Hot sticks: Testing the tester reveals shocking results
|Journeyman Lineman Chad Rocco, from Montrose, Colorado, operates the hot-stick high-potential tester during an evaluation at Gila Substation in Arizona, April 28. Western crews tested the accuracy of three hot stick testers to see if they complied with Occupational Safety and Health Administration regulations. (Photo by Matt Monroe)|
by Lisa Meiman
America does not run on a certain famous donut, it runs on electricity (and maybe also the donut shop’s coffee).
To keep power flowing while repairing insulators, dampers and conductors, Western maintenance crews perform live-line maintenance, which means the lines and equipment are still energized, or “hot,” during work. The backbone of live-line maintenance, and the main tool protecting a lineman from a potentially fatal electric shock, is an insulated fiberglass tool known as a hot stick.
In April, maintenance foremen from around Western convened at Gila Substation near Yuma, Arizona, to test their hot sticks and also their hot-stick testers. “We are required by the Occupational Safety and Health Administration to do testing every two years on live-line tools,” said Headquarters-based Engineer Gary Zevenbergen. “The hot sticks can pick up dirt or other contaminants, which make it more conductive and less safe.”
Desert Southwest Aerial Observation Lineman Roger Harris added, “If your hot stick fails, you’re going to die.”
OSHA allows employers to test the hot sticks in one of two ways:
- High-potential, or high-pot, test applies 75,000 volts for one minute along each foot of a wet hot stick
- Other tests where the employer can demonstrate equivalency to the high-pot test
To pass, the leakage current within the foot-long section must not exceed 1 microamp per kilovolt of applied voltage. In the case of the high-pot test, this means the leakage current can’t exceed 75 microamps per foot of wet hot stick.
Each region uses a different tester for their hot sticks. Rocky Mountain uses the high-pot test while Upper Great Plains and Desert Southwest use portable testers, which test smaller sections of the hot-stick at a reduced voltage and require less time and people to operate. Sierra Nevada uses a downscaled high-pot tester that measures leakage current at only 10,000 volts. “The portable testers are supposed to be scaled to be equivalent to the high-pot test,” said Zevenbergen.
“We have been using the portable testers for years,” said DSW Line Crew Foreman III Mark Depoe. “Earlier this year, we had a crew from Montrose helping us out with a job, and they shared how they tested their hot sticks. We asked Gary Zevenbergen to assist so we could get a comparison and see if our portable testers were compliant.”
The portable testers were built by vendors who claim their equipment is OSHA compliant. “I took the approach that OSHA requires the employer to demonstrate that the test is equivalent, not the vendor. Unless we have documents on file that shows we got the same answers from the portable as the high-potential test, we haven’t proved they are equivalent,” said Zevenbergen.
At Gila, it was a high-pot tester from Montrose, Colorado, versus the two different portable testers from UGP and DSW. The group tested four hot sticks of varying lengths and condition using all three tests. “The results were eye opening,” said Montrose Journeyman Lineman Chad Rocco.
If a hot stick fails
Failed hot sticks are refinished, which is like washing a car. First, the crews remove the surface grime and other contaminants, buff out any dings and dents then wax the stick until water beads on the surface. Then the stick is tested again. If all sections pass, the stick is put into service. If not, then the stick is disposed.
Out of the 41 foot-long sections, 21 failed the high-pot test. In comparison, one portable tester only showed three sections that failed; the other only one. “In most cases, a stick with multiple sections in the red barely registered an issue on the portable tests,” said Zevenbergen. “It would have been one thing if they were both failing or passing the same sections. The leakage current doesn’t matter. The pass-fail standard matters. The portable testers weren’t even close.”
“I was a little disappointed in the test results,” said Harris. “The portables are faster and easier. Now we need to do a high-pot test, which takes more time and people.” The portables only need one person to work; the full high-pot test requires four.
When it comes to safety, you have to do what’s best,” said Depoe. “We’ll be using the high-pot test from now on.” SN also upgraded to the full high-pot test. UGP is doing a few more tests with Zevenbergen later this year
But it’s not all bad news. “Going through this experiment really helped the crews get familiar with how a good hot stick is supposed to feel, how it is supposed to look like,” said Zevenbergen. “During the testing, they started to identify which sticks were likely good and which were bad by look and feel even before we tested them. This will encourage the crews to take better care of their equipment. They’ll own that gear, take care of it, and rely on it.”
“The reality is it takes longer, but it’s a better test,” concluded Depoe. “You get results you can trust.”