Tech Tips: How To Test Snow Melting Mats and Slab Heating Cable
In this video, our tech lead Scott shows you how to test a snow melting or slab heating system with a mega-ohmmeter.
Whenever you order a snow melting or slab heating cable, you should always test it to make sure it's in good working condition. The way to test these mats and cable is to use an electronic megaohmmeter. Each mat and cable needs to be individually tested. The megaohmmeter tests the insulation between the electricity carrying wires to the ground wire.
Each cable and mat should be tested as shown before, during and after installation.
Hello. Whenever you order snow melt or slab heating cable, it is crucial to test each cable or mat to ensure that it is in good condition before it gets buried in the concrete. The last thing you want is to install a mat that has been damaged during shipping, only to discover that it doesn't work when you turn it on. To effectively test these mats, rolls, or cables, you will need a mega ohmmeter.
There are two types of mega ohmmeters available. The older hand-crank mega ohmmeter is not recommended for use anymore, so we will focus on the electronic mega ohmmeter instead. Each roll or cable that you incorporate into the system must be tested with this device. If you do not own a mega ohmmeter, you can rent one from Warmly or check with local electricians, as many of them have this equipment available.
A mega ohmmeter tests the insulation between one of the electricity-carrying wires inside the system and the ground. For example, in a 120-volt system, one wire is typically yellow and the other is black. If it were a 240-volt system, you would see a red wire instead of yellow. To conduct the test, you will check the yellow wire against the ground and then the black wire against the ground to ensure that the current-carrying wires are not making contact with the ground anywhere in the mat or cable.
To perform the test, attach the black clamp to the ground and set the mega ohmmeter to 500 volts. Then, take the yellow wire and connect it to the ground. When testing, you should see an infinite reading, which indicates that there is no contact between the current-carrying wire and the ground. If the reading shows "OL," it also signifies a good condition. After completing the test on the yellow wire, you will repeat the process with the black wire, ensuring that you do not touch the wires during this procedure, as it involves a dangerous amount of current.
Once again, you should expect to see an infinite reading, confirming that there is no continuity between the black conductor and ground throughout the mat or cable. Each mat or cable should be tested in this manner before, during, and after installation to ensure that nothing has compromised its integrity. If everything goes well during the hookup, your system will operate flawlessly. Thank you for watching.
