Top 2 Things to Consider When Running Ethernet and Power Cable
Written by Don Schultz, Technical Sales Representative and Fluke Networks Certified Technician
Have you ever wondered the effects of running Ethernet cable next to power cable? How do you make your install safe? And how do you avoid data loss? The answer is more complex than simple measurement of distance. There are two easy things to consider in order to ensure the safety and integrity of your network. First up is…
- Ethernet data cabling is classified as low voltage. Any type of AC wiring is classified as high voltage--even 120V AC.
- When running unshielded data cable parallel to typical residential voltage power cables (120V or 240V AC for example), the NEC (National Electric Code) specifies it must be separated by at least 200mm or 8 inches.
- The NEC further specifies that shielded data cabling may be run in parallel with lower voltage residential power cable if a distance of 50mm or 2 inches is observed.
- You may cross electrical cable with Ethernet cable at right angles as much as you like.
It should be noted that this is to meet national U.S. building code. Most municipalities adopted this code without change. However, there are municipalities that have their own rules. It’s the installers responsibility to research this. Typically you won’t see a difference in your area, however.
The NEC is concerned with voltage induction. Voltage induction means voltage can actually transfer from one cable to another due to the magnetic field generated by the higher voltage cable. In the case of Ethernet data cabling, this would not be good. The effect would be a piece of sensitive electronic equipment receiving voltage when it should not, potentially cause a fire hazard or voltage strong enough to cause personal injury or even death.
Voltage induction takes on a whole new meaning when extremely high voltage cabling like 480V is involved. DO NOT, under any circumstances, run Ethernet data cabling in parallel to extremely high voltage cable unless the…
- Power cabling is properly grounded.
- Ethernet data cable is shielded and properly grounded at one end only.
- Power cable or Ethernet data cable (or both) is run through separate metal conduit.
- Conduit(s) are properly electrically grounded.
- Cables are separated by a distance of at least 8 inches, even if both are running in their own separate metal conduits.
If you are using unshielded (U/UTP) Ethernet cable in proximity to extremely, high-voltage electrical wire, then start increasing the separation distances to feet instead. A good number to start with would be four feet, or 48 inches. I say start, because although the power cabling may be 480V, the amount of amperage being pushed across the cable may require increasing that distance even further.
The problem is there are only basic guidelines from the NEC to go by. This has led to anecdotal evidence from some (well meaning) individuals that say running Ethernet cables in parallel to electrical at closer distances causes no harm. In their case it likely did not, because the electrical wire was not being pushed to its amperage limit. So, in their particular situation at the time they stated this anecdotal evidence, this has become fact and they repeat it as such.
The fact is, the amount of amperage that an electrical wire passes will vary depending on what you have plugged into it, and when you are using the plugged in device. The same can be said for Ethernet cable as well...the amount of data passing through the cable is not constant.
In addition to meeting code, the separation distances are geared towards electrical safety and not high-bandwidth data integrity. As Ethernet data cable has increasing demands placed on it, such as 5GBASE-T and 10GBASE-T, the NEC guidelines may not be adequate to protect from data loss despite the fact you won’t burn your house down.
For all practical purposes, if the Ethernet cable is not expected to exceed 1000BASE-T (1 Gigabit) speeds then the above safety guidelines can be considered the minimum for data integrity. This means the electromagnetic and radio frequency interference (EMI/RFI) will not be an issue for achieving data signaling free from packet loss. Fortunately, at this moment in time, the vast majority of home networks are no faster than 1 Gigabit.
For Ethernet that is expected to carry 2.5 Gigabit or higher speed running parallel to electrical, the following minimums and tips will give the best results for data integrity:
For common AC wiring, such as 120V or 240V:
- Keep unshielded Ethernet data cable at least 16 inches away from the power cabling and only cross at right angles.
- If using shielded and grounded Ethernet cable, the minimum distance is reduced to 4 inches, but still only cross at right angles.
- When using metallic conduit for the Ethernet cable, or if the AC wiring is already inside metallic conduit, you can use the 2” separation rule.
For extremely high voltage AC wiring, such as 480V and above:
- Keep the Ethernet data cable as far away as possible is the general rule of thumb!
- If proximity cannot be avoided, always use shielded Ethernet data cable and keep it 48 inches or more away from this kind of voltage. Run the Ethernet cable inside metallic conduit if feasible or have a steel barrier between the low and high voltage cables.
- All Ethernet data cable must be electrically grounded at one end.
I know this is a lot of different information to absorb, and what you should do depends on multiple factors. I think this calls for nice infographics!
Following the NEC safety regulations and these data integrity guidelines will allow for a cable installation that is not only safe, but less susceptible to data loss. Know your environment, take the correct precautions and consult a registered electrician.
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