What Voltage Does Ethernet Use in Office and Commercial Cabling Projects?

When a business calls for ethernet cable installation services, the first questions are usually about speed: “Do we need Cat6 or Cat6A?” “Will this support our Wi‑Fi?” “Can it handle cameras?”

Then someone asks a smart question that doesn’t get talked about enough:

“What voltage runs through Ethernet cables?”

If you’re wiring an office, warehouse, retail space, clinic, school, or any commercial building, understanding Ethernet voltage is part of building a network that’s reliable and safe—especially once you add Power over Ethernet (PoE).

This guide explains the real answer (without turning it into an engineering lecture) and shares practical things experienced network cabling installers look for during structured cabling installation services.

Quick answer: data-only Ethernet vs. PoE

·         Data-only Ethernet: Uses low-voltage differential signals designed for communication—not for powering equipment.

·         PoE (Power over Ethernet): Typically uses a nominal 48V DC system (within IEEE-defined ranges) so the same cable can carry data + power.

So yes—Ethernet can carry power. But it depends on your equipment and design.

What “voltage” means in Ethernet (in plain English)

Ethernet has electrical signalling on the cable so devices can “talk.” For standard data connections, those signals are low and controlled by the network hardware.

PoE changes the conversation because the network is now powering devices. That’s where voltage and wattage become real planning items—especially if you’re installing dozens of endpoints.

Here’s the practical difference:

·         Data-only problems usually come from cable quality, termination quality, routing, or interference.

·         PoE problems usually come from power planning (standard mismatch, not enough PoE budget, voltage drop under load or overheated/poor terminations).

PoE voltage and standards

Most PoE networks are built around a nominal 48V DC supply. The IEEE PoE standards define how much power is available to the device.

·         PoE (IEEE 802.3af): up to 15.4W at the source

·         PoE+ (IEEE 802.3at): up to 30W at the source

·         PoE++ / 802.3bt: up to 60W (Type 3) or 90W (Type 4) at the source

What this means for your project: if you’re powering modern Wi‑Fi access points, PTZ cameras, door controllers, or multi-sensor cameras, your switch and your cabling plan need to match the real power requirements. If you “wing it,” you can end up with devices that boot, then restart randomly—especially during peak usage.

The most common “it’s loading forever” and “it keeps rebooting” causes

In commercial environments, the goal isn’t just to make the network work today—it’s to make it stable enough that you don’t keep calling IT every week.

Here are issues experienced Low Voltage Wiring Contractors and network cabling installers watch for:

·         Rushed terminations (pairs untwisted too far, sloppy punch-downs, cheap RJ45 ends)

·         Messy cable pathways (cable laying on ceiling tiles, no J‑hooks/tray, sharp bends)

·         No labeling (adds hours to every future change)

·         PoE budget mistakes (switch wattage doesn’t match device count and device class)

·         Heat in bundles (high PoE loads + tight bundles can create real thermal issues over time)

Good, structured cabling installation services prevent most of these issues before they start. That’s why design + workmanship matters as much as cable category.

Do you need Cat6, Cat6A, or Fiber?

For many commercial installs, Cat6 is a solid baseline. Cat6A is often selected when the client wants more headroom (especially for future upgrades, higher-density environments, or longer copper runs).

But in practice, the “best” choice depends on the building and the network plan. If you have long distances, need high backbone throughput, or want better resistance to electrical noise, Fiber optic installation and repair is often the right approach for trunk lines between network closets.

A common, practical layout looks like this:

·         Fiber backbone between MDF/IDF closets

·         Copper drops (Cat6/Cat6A) to desks, APs, cameras, phones, and access control

Safety and compliance

Commercial low-voltage work involves more than drilling a hole and pulling cable. A professional team should address:

·         Pathway planning (J‑hooks, tray, and conduit installation where required)

·         Fire rating requirements (plenum vs. riser, depending on the space)

·         Proper separation from high-voltage lines where needed

·         Rack/patch panel organization

·         Labeling + documentation for every run

These details are exactly what separates “it works” from “it works and stays easy to maintain.”

Simple checklist before you request ethernet cable installation services

1.       Count devices: drops, cameras, access points, phones, door controllers, printers, POS, etc.

2.       Confirm PoE needs: which endpoints need PoE, and whether they require PoE, PoE+, or PoE++.

3.       Plan the PoE budget: total watts available on the switch matters.

4.       Choose the right backbone: copper only, Fiber + copper, or Fiber-heavy depending on distance and throughput.

5.       Ask for labeling + testing: it’s not “extra”—it’s what keeps support costs down.

FAQ

Is PoE safe in commercial buildings?

PoE is designed for low-voltage environments and is widely used in commercial settings. The biggest risks usually come from poor workmanship: bad terminations, low-quality components, crushed cable, or overheated connections. Professional installation practices keep PoE safe and stable.

Why do PoE cameras or access points randomly restart?

Most commonly: wrong PoE standard (af vs at vs bt), not enough total PoE budget, bad terminations, or cable issues that show up under load. A proper test and switch-port review usually finds the cause quickly.

Do I need shielded Ethernet cable?

Many offices do not. Shielding is typically considered in high-EMI environments (industrial equipment, heavy electrical noise). If shielded cable is used, grounding/bonding must be done correctly to be effective.

Get a free quote for your cabling project

If you’re looking for ethernet cable installation services, structured cabling installation services, Fiber optics, low-voltage wiring, or conduit work, the fastest way to get an accurate quote is simple: share your floor plan your device count, and your timeline.

Next step: Send your details through our form to request a free quote. We’ll recommend the right cable type, a clean drop layout, and a PoE plan that won’t fall apart once you add more devices.