The Phone, Cable and Fiber Boxes on the Outside Wall

Why this matters

The gray and beige boxes near the meter look like clutter, and crews treat them that way: painted shut, pressure washed until water runs inside, unscrewed so siding can go behind them, or left hanging with their ground wire cut. Each box belongs to a different provider, at least half of it is not the homeowner's to open, and the wire running from it to the electrical service is a safety bond, not a leftover. A cut bond wire or a wet interface is invisible until a storm, an outage, or a customer's internet goes down the day after your crew leaves and the provider's tech writes "damaged by contractor" on the ticket.

What you are looking at

 SIDING FACE, near the electrical service

      drop from pole (aerial)         drop clamp
       \                              on wall
        \___________________________[o]  12 ft
                                     |
   +--------+   +-------+   +--------+--+
   | PHONE  |   | COAX  |   |  FIBER     |
   | NID    |   | GROUND|   |  TERMINAL  |
   | telco  |   | BLOCK |   |  provider  |
   | side   |   | (may  |   |  sealed,   |
   | sealed |   | sit in|   |  laser     |
   |--------|   | a box)|   |  inside    |
   |customer|   +---+---+   +-----+------+
   | side   |       |             |
   +---+----+       |       fiber to ONT
       |            |       (inside or out)
       +---- bonding wires -----+
                    |
          to the electrical service ground
          near the meter (bonding point)

Not every house has all three. Many have a dead copper phone box left from years ago, a coax line, and a newer fiber box, each installed by a different company on a different day.

The three boxes and who owns which side

The phone network interface device (NID). A box, usually gray, where the phone company's line meets the house wiring. It has two compartments. The telco side holds the incoming line and a surge protector and is closed with a special screw or a seal; it belongs to the phone company. The customer side has a test jack and terminals for the house wiring; it belongs to the property owner. That boundary is the demarcation point, defined for wireline phone service under federal rules, and it is why the phone company repairs up to the box and the owner pays for anything beyond it.

The coax ground block. A small metal fitting, sometimes inside a plastic box, where the cable TV or cable internet line enters. The coax from the street lands on one side, the house coax leaves the other, and a copper wire screwed to the block bonds the cable's shield to the building's electrical grounding. The incoming side up to the block belongs to the cable company.

The fiber terminal. A sealed box where the provider's fiber optic drop ends. In some installations the optical network terminal (ONT, the device that turns light into an ethernet signal) is outside; more often it is inside, with a power supply and sometimes a backup battery. The outside box is the provider's.

The bonding wires. The phone protector, the coax block and sometimes the fiber terminal each have a copper wire running to an intersystem bonding termination near the meter or to the service ground. NEC 250.94 and the Chapter 8 communications rules (2023 edition, as adopted) require that connection and keep it short. It gives lightning and fault current a path to ground outside the house rather than through the wiring inside it.

What each trade tends to damage

Siding crews. The boxes have to come off the wall for new siding to go behind them. The temptation is to unscrew them, let them hang, and remount them on the new siding. The NID is one box holding both the owner's and the phone company's compartments, so moving it moves the provider's half too; the coax block, the fiber terminal and the drop clamp are the provider's outright. None of them is yours to move without the provider's say. Fiber is the hard case: the drop has a minimum bend radius, and a fiber kinked while a box hangs by it can break inside an undamaged jacket.

Painters. Paint over a box locks its latch and hides its labels, and a provider's tech may cut the box free and replace it. Paint over the bonding wire or the ground block's screws does not look like much, but it hides corrosion and a loose connection. Mask the boxes and the bonding wire, paint around them, and leave the box surfaces as they were.

Pressure washers. A high-pressure stream drives water past the gaskets of a NID or fiber box, and wet phone terminals produce noise, dead lines and corrosion weeks later. A narrow tip can cut the jacket of a drop or the coax. Labels peel off.

Everyone with a ladder. The aerial drop runs from the pole to a clamp on the house, often across the path to the gutter, the gable or a second-story window. It is not a power line, but it is easy to snag, and pulling it can tear the clamp out of the wall or pull the line out of the box.

