Top 2 Things to Consider When Running Ethernet and Power Cable
Have you ever wondered about the effects of running Ethernet cable next to power cable? How about running your Ethernet cable next to discreet (individual) high interference items like generators or fluorescent light fixtures? How about running an Ethernet cable outside suspended in the air?
The top two things to consider when faced with this situation are:
- Data integrity
Be careful of anecdotal evidence or advice! Anecdotal evidence from some (well meaning) individuals say running Ethernet cables or coaxial cable in parallel to electrical at closer distances causes no harm. In their case it likely did not or it went unnoticed at first, 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 interference that an electrical wire or other source emits will vary depending on what you have plugged into it, and when you are using the plugged in device.
There are rules for residential and commercial installations that have actual legal consequences attached to violating them (and recorded in the law as local Codes). Violate Code at your peril. There is an old, but apt saying: “Safety codes were written on top of bodies and property damage”. Following Code not only protects you, but helps ensure your communications cable will work the way you intended it to. Fines, loss of license, civil litigation, and even criminal charges await those who don’t obey the rules. Codes alone, however, are not enough. Often there are additional best practices that should be followed per industry standards. On top of all that, the specific manufacturer may have additional guidelines. Yes, trueCABLE does have additional guidelines!
Why is the National Electric Code not enough? Ethernet cable is being called upon to carry higher speeds (such as those afforded by NBASE-T) where even lowly Cat5e Ethernet can be pushed to 2.5 Gb/s. This makes Ethernet more susceptible to EMI/RFI compared to the past when speeds were limited to 100 Mb/s or 1,000 Mb/s (1 G). Considering that the NEC guidelines were developed with safety in mind (but not necessarily data integrity and higher operating frequencies) the NEC guidelines alone are not enough to plan out your installation and avoid trouble.
The NEC/NFPA 70 should be considered “shall do” and the minimum requirement. trueCABLE also has best practices and recommendations that fall under “should do” that were collated taking into account:
- NEC/NFPA 70 guidelines
- BICSI recommendations
- The ANSI/TIA 568 set of standards
We will note the differences where appropriate. First up, we will start with the “shall do”.
National Electric Code (NEC) / National Fire Protection Act (NFPA) Guidelines
- The National Electric Code is a guideline, but is not technically law. When a local code is created then it becomes law in that jurisdiction.
- Your local municipality likely adopted the entire NEC into law with no changes, but there are jurisdictions that adopted the NEC into law with significant changes and stricter requirements
- It is YOUR responsibility to know if your jurisdiction has stricter code requirements. Always consult the AHJ (Authority Having Jurisdiction) if you are unsure. Often the AHJ is a local authority like a code inspector.
All references and information are sourced from the 2020 revision of the NEC/NFPA 70. It should be noted that previous versions of the NEC may differ from the latest and when seeking information you should be careful that you are consulting the most recent version.
What does the 202 NEC/NFPA 70 have to say about communications cabling in proximity to electrical circuits? Well, it all depends on whether we are talking about indoor or outdoors. Take note that when we say “communications” circuits we are referring to any type of low voltage communications cable such as Ethernet, coaxial, and the like.
Outdoor Aerial Cable Guidelines - 800.44(A) through (D)
Section 800.44 addresses power cable or electric lights attached to the same pole for support as communications cable wiring or when power conductors are run in parallel to communications cable in-span.
- Where possible and practical, communications cable shall be attached below the power cables or lighting
- Communication cables shall not be attached to the same cross-arm that carries power cabling or lighting
- Supply service drops from the power company (up to 750V) running above and parallel to communications cable shall always be separated by a minimum of 12 inches and this includes the attachment point at the destination building. In addition, a minimum separation of 40 inches must be maintained at the attachment point of the service power pole itself.¹
- All communications cable must remain a minimum of 8 feet above roofs they pass over. There are two exceptions to this:
- This does not apply to auxiliary structures like detached garages
- If the communications cable does not pass over the roof more than four feet and if the communications cable is terminated at the roof, you may get as close as 18 inches above the roof overhang. Note: The implication here is that your attachment point cannot be shorter than 18 inches if it is attached above the roof.
- You shall not attach communications cable to the same roof mast as you attached the service (feeder) circuit power cable
¹ trueCABLE recommends a 24 inches separation minimum (on parallel) at any point during the span and at the attachment point on the structure when using unshielded Ethernet or dual shield coaxial cable. This may be reduced to 18 inches when using properly bonded and grounded shielded Ethernet cable or quad shield coaxial cable. At the service power pole, trueCABLE recommends a minimum separation of 60 inches when using unshielded Ethernet cable or dual shield coaxial cable. If using properly bonded and grounded shielded Ethernet cable or quad shield coaxial cable then the minimum separation should be 48 icnhes. Please reference the chart below titled “General Guidelines for Safety and Communications Cable Data Integrity”.
