Premises-Powered Broadband Communications Systems

Article 840 covers premises-powered broadband communications systems — the current mainstream of fiber-to-the-home and similar services. Here the incoming signal is typically optical (carrying no dangerous power), and the active equipment at the customer end, the optical network terminal (ONT), is powered by the building's own electrical system, often with a battery backup for phone service during outages.

Because the hazard shifts to the premises side, 840 covers the ONT, its power supply and backup battery, the premises-side wiring it feeds (which may include powered communications and even limited-power circuits to end devices), grounding and bonding of any metallic members, and cable listings. It's the newest of the Chapter 8 system articles and reflects how broadband delivery evolved from powered copper toward optical service with locally powered terminals.

When it applies

Article 840 covers premises-powered broadband, the modern fiber-to-the-home setup where the signal arrives as light but the network terminal, the ONT, is powered from inside the home. That flips the old model: the provider no longer feeds power down the line, so the building's own supply and often a backup battery run the terminal.

Common mistakes

• Forgetting the ONT needs a reliable premises power source and, where required, a backup so a power outage does not kill the phone line.
• Skipping the grounding and bonding of the network terminal and any conductive cable entering the building.
• Confusing the powered premises equipment with the utility side and mis-applying who is responsible for what.

In the field

On fiber installs I make sure the homeowner understands the ONT rides on their power now, and if the code or the service calls for a backup battery, I install it and label it. When the grid drops, that little battery is the only thing keeping a 911 call alive.