Can I Substitute My Thermostat Wire For Cat 5, Cat5E, Or Cat6?
Category ethernet cables like Cat5, Cat5e, and Cat6 are abundant in many households, prompting enthusiasts to look for additional ways to use them aside from Ethernet networks. This is especially true for Cat5 and Cat5e, which are now often being retired in favor of newer cables.
One of the common suggestions is to use Cat cables in place of a thermostat wire in a thermostat. The logic behind that is that both are low-voltage, low-current wires. But is this a good idea after all? Let's find out.
Is It Possible To Use Cat 5, Cat5E, Or Cat6 In A Thermostat? An Issue With Voltage Drop
Technically, it is possible to use Cat 5, Cat5E, and Cat6 cable in a thermostat, as both ethernet and thermostat wires are low-voltage wires. It does make any difference which one of the three you choose. However, one issue this application runs into is the problem of different gauges. A standard category cable is 24 AWG, while a thermostat wire is 18 AWG. Using a lighter wire in a thermostat may result in a voltage drop that is too significant for effective use. This is not an issue for a very short cable run, but it is a problem for a standard or long cable run.
This means that Cat 5 and Cat5e cables can be used in outdoor and remote thermostat sensors, but it is not practical to use them in control loads.
In a DIY installation, you may reduce the gauge difference issue by keeping the wires' ends twisted. Moreover, two 24 AWG wires laid parallel are essentially an analog of an 18 AWG wire. However, any DIY installation is run at your own risk.
If a thermostat cable is intended to run in the air-circulation spaces in buildings, it has to be plenum-rated. Not all thermostat wire is plenum-rated, but the one that is meant for in-wall applications is. Never replace plenum-rated thermostat wire with non-plenum-rated Ethernet cables. Choose only plenum-rated Cat 5, Cat5E, and Cat6 for such applications. Otherwise, you run the risk of fire and electrical hazards.!
If used, Cat cables are only suitable for low-voltage 24V-30V thermostats. They can never be used in 120v line-voltage thermostats as they are not rated for such voltage.
Arguments In Favor Of Using Cat5/ Cat5e Cables In A Thermostat
- Cat 5, Cat 5e, and Cat 6 cables are frequently cheaper than a thermostat wire.
- Many households have extra Cat cables in their households that have since been replaced by newer cables, making them free to use
- Cat 5, Cat 5e, and Cat 6 are better at preventing electromagnetic interference compared to the thermostat wire.
- Cat 5, Cat 5e, and Cat 6 will work in a thermostat most of the time as long as DIY is competent and thoughtful, and the run is not really long, 20' approximately.
Arguments Against Using Cat5/ Cat5e Cables In A Thermostat
- Cat 5/5e/6 is smaller at 24 AWG than an 18 AWG thermostat wire, which results in a voltage drop.
- Thermostat wiring has a generally recognized color-coding system that is necessary for the quality maintenance of the thermostat. Naturally, ethernet cabling does not follow the same color-coding standards as thermostat wire, leading to additional confusion when maintaining your thermostat. This will also create confusion for consecutive residents of your house, will there be any.
- According to NEC, CL1 and CL2 are the only approved methods of wiring a thermostat.
- There is an abundance of thermostat wire on the market, and all of it is cheap. Therefore, it is almost impossible not to access high-quality thermostat wire.
Conclusion
Technically, it is possible to use Cat 5, Cat5E, Or Cat6 cable in your thermostat as long as the most common safety concerns are met. However, we will not advise in favor of it, as there are many concerns related to this practice, while the actual thermostat wire is safe and freely available on the market. A wish to recycle your Ethernet wiring is the only reason to put CAT cables in your thermostat, and it is not always worth it.
To best match your thermostat at excellent prices, shop thermostat wire at Nassau National Cable.
