By Mike Yamane, Board of Directors

Utility poles host multiple services: electric, telephone and cable TV. Closest to the ground are the telephone and cable lines. Telephone lines generally have the thickest black cables attached to the utility pole. Cable TV lines are black insulated cable and are a little thinner than telephone lines.  

KIUC’s power lines are higher up on the pole. The power lines are made of an aluminum alloy and are grayish in color. The distribution lines are lower than the transmission lines, which are at the topmost section of the utility pole.  

Power lines do not touch the utility poles. They are attached to insulators, which are made of porcelain or rubber polymer, look like stacked plates and are attached to the crossarms or pole. The insulators prevent energized wires from contacting each other.  

There are two types of construction: one in which insulators are attached directly onto the pole, and the other in which insulators are attached to the crossarms. Crossarms are thick wooden beams bolted to the pole and braced diagonally. These crossarms usually have four wires affixed—one for each phase and a neutral.  

It is important to know that the higher on the pole you go, the more dangerous the wires become. The exposed power lines at the top carry the highest voltage.  

One way to tell if the line you are looking at is a transmission or distribution line is by the size of the insulator. The longer the insulator, the higher the voltage.  

Providing Power to the People  

KIUC maintains 1,400 miles of power lines attached to utility poles to provide power to our members. Overhead lines provide the most economical way of transmitting power throughout our community.  

KIUC’s transmission grid is comprised of approximately 171 miles of transmission lines that supply bulk power to substations throughout the island. Transmission lines operate at 60,000 volts and attach to large insulators on tall wooden poles or metal structures.  

Electrical energy from the transmission grid is converted at the substation to KIUC’s distribution voltage of 12,470 volts, or 12 kilovolts. The energy is then separated into multiple circuits, where it is routed to surrounding communities on distribution lines.  

At 12 kV, the voltage is still too high to go directly into your home, so distribution transformers—large canisters mounted on utility poles—step down the voltage again to the level required by your home: 120/240 volts. The 12 kV lines are called primary lines, and the 120/240V lines are called secondary lines.  

From the pole-mounted transformer, a secondary service wire—usually an insulated black wire—is connected to your home’s meter box. This allows KIUC to measure the amount of energy used.  

If you are in an area with underground wires, your transformer is in a green metal box mounted on the ground—usually next to a sidewalk. This is called a pad-mounted transformer. Make sure you heed all warning signs on these ground-mounted transformer boxes.  

From the meter box, service wires connect to the home’s breaker box, which functions as a safety mechanism for your home. It is at this point your home wiring enables energy to be sent to your outlets and switches at the touch of a button or the flip of a switch.  

Each utility pole has a tag. The pole tag is near the bottom of the pole and has a unique pole number. If you see a damaged pole or streetlight, take note of the pole number so you can provide that information when you report it. If there is no tag, take note of the nearest address and landmark to make identifying the pole easier for our crews. If you see a hanging wire, stay away and call our 24-hour line at 808.246.8200 to report it.