may prove "a waste" if you don't utilize it.  But not doing it will make you feel like an idiot for passing up on the chance to do it when you discover it's going to cost double to do after the fact.  Yes, you will feel like you're head's gonna 'splode trying to figure it all out.

 

[Del91574]

Last year I pulled 5 miles of wire in my 4000 sf home under construction.   It was my first attempt at this kind of thing.   Here are a few of my lessons learned:
 
1) install your cans and chases first.  I used 6-42 inch cans and 3-28 inch cans.   Probably a bit of overkill, but I have the room in my closet.
8) A dirty secret is that cat 6 wire is much stiffer and about twice the volume of cat 5 wire.   It only costs about 10% more, but it fills up your conduit and J-hooks fast.   I ran a combination of cat 6 and cat 5.   I switched to cat 5 on some items mainly because it was a lot easier to run.   Time will tell if that was a good decision.

I'll just toss this out there:
 
1. Planning out the routing is important, however, pulling the cabling into the cans would be the last item I'd worry about. I can't comment about what your infrastructure and whatnot is, but with that many cans, I'd start thinking a rack probably would've been a better fit.
 
8. It all depends on the Cat6 you buy. The splineless or small stranded C6 is actually easier to work with than some C5E. The diameter really isn't too different than C5E.

 

[bucko]

I duplicate the house using Visio and map the wires. Then in Visio it will calculate lengths.
 
My 200sqm house took 4000m of wire.
I am doing a project now which is a 500 sqm villa and it will take 15,000m of wire.
 
Don't skrimp on wire!!!

 

[pete_c]

Personally here have personally over guessed for my wire stuff and helping friends wire up their homes.  It is inexpensive to do this.

 

[apostolakisl]

Put in conduit and only pull exactly the wire you need when and if you need it.  And conduit always allows you to put in the latest and greatest 5, 10, or 50 years from now.  i have lots of empty conduit in my house.  Conduit only costs about 20 cents per foot for the 3/4 grey electrical stuff and it easily bends with a little warming up from a propane torch such that it almost becomes flex conduit.  At 20 cents per foot it is actually cheaper than running a whole bundle of "just in case" wires.
 
I'm not suggesting, however that you pull all your alarm system contact wires.  I don't really see that paying off.  But I would run conduit to places you might want to automate, like for automatic blinds and locks.

 

[wkearney99]

Meh, conduit is not cheap and certainly no faster to install.  The connectors and boxes are what kill you.  That and the inside diameter of the conduit often leaves you less room than had you pulled cables.  I'd only recommend installing it somewhere that would be a supreme pain in the ass to access after the fact.  I ran some from outside wall outlets, in addition to the CAT5/coax.  I figured those would be such as hassle to access later than it was worth the belt-and-suspenders approach.  Now that we've been in the house for a while I know they'll NEVER get used.  This goes back to my mention of REALLY thinking hard about how the spaces are going to get used.
 
I suppose if you're good with installing it and you accept that it won't hold much then conduit is certainly something to consider.  Just don't fall prey to the notion that you can add things into it later.  That typically never works unless it's a large conduit with next to nothing already in it.  Otherwise the only safe plan is to remove whatever's in there and pull all new cables.  Which becomes a chore if there are any corners or pull boxes along the route.
 
The reality is no two houses are alike and each will require it's own fine-tuning when it comes to deciding what to install and how.

 

[pete_c]

Yup here in one house that is elevated on cement put LV conduit in the cement of the home office going to the middle of the room for the desk which I am using today.  (HV and LV go to a box in the cement / tiled floor). 
 
I also put conduit in the cement floor under a custom wood built in to the wall media area which I use today. (well more here and there that I use today and all in the cement floor).  I did just pull cable (extra) for everything else.
 
Recalling now it was a PITA because I had to do it and wanted it done in a particular fashion.  I didn't ask the contractor though; just told him what I was doing.  (never micromanaged the build as I only directed my comments to the GC as I watched).
 