Indoor Guidelines - 805.133(A)
Section 805.133(A) addresses communications cables entirely run inside or running from inside and then attached to the outside of the same structure that might encounter electrical interference sources.
Note: Pathway means conduit, raceway, J-hook, cable tray, ladder rack, enclosure, etc. Also note that this section applies to 240V or lower electrical wiring. It does NOT address 480V or higher electrical wiring such as found in factories and commercial buildings.
- You may run various types of communications cable inside the same pathway without issues. So coaxial cable, Ethernet cable, and even low voltage fire alarm cable require no separation. For the electricians among you, that means Class 2 and Class 3 circuits can be run together.
- NEVER run communications cable in the same pathway as 120V or higher electrical wiring unless the pathway has a listed divider or permanent barrier to keep them separate. In electrician-speak that means no Class 1, power, electric light, or non-power limited fire alarm cables in the same pathway as Class 2 or Class 3 low voltage cables unless a listed divider or barrier is installed.
- In situations where a dedicated pathway is not used (like inside wall cavities), a minimum separation of 2 inches on parallel must be maintained from Class 1, power, electric light, or non-power limited fire alarm circuits when using unshielded communications cable. This requirement does not apply when the communications cable is shielded or if the communications cable is permanently separated from Class 1, lighting, or electrical cable by using firmly fixed rigid non-conductive conduit such as PVC or flexible tubing.²
- You may run low voltage communications cable over AC wiring at a 90 degree angle without restriction, but you should not allow the wires to physically touch. This is known as “crossing at right angles''.
² trueCABLE recommends an 8 inches separation minimum (when in parallel with electrical wiring) when using unshielded Ethernet or dual shield coaxial cable. This may be reduced to 2 inches in the same wall cavity when using properly bonded and grounded shielded Ethernet cable or quad shield coaxial cable. trueCABLE recommends properly bonded to ground metallic conduit separating the circuits from each other when 2 inches cannot be maintained. As a best practice, the communications circuit should be in the next adjacent wall cavity from any electrical circuits. Please reference the chart below titled “General Guidelines for Safety and Communications Cable Data Integrity” for additional variations.
Other Problem Areas
Avoiding areas of high interference (EMI/RFI) is not just about keeping a separation from AC wiring. It may also involve EMI/RFI sources like:
- High voltage electrical panels
- Induction heaters
- Fluorescent light fixtures
- Electrical motors
- Medical equipment
- Factory machines/equipment
These sources of high interference generate a “bubble” of EMI/RFI around them. This EMI/RFI bubble is a “keep out” zone. The size of the keep out zone can be reduced by using shielded cable. Making use of properly bonded and grounded metallic conduit will reduce the zone size further. It is all relative!
Representation of EMI bubble around a induction motor
Some areas of extreme interference may require a site survey to determine the “KEEP OUT” zone. Always consult a qualified electrician or professional who specializes in this type of analysis if in doubt.
In the table presented below we address both common situations and extreme situations and how to mitigate them while protecting your data. This table was developed from several sources including the NEC, ANSI/TIA, BICSI, and trueCABLE testing. If any listed item conflicted on separation distance between one or more sources, the stricter distance limitation was used. No distinction is made between commercial or residential spaces, as the commercial space rules and recommendations were used.
General Guidelines for Safety and Communications Cable Data Integrity
*Frequency induction heating introduces other distance limitations such as induced by temperatures!
Best Practices When Dealing With RMI/EFI Sources
- Inside walls cavities, your best bet is to keep power and communications circuits separated by using the next adjacent wall cavity
- Shielded pathways (EMT metallic conduit for example) and especially distance are your friends!
- Always properly bond and ground shielded communications cable or the cable shield will not function, rendering the Ethernet or coaxial cable effectively unshielded
- When using metallic conduit it should be properly bonded and grounded as well
- Using shielded Ethernet or quad-shield coaxial cable inside of metallic pathways is the most effective way to reduce EMI/RFI in extreme environments, in conjunction with distance
- If you are a residential installer, your local codes may not even address communications and AC wiring separation issues for single and duplex dwellings. If this is the case, follow the above guidelines as if they were Code. Your local inspector will likely thank you!
Following the safety and data integrity guidelines will allow for a cable installation that is not only safer, but less susceptible to data loss. Know your environment, take the correct precautions and consult a registered electrician or EMI/RFI specialist.
With that said, HAPPY (and safe) NETWORKING!
trueCABLE presents the information on our website, including the “Cable Academy” blog and live chat support, as a service to our customers and other visitors to our website subject to our website terms and conditions. While the information on this website is about data networking and electrical issues, it is not professional advice and any reliance on such material is at your own risk.