New National Electrical Code 2017 /2020 Requirements affect POE wiring.

Why Be Concerned About The Size Of Cables for ioT Devices?

Are you getting ready to wire up your new office or gathering quote for your next installation? Be sure to ask the question from your vendors what they are planning to do to meet the NEC 2020 Requirements for “power limited” cabling that would effect all POE installations.

Throughout the US, every state has adopted at least the 2017 NEC. However, despite this update in the code being over 9 years old, many if not most installation companies have either no knowledge of the code, or worst yet, they might be ignoring it, if enforcement is not consistent.

This update has to do with the Fire Code and has nothing to do with the speed of devices.

What is this new requirement and how does it affect POE installations?

To summaries what you are about to read, We suggest if you are going to use POE++ devices in the future then you should select a Cat 6A cable that has a Power Limited or “CMR-PL” rating printed on the cabling directly for the max wattage of your POE Devices.

POE devices receive power over the Ethernet cabling (POE). Depending on the the equipment this voltage is typically 48V. Until recently the wattage of these devices was rather small. An IP Phone for example might only be 5-10 watts.

However, starting in 2017 the NEC has realized that there are much more power hungry devices out there on the market. These devices are using 802.3bt protocol and consuming as much as 60-100 watts of POE Power. Some devices are POE powered switches which then in tern produce POE for its ports. There are POE powered drop in 2×2 and 2×4 light fixtures! (crazy right).

Think what this means. 100 watts of power on a Cat 5 cable that was installed in 1990! Wattage creates HEAT. Heat can relate to fire. Add to this, that POE used to only use 1 pair of the cable, so any little bit of heat it generated was not as much of an issue, but in Poe++ .bt the POE is using all 4 pairs of the cabling. That means the entire cable is heating up.

This increase in power and wattage means the cablings carrying this power will incredibly amounts of heat and will have a potential fire risk. This is particularly the case the larger your bundle of cables is in the ceilings, in your cable trays, and in the racks.

Nec 725.144 require cabling carrying the new POE++ devices to have a either a cable with a rating stamped on it that says “PL” (power limited) followed by its designed wattage, or you must prove to the inspector the wattage calculation of your devices, and the burn / melting temperature rating of your cabling. This is a combination of the fire rating of the cabling and the AWG (gauge) of the cable.

In addition, the chart in NEC limits how many cables can be in a single bundle when POE++ is in operation on the cable. For example, if you have a 25 or 26 AWG cat 5e cable, and it has POE++ running on it, the chart says it can only have 1-6 cables in a single bundle, because the wires are too small for this kind of wattage. Where as a cable with a 23 AWG and Shielded individual pairs, like a Cat6A or Cat 8 Cable, will have a much larger bundling ability. In most cases a standard Cat 6 23 AWG cable that was have been installing for last 2 decades, will only allow a 24 cable bundle by Electrical Code.

Making the wrong choice of cabling could cost you in the long run if it were to catch your building on fire, or if it simply prevented your construction project from passing the electrical inspection.

Charlotte Data Solutions has products that particularly have the LP Stamp on the jacket. Do we use this for every install? No. We customize your installation for what your current needs are.

Give us a call today to see how we can help you with your next Network Cabling Installation