Temporary power pole questions
user-7521340
| Posted in Mechanicals on
Hello All,
We are planning our overhead Temp power pole for construction.
How do I figure if “Conductors are 150v or less to ground”?
We are using:
100 amp meter, ringless, horned
Ground Wire #6 w/grounding rod
multi-plex conductors
Thank you for your help!
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Replies
If you measure the voltage between any phase (“hot”) conductor and ground (neutral, in this case), you’ll see something less than 150v in applicable services. The common 120/240v residential service is 240v between the two hots, and 120v between either of the two hots and ground (or neutral, they’re the same for this case), and would be considered “less than 150v to ground”.
The same would go for 120/208v three phase. If you had 277/480v three phase, then the voltage between any two phases is 480v, but the voltage from any of the three phases and ground will be 277v. This would be “above 150v” due to the 277v to ground, and would NOT meet the requirements.
The usual temporary power is 120/240v single phase residential power which is less than 150v TO GROUND so you should be ok.
What specific code issue are you worried about? If you need to know how high to keep the aerial cable, you want to be 17 feet above the highest roadway surface (usually stated as “17 feet from low point of the sag [in the cable span] to the crown of the road”). You’ll probably want to use GFCI breakers in the panel too, which is a requirement on construction power circuits.
Note that sometimes you can run your #6 solid copper wire down the side of the pole BEFORE INSTALLATION, and staple a spiral of the wire on the bottom of the pole to act as your ground instead of using a separate ground rod. This is how the utilities usually do it themselves.
Bill
A single phase service be less than 150 volts to ground. But you will use wires rated for 600 volts.
The requirements are very local. Every utility has its requirements.
Most electrical contractors keep a few temporary pole set in stock for rent for less than the parts will cost.
I think you should consider paying to have the electrical service installed as the utility workers will be very reluctant to connect a service installed by a homeowner because if you make a mistake it could explode in their face. Just have them set the panel and you can run the small wires.
Walta