The LV telephone guy did daisy chain all of the telephone wires and I had the GC do it all over again removing all that was done.
 
Thinking about this now and anything that I didn't like I would typically have the GC do it over again.  I only really just voiced my concerns in a pleasant manner. (maybe he thought differently though).

 

[apostolakisl]

Meh, conduit is not cheap and certainly no faster to install.  The connectors and boxes are what kill you.  That and the inside diameter of the conduit often leaves you less room than had you pulled cables.  I'd only recommend installing it somewhere that would be a supreme pain in the ass to access after the fact.  I ran some from outside wall outlets, in addition to the CAT5/coax.  I figured those would be such as hassle to access later than it was worth the belt-and-suspenders approach.  Now that we've been in the house for a while I know they'll NEVER get used.  This goes back to my mention of REALLY thinking hard about how the spaces are going to get used.
 
I suppose if you're good with installing it and you accept that it won't hold much then conduit is certainly something to consider.  Just don't fall prey to the notion that you can add things into it later.  That typically never works unless it's a large conduit with next to nothing already in it.  Otherwise the only safe plan is to remove whatever's in there and pull all new cables.  Which becomes a chore if there are any corners or pull boxes along the route.
 
The reality is no two houses are alike and each will require it's own fine-tuning when it comes to deciding what to install and how.

 
How many wires doing you think you are going to run to that outlet behind your desk?  That is the point.  You only run what you need and need typically is only 1 or 2.  3/4 conduit will hold 4 plus wires easily (a coax a fiber and a couple cat6).  It is rare that you need more than 1 wire to a location anyway, maybe 2.  Certainly if you have a high intensity spot like behind your AV center you are going to go for bigger conduit and that is spot I would definitely put conduit because those needs are always changing.  I put 2 inch there.  Furthermore, you don't need boxes for low voltage.  You have a low voltage "ring" to terminate your wire into just the same as if you had no conduit at all.  There is always something there to secure your wall jack to unless you like the high end finish of  wire poking through a bare hole in the wall.  For the most part, I had my electricians use the combo high v/low v boxes so I ran the conduit to the box that was already needed to be there and kept the wall clutter down by having a single double plate instead of multiple single plates.
 
I did my house with conduit everywhere.  It is probably a wash on time consumption as compare to saying running 5 wires everywhere (coax/fiber/2 cat5/6/whatever else).  Furthermore, you avoid that obscene bundle of wire, 95% of which go unused.  And what to do you do with all of those unused wires.  Spend like a week terminating them all or just coil them all up and shove them in the wall?  And don't forget to label all of those 200 wires.  And then don't forget about that whole day wasted fishing a wire someplace later on because your needs changed.
 
And I almost forgot about that wire that the sheetrocker screwed into.  This doesn't happen with conduit since the wire isn't even there yet.

 

[wkearney99]

Not sure it's necessary to be argumentative with wording like "obscene".  Should we get into quibbling over which approach is worse for the environment?  What with all the plastics (petroleum) involved.  I mean, really?  
 
All those little bushings and nuts for conduit add up on cost (surprisingly more than you'd expect).  I suppose it could be argued as a wash either way, cost-wise.  I've found it handy to know there's wire already present and simply light it up as needed.  I remove the wall plate, replace the blank with a keystone insert and put a jack on the cable.  Then ring it out back at the panel and cross-connect it as needed.  The same things would happen with conduit, after I'd spent at least another hour wrestling with putting the cables through it.  I preferred to front-load my effort by putting the cabling in once and forgetting about it.  It's bad enough finding time to do the simple part of terminating it, adding more time to pull the wires isn't how I want to approach it.
 
Yes, you can terminate conduit at low voltage rings, and deal with the hassles of keeping them square when the drywall crew comes through.  But don't try using them when the walls are going to get spray foam insulation.  Again, most houses are unique and their wiring plan would do well to keep that in mind. 
 