What not to do

• Do not open the telco side of a NID, the fiber terminal, or any box with a provider seal or a special screw.
• Do not look into the end of a fiber or into an open fiber connector. The light is often invisible and can damage your eye.
• Do not cut, unscrew or leave disconnected a bonding wire. If one comes loose during your work, say so before you leave and get the right party to reconnect it.
• Do not remove a box because it looks abandoned. A dead-looking phone box may still carry the bond for the coax beside it, and only the provider can say a line is retired.
• Do not assume a phone line is harmless. An idle copper phone line carries about 48 volts DC and a ringing one about 90 volts AC, enough to hurt someone with wet hands. Many homes no longer have live copper service; you cannot tell by looking.

For the inside wiring these boxes feed, see related: Low-Voltage Wiring Basics for Non-Electricians.

Worked example: a repaint with pressure washing on the service wall

A painting crew is booked to pressure wash and repaint a two-story house. The service wall has, from left to right: an old phone NID at 3 feet off the ground, a coax ground block in a small box at 4 feet, and a fiber terminal at 4-1/2 feet, with the fiber continuing through the wall. A bonding wire runs from the NID and one from the coax block to a bonding bar beside the electric meter. The aerial drop arrives at a clamp 12 feet up, below the second-story window the crew needs to paint.

Before washing. The lead photographs each box with its labels readable and the bonding wires intact. He sets a working rule for the service wall: no pressure tip closer than 3 feet to any box, drop or bonding wire, a wide fan tip on that wall, and the area within 3 feet of each box rinsed with a garden hose instead. That is a common starting point; the wider the tip and the farther away, the less water gets forced past a gasket.

The drop. The second-story window trim sits 3 feet above the drop clamp. The crew plans the ladder placement so the ladder rails sit to one side of the drop's path to the pole rather than leaning across it, and carries the extension pole up from the side away from the drop.

Painting. The crew masks all three boxes and both bonding wires with tape and paper, cuts in around them, and removes the masking the same day so tape does not bake on.

A finding. While masking, the lead notices the bonding wire from the coax block is already disconnected at the bonding bar, its end green with corrosion, probably from years ago. His crew did not do it, but it is now in his photos. He tells the homeowner that the cable company should reconnect it and that it is a safety item, and notes the time he told them.

The tally. Three boxes, two bonding wires, one drop. Three boxes untouched by pressure and paint, one bonding wire intact as found, one bonding wire found already disconnected and reported, one drop worked around. Nothing was opened.

If the job had been siding instead. The same wall needs the three boxes detached. The crew calls each provider before the start date to arrange having the box and drop moved for siding work, asks the phone company the same question about the old NID even if the homeowner believes it is dead, and leaves every box on the wall until its provider moves it or says in writing that the crew may.

What changes the answer

Buried drops. A drop that arrives underground runs in a shallow trench or conduit to the wall. It is part of what a locate request covers up to the box. See related: The Utility Locate: Before You Dig.

Multi-unit buildings. Instead of single boxes there may be a larger terminal cabinet serving several units. Treat the whole cabinet as the provider's.

Satellite dishes and antennas. These have their own ground block and bonding wire, usually near the dish cable entry, and the same don't-cut, don't-disconnect rule.

How to verify you got this right

• End-of-day photos show every box, label and bonding wire in the same state as the morning photos, or the difference is written down and the customer told.
• No provider seal or special screw was disturbed.
• The drop is at the same clamp, with no new slack or strain.
• Any finding is reported in the words the provider will use: "the coax bond wire is disconnected at the bonding bar," not "a wire is loose." See related: Describing a Problem in Another Trade's Own Words.

References

• NEC (NFPA 70), 2023 edition, Section 250.94 and Chapter 8 communications bonding requirements, as adopted by your jurisdiction.
• Federal wireline demarcation rules (47 CFR Part 68) for where the phone company's responsibility ends.
• See related: Low-Voltage Wiring Basics for Non-Electricians
• See related: The Five Questions to Ask About a System That Is Not Yours