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[TowerTalk] generators/transfer switches etc Re: Yet AnotherLightning St

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Subject: [TowerTalk] generators/transfer switches etc Re: Yet AnotherLightning Strike
From: Jim Lux <>
Date: Sat, 08 Jul 2006 16:53:04 -0700
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At 03:43 PM 7/8/2006, Keith Dutson wrote:
>Slight correction.  This happened Wednesday, not Thursday.
>BTW, if anyone is wondering why I posted at this time while the IARU is in
>full swing, it's because I currently have a large thunderstorm parked over
>my QTH.  What would be a better time to think about lightning? <grin>
>There is one humorous thing I forgot to mention.  George recently installed
>a Generac emergency power generator that kicks in after 30 seconds of power
>outage.  The fireman switched off the main breaker before hosing down the
>roof.  30 seconds later the lights came on again.  So the fireman removed
>the meter from the outside.  The lights stayed on.  Then he found the
>transfer panel and turned it off.

This sort of thing (power staying on) scares the bejeebers out of 
firemen.  That's why there's a big red "Emergency OFF" switch at the door 
of a computer room with a UPS that shuts down all the power.

Take a look at Section 702 (I think) of the National Electrical Code. 
There's words like "The required signs must indicate the type and location 
of the on-site optional standby power source, and must be permanently 
installed and located at the service disconnection point and at the meter 
enclosure. "

That is, there should be a placard next to the meter that tells the fire 
guys and gals that pulling the meter isn't going to shut off the power. 
Even if the NEC doesn't require it, your local building code might.

Same sorts of things apply to solar panels and wind generators.  The former 
are a "real problem", because if the sun is shining, they're electrically 
hot.  The newer solar panel installations run the panels in series to get a 
bus voltage of several hundred volts (so you can directly make 120V/240V 
from them).  Just what the fireman wants as they chop a hole to ventilate 
your house.. a wire carrying 300V DC.

And just to throw in a "grounding" issue.. there's also some rules about 
interconnecting the grounding system of the generator and the rest of the 

If you're installing any sort of power source that's going to interconnect 
with the "standard house wiring" (i.e. not stringing extension cords), it 
behooves you to go check out the latest rules.

Many, many localities have also updated their rules in the last couple 
years because of the large number of generators purchased for Y2K, to 
respond to the increasing fragility of "the grid", and because of the 
outages due to natural disasters.  Just because Lowes or Home Depot sells 
it doesn't mean it's legal to install it. I haven't seen them recently, but 
a couple years ago, HD was selling transfer switch kits for use with 
generators that would be a real challenge to install in a code compliant or 
safe way.. presumably, somewhere in the world they were legal, but not in 
the U.S.



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