What is a hot stick?
A Hot Stick is an insulated pole used by electric utility personnel when working on high-voltage electrical power lines to protect themselves from power arcs and electric shock. The Hot Stick electrically and physically insulates the worker from the power line, allowing workers to operate on energized power lines safely or when the status of the power line is unknown.
Hot Sticks are typically made from a foam filled, fiberglass reinforced plastic tube (FRP) which provides the required insulation, mechanical strength and a light weight. They can also be made from wood. Hot sticks are manufactured in a variety of set lengths or can be telescoping models, reaching lengths over 30 feet.
- ASTM Standard F 711 contains the technical characteristics for Hot Sticks made from fiberglass-reinforced plastic (FRP).
- OSHA Regulations 1910.269 and 1926.957 contain the testing and maintenance requirements for the Hot Sticks.
Each Hot Stick needs to be wiped clean before use each day to ensure that the surface of the Hot Stick has had all contaminants removed before use. It is important that the surface is clean and glossy. A glossy surface will cause water to bead-up, rather than wet-out the surface, reducing the chances for conductivity along the Hot Stick length.
The Hot Stick also needs to be visually inspected for defects that could undermine the insulative properties of the Hot Stick. Cuts and scratches found on Hot Sticks could allow moisture to enter the fiberglass and become electrically unsafe.
Special silicone-impregnated cloths can be used to provide texture for dirt removal and the application of silicone for water repellency.
The Hot Stick will need to be repaired and refinished or removed from service if any defect or contamination is found that would affect the insulating qualities or mechanical integrity of the Hot Stick. The Hot Stick will need to be examined and tested in a manner prescribed below before being returned to service.
Calibration and Testing Requirements
Per OSHA, Hot Sticks need to be removed from service for examination, cleaning, repair, calibration and testing every two years or anytime the daily maintenance inspection and cleaning finds defects that requires the Hot Stick to be removed from service.
Hot Sticks are constructed to withstand the following minimum tests:
- 100,000 volts per foot of length for 5 minutes if the tool is made of fiberglass-reinforced plastic (FRP)
- 75,000 volts per foot of length for 3 minutes if the tool is made of wood.
OSHA defines the testing of Hot Sticks in one of two ways:
- A Hi-Pot test that applies 75,000 volts per foot of length for 1 minute under wet conditions if the tool is made of fiberglass
- A Hi-Pot test that applies 50,000 volts per foot of length for 1 minute under dry conditions if the tool is made of wood.
The tests must verify the Hot Stick’s integrity along its entire working length. Wet tests are not to be performed on wood tools as they should never be intentionally exposed to water.
To pass the test, the leakage current within the foot-long section must not exceed 1 microamp per kilovolt of applied voltage. In the case of the Hi-Pot test, this means the leakage current can’t exceed 75 microamps per foot of a wet Hot Stick. In some cases, a failed section will arc and the test will severely damage the Hot Stick.
Some failed Hot Sticks can be refinished, which involves cleaning, buffing and waxing the surface until the item passes all applicable tests.