Member Discussion

What Do You Mount Power Supply Panels Onto When In LAN Or Electrical Rooms?

Doing a retrofit where we are removing the old access control panels and the power supply panel in a good-sized LAN/Electrical room. The old power supply has a primary 115VAC feed and two transformers for supplying power to mag locks at 4 doors. Re-using 115VAC power feed and verifying existing fire alarm interlock, etc, etc.

We are replacing the old power supply with a new Altronix AL600ULM; the sub-contractor we are working with says that the old power supply as well as the old Brivo panels should never have been mounted directly onto the drywall, but should have been mounted onto a piece of fire-rated plywood which was first attached to the drywall surface.

While I didn't disagree, especially once I saw the big holes left by the large toggle bolts used to hold the old power supply to the wall .. much bigger footprint than the AL600ULM.  However, I looked around and saw primary power breaker/distribution panels mounted directly to the drywall walls. So was the fire suppression control panel and power supply on another side of the room.

So, the questions are: 1. How does everyone mount power supply and control enclosures in LAN/electrical rooms?  Do you  attach directly to the walls, or do you first install piece of plywood?

                                 2. Is the drywall painted with a fire-retardant paint, or is the plywood or panel board already treated                                    to be fire-retardant?

I am thinking back to some of the retrofits I have seen recently, and unless there was an existing demarc wall that had some spare real estate on it to mount an access control enclosure or power supply, most have been mounted directly to the drywall with heavy duty toggle bolts.

Thanks for your input and opinions.

There is nothing wrong with hanging your equipment directly to the drywall. I would make the case that the sub didn't want to mess with mounting the equipment to the drywall as that takes at least a few more minutes than just screwing to plywood. Lazy I would imagine. I have used plywood before that was painted with fire retardant and these always came with a small bottle of paint to cover up any holes you make to keep the rating. In a retrofit we typically just mount straight to the drywall unless there are going to be lots of panels then we will mount fire rated plywood.

We cut few 2'x4' plywood backer boards and have them on the ready.  We paint them gray to look nicer.  I had one inspector ask me if that was fire proof paint on the plywood.  I responded firmly, yes sir!  I thought it was funny then.  Still do.



"Fire rated plywood" makes no sense, ask any fire marshal.

The reason to use plywood is because you cut a big enough sheet to span across two studs. Once the plywood is fastened to the studs then you can mount the much smaller power supply anywhere on the plywood. 
Sounds to me like the sub contractor is trying to make his case for using plywood more official. I will agree that mounting a bigger sheet of plywood onto studs and then mounting smaller power supplies and enclosures onto the plywood is the correct way to do an install.


Mostly putting a layer of sheet rock on a wall takes care of any fire rating issues and then you add plywood to make installing equipment easier. If there is no fire rating needed you install plywood instead of sheet rock.

The only way that plywood would help prevent fire is if the fire started in the equipment attached to it. Which is incredibly unlikely. If they want the room to be fire retardant, then they should coat the room accordingly. Most of these coatings can be applied to drywall. It doesn't have to be plywood.

That being said, in past jobs when mounting equipment we did tend to include a partial sheet of wood that we hung from drywall/studs and then mounted to. We actually kept 4'x4' sheets in stock, pre-painted, at one job. The summer help or facilities folks would paint them when they had nothing else to do, and then they were easy to grab and go. It served two purposes:

  • It's easier to secure a sheet of plywood with 4-6 anchors and then wood screw to that than it is to put an anchor in for every piece of equipment. 
  • It was a good way of indicating what belonged to us. Everything on that backboard was clearly demarcated as belonging to a specific subsystem, so it was easier to say "Don't touch that/screw to that" than when enclosures were mounted all around.

Plywood almost always if New Contruction, but if it's an existing building we are adding to, or upgrading it's kinda hit and miss. 

None of the companies I've worked for in the past ever put Plywood in the quotes. If a customer really wanted it, it was sort of up to them to provide it for us.

It is nice, I prefer to mount to Plywood just for the sake of being easier, if I could I'd probably use it all the time. Some situations make it impossible, or not practical.

Like OP mentions, I have seen specs that require plywood backing boards to be coated with intumescent/fire resistant paint on both sides, but that stuff is expensive, often at over $100 per gallon!

That requirement seems kind of silly anyway, but it is worth checking the other backing panels to see if the existing stuff is painted this way, to match.  

I think the plywood sheets are primarily used because it is much easier to use a wood screw into plywood than to drill for anchors into sheetrock. Also, wood is much better at holding devices. The big difference you can attach the plywood directly to studs, which makes the whole setup much more secure. You can use full sheets of plywood to allow many devices to be attached simply. We generally see these types of rooms covered on all walls with 23/32in panels.