That's a converged networks wiring closet, from enterprise networks solutions provider Foundry Networks.
According to an article in Network World, the temperatures in wiring closets typically used for IP phone AP power supplies can be so high as to be risky.
The problem is that in the typical wiring closet, you've got PoE (Power over Ethernet) switches to light up the phones as well as to support Ethernet traffic; UPS (Uninterruptible Power Supply) equipment to allow switches to run during a power outage, and the fact that all this equipment in a confined space produces a cumulative heat effect.
The article quantifies this effect. Start with a product such as Cisco's non-PoE 24-port Catalyst 3750 LAN switch. That generates 176 BTUs of heat per hour.
Then if you add the PoE option, the switch will spike up the BTU burn rate to 534 BTUs of heat per hour.
But wait. What about the UPS? That adds another 80 to 100 BTUs of heat per hour, in a small space at that.
“In certain climates, you could have very high humidity, with the ambient temperature getting above [104 degrees]," Patrick Ferriter, vice president of marketing for IP PBX maker Zultys tells Network World's Phil Hochmuth.
Sounds bad enough, but depending on your set-up inside that wiring closet, things could get even worse for you.
“If you have an IP PBX which has built-in gateways, and if you have a lot of analog connections — FXS boards that provide ring voltage — it could start to get even hotter,” Ferriter tells Hochmuth. "It’s going to be hotter than a traditional key system for sure.
"There are places where it does get hot," Ferriter adds, "and you’re going to have problems if you don’t have air conditioning."