Test Station Assemblies

We put a lot of money into protecting our pipes. How do we know the coatings, joint bonds, flange isolation kits, anodes, etc., are all doing their jobs? We test these things. There's this magic number (-0.85 volt) in cathodic protection, that when epoxy, anodes, and the moon align, we should achieve perfect harmony for the pipes, and they will go on to live happily ever after. Periodically along a pipe, the pipe's owner will typically (required: gas, option: water, sewer) require test station boxes to help them determine if they are meeting that value. Too low, and the pipes are sick. Too high, and you could be damaging the coating.

A big part of what I do is look at drawings to determine the test station. There are variables (above-ground, below-ground, for instance), but typically it requires:

• A box with terminals (posts for attaching wires)
• Wires (running between the box and the pipe)
• Welding (a method of connecting the wires to the pipe)
• And a protective coating for the weld.

The box can be above-ground (mounted on a post) or flush-mounted (even with the ground). Denver Water in particular likes to use the Testox 917, a metal post-mounted option that is expandable from 1-10 terminals. Denver Water typically supplies the post for the 917, otherwise you would need: galvanized conduit, conduit straps, and a sturdy chunk of wood. Another option for a post-mounted test station is a polycarbonate nearly-indestructible plastic version that is actually pretty common, the red photo below by Tinker & Rasor. They come brightly colored, which means it is easy to identify a water line (blue) from a sewer line (purple) from a gas line (typically orange).

A lot of different wires feed into the test station. Typically there are 2 lead wires going between the test station and the pipe. Often in cathodic protection you will see twin sets of materials, as this is literally your pipe's insurance policy, and backups are essential. If the test station occurs where one pipe crosses another, you might have 2 sets (of 2) test leads, one in color A and another in color B so you can easily tell if both pipes are doing well. Other wires that might feed into the test station include: anode lead wires (which would utilize the previously-mentioned shunt), permanent reference electrode wires, or test leads that are on opposite sides of an isolated flange. Test stations can also be modified to act as coupon test stations, but that is a concept that requires additional research on my part and will be touched on later.

A good item to consider for the test station includes ring tongue compression lugs. These are part metal sleeve that encase the end of one wire, and a metal ring that loops onto the terminal (typically 1/4" diameter post in the test station), which eases removal for testing and etc.

The test station lead wires are welded onto the pipe, an exothermic process that includes PPE and explosions (aka: fun!). Up next!