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[Andrew Broughton]

Don't know what I'm talking about when it comes to installs, but is PVC conduit an option?

[Kevin Maxwell]

It depends on if you are talking about new construction or a major remodeling of the church or just installing a new system. As others have said you need to know what the local laws are regarding this install. There is something going on right now that may change the classification of networking cable with power over it POE (Power Over Ethernet) that will change how and who can install it.

Conduit has a lot of advantages but it is NOT EASY to pull more wire in existing populated conduit. Even if a pull line was left in there. It becomes a tangled mess and I have even seen the internal conductors of wire get broken when pulled thru conduit. Now I assume it was pulled incorrectly. Wire is usually rated as to how much tension it can take being pulled. And unless you have a pull line taking that stress instead of the wire, it can damage the wire. In my experience it is best to have a properly sized conduit for what is being pulled. And that needs to have taken into account all of the bends. I like to have empty (except for a pull line) spare conduit for what you will need to run in the future. Also having mid pull access points in the conduit if possible is a really good idea.

And don’t let anyone intermingle alarm wiring in with any A/V wiring. I think it is against the code but I have encountered the intermingling of alarm wire with an out of conduit run and there was all sorts of crosstalk with that stuff. You could hear the cross talk in the monitors with all of the sound system off, the amps at the time were in the sound booth and speaker wire was entangled with the alarm wiring.

If this is new installation that cost sounds like for a rather large place. Or they are trying to run conduit in an existing building and that is very hard to do. But really good electricians have surprised me as to what they can accomplish.

If the wiring doesn’t have to be in conduits there are things to take into account when running them. If the space is a plenum space then special wire must be used. I did some work in one church where we asked if above the ceiling was a plenum space and they said it was. So we got plenum cable, it turned out that it wasn’t a plenum space, maybe they really just didn’t understand the meaning of a plenum space and they thought it was. Do you know what a plenum space is?

I would never run wire outside of a metal conduit where construction could run a sheetrock screw thru it. And if it is above a ceiling we never just lay it on top of the ceiling it must be hung above it and not entangled in any other wiring. I did some work in a school where all of the low voltage wiring is in cable raceways above the mostly suspended ceiling. There was a lot of cabling in those raceways, including a lot of fiber.   

Good luck with this project.

[Caleb Dueck]

What do you mean by the wiring only lasting 15 years?

I could see the type of wire/cable or quantity needs changing.

Conduit, if done right, will out last the cabling.  Say Cat5e or RG video cabling is pulled now, and 15 years from now it's all pulled out and replaced by multi mode fiber.  If there is no conduit now, that switch to fiber is going to go from a fairly simple re-pull to a major ordeal. 

Edit to add- many conduit runs only have a few wires (IE to each speaker location, or each lighting control lication).  With the trend of wiring shrinking in size rather than expanding, such as 64x mic/line to a single Cat6A or multiple RG6 to a single fiber optic, future re-pulls are often not too terrible.  Re-pulling a single mic/line out of 64 - good luck.

When sizing conduit, I generally use a calculator for conduit fill, then upsize by one. 

When there are multiple types of cabling (audio, video, lighting control - not fire/alarm/etc, that's separate), such as from FOH to the main rack location - I would often use multiple conduits, such as (3) 2".  While higher cost up front, it's much more likely to re-pull a wire or two through one of those, easily. 

Speaker locations - say there is a mono subwoofer cluster.  I may size conduit for X number of future 10/2 runs in case they add subs in the future, to account for the re-pull and extra cabling.

Another refinement is to think through every location having a home run, vs a large diameter home run from a pull box, with multiple small "spider" runs from that to each location.  Designing conduit well is a bit of an art form, especially on larger projects. It's a balance of up-front conduit cost, up front labor, future labor, future cabling, and cost savings of not using plenum wire in some cases as was pointed out.  It's easy if not careful to paint yourself into a corner. 

[Caleb Dueck]

Don't know what I'm talking about when it comes to installs, but is PVC conduit an option?

Not really.  Pull string on the inner bends can cut into and create a big issue fast.  At least the new construction church projects I've done were all metal conduit. 

[Troy Warner]

Conduit, if done right, will out last the cabling.  Say Cat5e or RG video cabling is pulled now, and 15 years from now it's all pulled out and replaced by multi mode fiber.  If there is no conduit now, that switch to fiber is going to go from a fairly simple re-pull to a major ordeal. 

Edit to add- many conduit runs only have a few wires (IE to each speaker location, or each lighting control lication).  With the trend of wiring shrinking in size rather than expanding, such as 64x mic/line to a single Cat6A or multiple RG6 to a single fiber optic, future re-pulls are often not too terrible.  Re-pulling a single mic/line out of 64 - good luck.