Given the plethora of devices that can be wired these days I've been finding using two or more is not unusual.  The TV has an Ethernet port, as does the DVR.  Connecting them directly back to the switch avoids putting another switch (and it's power plug) at the TV.  That and it's been handy to use a port for an additional wireless access point for guest access.  And before someone chimes in with PowerOverEthernet, that introduces its own set of additional complications and expense.
 
Yes, you certainly CAN go the route of putting in a barebones amount of cabling.  Me, I figured out that after a lifetime of cheaping out like that it was going to work better for me to put in a bit more and be done with it.  I'd advise anyone else to decide where their comfort level sits between the two.

 

[IVB]

5 days ago I tore down the wall that holds the elk main board and chose to put in conduit instead of just rerunning existing wiring. The reason was both to allow future additional wiring, and also to provide an additional layer of protection against nails / screws. I used conduit fastener every 16-24" to keep it square, plus screwed it into LV boxes so it doesn't come loose. I needed two 3/4" conduit at 80% fill so I ran four.

I'm not saying what I did is moar better than you guys. I mean, it is moar better, but I'm not going to say that. (I'm joking, I'm joking! Unless I'm not.)

 

[IVB]

Et voila. There was a wall here Friday morning. Then I got annoyed and tore it down. Not because of wiring, I just realized the old owners didn't actually remove the old walls, just added on. We had 3 layers of wall. (plaster / lathe, plywood, sheet rock). I also found out we have 3 floor tops above the solid wood subfloor wasting 2 inches of height but that's a huge project.

 

[wkearney99]

Ah, the joys of older homes.  I never cease to be appalled at what abominations get discovered during what we assumed was going to be a simple job.  But 2" of lost floor height, wow, that's bad.  And I'm guessing all the trim and doors would have to be redone as well?
 
Our old house (ca. 1950) had tile (done in 1996) in the kitchen laid down on 1/4" plywood (not backer) over TWO layers of linoleum.  Which, of course, I only discovered when it became clear the new fridge that was delivered wasn't going to be able to drop down into the offset where the old fridge was resting.  There was just enough clearance in the face frame of the cabinet above to allow for trimming.  
 
Or that the framing for drywall attached to the outside walls were literally just 1" furring strips tacked onto the cinder blocks.  Talk about adventures with chasing wires, with stuff getting caught on sloppy mortar joints...  To say nothing of the complete absence of insulation.
 
I've come to regard conduit as only "necessary" if it's going to be a place that will be impossible to chase wire later.  Because fishing wire back through conduit isn't usually any easier than going through an empty wall cavity.  But as you show in your picture, there's not always a clear chase all the way up a cavity.
 
If you know you're going to be putting a specific amount of wire in, then why bother using conduit for it?  Why not just run it by itself?  I did it that way and only ran the smurf tube to places where any additional wiring would really be a hassle.   

 

[IVB]

Ah, the joys of older homes.  I never cease to be appalled at what abominations get discovered during what we assumed was going to be a simple job.  But 2" of lost floor height, wow, that's bad.  And I'm guessing all the trim and doors would have to be redone as well?
 
(snipped)
 
If you know you're going to be putting a specific amount of wire in, then why bother using conduit for it?  Why not just run it by itself?  I did it that way and only ran the smurf tube to places where any additional wiring would really be a hassle.   

Yep on doors / etc. 2 layers of linoleum plus the current floor we love is on top of 3/4'. WTF?

Regarding conduit, partially as I didn't trust myself to leave well enough alone, partially to protect against screws. I'll feel the resistance of the smurf tube. Honestly it only took 12 hours to run all 5 tubes including the time to screw in the lv boxes, fasteners, etc. In the grand scheme of things, I've pissed away far more than 12 hours on automation stuff. Just in June. This way I'm protected a little more than without it. I suck at patching sheetrock, if y'all are good at it this might not be an issue for you.

