CHCC Remodel: Conduit

The other day, I updated you on the renovation we’re in the middle of at Coast Hills. I figured it might be helpful to give you some details on specific sub-systems. Today, we’ll hit the one that has plagued me from the day I walked through the doors the first time almost 5 years ago: Conduit. 

Skimping on Conduit

Based on the lack of conduit in the original building, one might conclude there was an EMT shortage back in 1994. There was not a single continuous run of conduit from the tech booth to the stage. Nope. Not one. We had our electricians cobble a few runs together a couple years back, which enabled us to get most of our signal wire in conduit, but most of those runs were close to 250’ by the time it was all said and done. Keep in mind, the tech booth is about 90’ from the stage—albeit on the balcony. 

We had cables draped over the edge of the balcony for cameras, and all our audio cables were run above the decorative walls on the side of the room. Part of my goal for the remodel was to put in more conduit than I could imagine using. 

That might seem wasteful at first, but keep in mind that conduit is relatively inexpensive, and there’s a lot we can’t imagine right now when it comes to technology. I never like to have all my conduit full on day one; that really doesn’t leave any room for growth. I also didn’t want future tech guys to curse my name the way I have whoever laid out the conduit the first time…

Doing the Calculations

It might seem like figuring out how much conduit to install is like black magic—only a few know how to do it. But it’s not really that hard. There are a few pieces of information you need to know; how many cables you need to run, and their outside diameter (OD). Once you know that, you can do some quick math to figure out how much area each one takes up. Next, figure out the permissible area of your chosen conduit size, and do some division to figure out how much of it your cables use up.

Or, you could just do what I do and use a conduit fill calculator. 

The best fill calc I’ve seen is from CommScope. It’s an elaborate spreadsheet that will let you fill a conduit with multiple types of cables with different diameters, and it tells you how full various sizes of conduit will be. I did some mild modifications to it and pre-filled the ODs for the four types of cable I’m doing on this job. That way, I don’t have to keep looking them up. You can find the OD spec for a cable on the manufacturer’s website. 

Count the Cables

I built another spreadsheet to count how many cables needed to run from where to where. For example, from the stage to the booth, I currently need the following:

  • (4) 20A circuits
  • (2) Analog Audio
  • (4) Digital Audio
  • (8) Cat5s
  • (8) Coax (SDI and MADI)

Based on that, I punched the quantities into the calculator. I learned I can combine the audio cables into one easily enough. Those six would be about 25% in 3/4”, 15% in 1” and under 10% in 1 1/4”. The eight coax measured out about the same. The eight Cat5 add up to the biggest section, almost 30% in 3/4” but only 16% in 1 1/4”. Based on that, I decided that I could use four 1 1/4” conduits to run power, audio, coax and Cat5 (each in their tube). To plan for future growth, I doubled that count, and added two 2” for good measure. 

Again, the big expense in this job is trenching the floor; materials are cheap after the hole is dug. But it’s really expensive to add more later.

Run Conduit Everywhere

The time to run conduit is when the building is open. Since the underside of the balcony tech booth is open, I had them add five conduits on each side to connect the pull boxes on the back wall to the front wall. I also had them add four new runs to connect the new pull boxes. New conduit runs to the tech booth in our community room, which we use for overflow a few times a year, and we ran conduit to our cry room for the TV in there. Each of the lobby TVs had a conduit run as well. 

At this point, the conduit is a structural element. 

At this point, the conduit is a structural element. 

Inside the booth, I have three 12”x12” boxes with custom panels on them. I had 36 D-Size cutouts cut in the panels so I can populate them with whatever I want. Connecting all these boxes is a ring of six 1” conduits. Again, I don’t expect to use more than three right now, but it’s never easier to put in conduit than now when the booth is being built. I also have conduit coming down from the upstairs booth to the downstairs one, along with big (2 1/2”) conduits for the 26 pin cable for the cameras. 

Don’t Skimp on Conduit

I’ve said this before and I’ll say it again. Don’t skimp on your conduit runs. On a job the size of ours, conduit install can easily add tens of thousands of dollars to the job. That seems like a lot of money. However, I’ve had to have the guys come back and add one or two runs here and there when the building is not torn up, and it’s not hard to spend $2,000-3,000 for a few runs. Now that seems like a lot of money. 

You get one chance to get conduit in the building when it’s open. After that, you will either fight the building for the next 10-15 years or enjoy how easy it is to add cable. The choice is yours!