[time-nuts] Line Voltage - USA

Bill Byrom time at radio.sent.com
Wed Jan 4 22:53:58 EST 2017

That sounds like a dangerous idea to me. Lightning arrestors at service
entrances are designed to crowbar only for a cycle or so. As mentioned
earlier in this thread, residential distribution in the US nearly always
consists of a center-tapped balanced feed with the center tap grounded.
If you placed a separate AC crowbar on each 120 V leg to neutral, the
first one to trip would momentarily create a higher than normal voltage
(transient and cycle-to-cycle) on the other 120V leg until the
distribution transformer opens (or a wire melts). If the crowbar wasn't
designed correctly you could create a house fire around the service
entrance. I would let the utility company and the National Electric Code
be the guide, as legally required.

You can purchase voltage regulators or line conditioners (the names are
not very precise) which can prevent overvoltage conditions on a circuit
or even the whole house. A UPS or active line conditioner can be used to
provide voltage stability on a cycle to cycle basis. There is no reason
to kill the power to you and your neighbors for what could be many hours
during very cold or hot conditions at night just because the line
voltage is temporarily high at your house. :)

Bill Byrom N5BB

On Wed, Jan 4, 2017, at 06:56 PM, Bill Hawkins wrote:

> Wonder if these cases could be used on social media to create enough

> fear that there would be a market for AC crowbars capable of blowing

> line/pole transformer HV fuses? There's a few hits with Google, mostly
> for DC crowbars. Too bad relays are so slow.


> Bill Hawkins

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