 

[apostolakisl]

Not sure it's necessary to be argumentative with wording like "obscene".  Should we get into quibbling over which approach is worse for the environment?  What with all the plastics (petroleum) involved.  I mean, really?  
 
All those little bushings and nuts for conduit add up on cost (surprisingly more than you'd expect).  I suppose it could be argued as a wash either way, cost-wise.  I've found it handy to know there's wire already present and simply light it up as needed.  I remove the wall plate, replace the blank with a keystone insert and put a jack on the cable.  Then ring it out back at the panel and cross-connect it as needed.  The same things would happen with conduit, after I'd spent at least another hour wrestling with putting the cables through it.  I preferred to front-load my effort by putting the cabling in once and forgetting about it.  It's bad enough finding time to do the simple part of terminating it, adding more time to pull the wires isn't how I want to approach it.
 
Yes, you can terminate conduit at low voltage rings, and deal with the hassles of keeping them square when the drywall crew comes through.  But don't try using them when the walls are going to get spray foam insulation.  Again, most houses are unique and their wiring plan would do well to keep that in mind. 
 
Given the plethora of devices that can be wired these days I've been finding using two or more is not unusual.  The TV has an Ethernet port, as does the DVR.  Connecting them directly back to the switch avoids putting another switch (and it's power plug) at the TV.  That and it's been handy to use a port for an additional wireless access point for guest access.  And before someone chimes in with PowerOverEthernet, that introduces its own set of additional complications and expense.
 
Yes, you certainly CAN go the route of putting in a barebones amount of cabling.  Me, I figured out that after a lifetime of cheaping out like that it was going to work better for me to put in a bit more and be done with it.  I'd advise anyone else to decide where their comfort level sits between the two.

 
 
You don't need all of those connectors for low voltage conduit.  Just dead end the conduit into the hole.  I had my whole house spray foamed and it worked fine.  Unless you use closed cell foam, which almost no one uses, the open cell foam is nothing to pull out.  You do it with your index finger.
 
Not sure where you are going with the "obscene" comments and environment stuff.  200 unnecessary wire vs running conduit and only necessary wires is kind of like, who knows which is less on the environment.  I'm guessing conduit as compared to all that copper.  The fact is, whichever you put in, it is probably going to sit in that house for the next 100 years, so it isn't like a land fill thing either way. 
 
The main thing with conduit is the piece of mind that you can always change what you did without a single 5 foot drill bit, fish tape, drywall knife, joint tape, joint compound, floating, sanding, texturing painting, event..  Once the sheetrock goes up, it is a major PITA to correct even a single change to the plan.  Conduit is one of the simplest and cheapest future proofing opportunities you have when the walls are open.

 

[wkearney99]

Given the staggering amount of CAT5/6 wire that installed it's pretty likely there won't be a way to continue utilizing it for the foreseeable future.  So putting in conduit and then also running wire through it really does seem like a pretty wasteful approach.  Both in time/labor and money.  Where's the data on the number of times anyone's ever bothered to pull wire back out of conduit and replace it?  I'll grant you, however, that an improperly installed or defective cable can be replaced with a lot less trouble if it's sitting in conduit.  But at what point do you spend against the risks or just go with more wire in the first place, instead?
 
As for 'simple', just where do you think all those conduit ends are going to terminate?  Just how much square footage is it going to take to bring all of them into some sort of managed space?  While also maintaining proper bend radius requirements (for both the wire and the conduit)?  Yes, for perhaps a dozen you can bring them into the side of a box.  Otherwise you're going to have to put in much larger boxes, or more of them.  Spending more money and requiring space for them.  And end up with hassles with pulling through multiple boxes.
 
I suppose it's a matter of perspective.  Small jobs, small approaches, planning against wild variations the future might hold.  But, hey, have at it.  I'm not saying don't use conduit.  I'm saying for most residential situations it's not something that seems necessary.