When sizing conduit, I generally use a calculator for conduit fill, then upsize by one. 

When there are multiple types of cabling (audio, video, lighting control - not fire/alarm/etc, that's separate), such as from FOH to the main rack location - I would often use multiple conduits, such as (3) 2".  While higher cost up front, it's much more likely to re-pull a wire or two through one of those, easily. 

Speaker locations - say there is a mono subwoofer cluster.  I may size conduit for X number of future 10/2 runs in case they add subs in the future, to account for the re-pull and extra cabling.

Another refinement is to think through every location having a home run, vs a large diameter home run from a pull box, with multiple small "spider" runs from that to each location.  Designing conduit well is a bit of an art form, especially on larger projects. It's a balance of up-front conduit cost, up front labor, future labor, future cabling, and cost savings of not using plenum wire in some cases as was pointed out.  It's easy if not careful to paint yourself into a corner.

Our construction is a complete remodel only three walls of the original building are left. We have a new roof using an open ceiling design and could even cut the cement and run underground. I totally understand not wanting to risk a screw through the wall. Is there are reason why we can't run pvc in ceiling versus metal conduit?

Thanks for all the input everyone.

Troy

[Brian Jojade]

Don't know what I'm talking about when it comes to installs, but is PVC conduit an option?

I highly doubt that a PVC option would lower the price.  It may even increase the price a bit as it can be more labor intensive to deal with.  That's part of the reason you see metal conduit in most installs.

[Andrew Broughton]

I highly doubt that a PVC option would lower the price.  It may even increase the price a bit as it can be more labor intensive to deal with.  That's part of the reason you see metal conduit in most installs.

PVC is about 1/3 the price for the same diameter. As for labour, I would be surprised. Certainly the biggest issue is the "wearing" of the plastic when pulling a lot of wire through as was mentioned earlier. Hadn't thought of that. I've seen PVC pipes used in floors, under stages and places where the pipe can be very large with very little pulling resistance.

[Erik Jerde]

PVC is about 1/3 the price for the same diameter. As for labour, I would be surprised. Certainly the biggest issue is the "wearing" of the plastic when pulling a lot of wire through as was mentioned earlier. Hadn't thought of that. I've seen PVC pipes used in floors, under stages and places where the pipe can be very large with very little pulling resistance.

If you’re dealing with a straight shot in a void then 4” PVC can be a quick and easy way to get a chase in place.  That’s usually plumbing pipe btw.  Once you have to start doing 90s, offsets, and other more complicated routing pvc gets real hard.  Plus the wear issue Caleb mentioned.  Also, pvc doesn’t protect against nails/screws.

Having done a fair bit of plumbing pvc, some electrical pvc, and quite a bit of emt conduit (for a non sparky that is) I’d run emt every day of the week given the choice.  It’s just a lot easier to work.  Cleaner too.

[Jonathan Johnson]

When considering whether to run conduit or not, also consider the space that the cabling is being installed in.

In some spaces, conduit may be required. Plenum space -- like the space above a false ceiling, if used for air handling -- requires that exposed cabling have plenum-rated insulation and jacketing. If the cabling is not plenum-rated, then it will need to be in conduit. (The plenum rating is based on the combustion and smoke generating characteristics of the insulation and jacket material. Plenum-rated cables are usually more costly.)

If penetrating a fire-rated wall or floor, an approved penetration method must be used so the fire rating is not compromised. The most cost-effective is to stub a piece of steel conduit through; where the conduit penetrates the wall it must be sealed with proper sealants to maintain the fire rating, and the ends of the conduit (if not terminated in an electrical box) must also be sealed where the wire exits. If you have fire-rated walls in your facility that the conduit will be passing through, a not-insignificant part of the cost could be attributed to maintaining those fire ratings. (PVC conduit requires a more advanced sealing method that can close off the penetration if the conduit melts.) Sealing is necessary not just for slowing the spread of fire, but also for reducing the spread of smoke.

Also consider the labor cost of installing AV cabling without conduit. The cabling must be supported or fastened properly to the structure, about every 3 feet. Holes must still be drilled. Laying cable on top of ceiling tiles is inconsiderate of other trades (resulting in higher charges from them) and may be a violation of building codes (requiring corrections).

[Stephen Swaffer]

Don't know what I'm talking about when it comes to installs, but is PVC conduit an option?

NEC 352 Rigid PVC Conduit

NEC 352.12 Uses not permitted
 (E)  Theaters and Similar locations, except as provided in 518.4 and 520.5

The exceptions being that it can encased in 2 inches of concrete.

The reason (as I understand it) is smoke generation in case of fire-same reason NM/romex is banned in these locations.

So it doesn't matter how its used.

[ProSoundWeb Community]