[OPLINTECH] Planned power outage procedure

[Bob Neeper]

I tend to agree with Chad but add server's to the list.

And for what it's worth...

Keep in mind, most outlet boxes, surge protectors etc. use a single pole 
switch.
Only the Hot side of the line is disconnected. Ground and neutral pass 
right on through.

This makes a remote possibility of AC coming in on neutral or even the 
ground wire.

Sometimes neutrals can even come from a different transformer winding 
than the Hot lead.
More common in plants but possible in large buildings.

A neutral can always become disconnected (or loose) giving strange problems.
I had a rubber batching control system in Guangzhou with 30 or 40 
chattering relays as a result of a loose neutral.
Not good for them or the PLC's.     Definitely not good for a PC.
Luckily the Chinese tech had a screwdriver and plenty of time to tighten 
a hundred or so terminals.
We caught it before any equipment damage.

Everything depends on the electrician.

Really safe is, pull the plug and use a voltmeter (or some dongle) to 
test the circuit before plugging it back in.
Some surge protectors have wiring fault indication which should suffice.

Bob


R. W. (Bob) Neeper     Cell: (740)-407-3572 
Community Library
44 Burrer Dr.
Sunbury, Oh 43074
Tel:  (740)-965-3901



Chad Neeper wrote:
> If the device will auto-power on when commercial power returns 
> (copiers, refrigerator, etc.), then I might consider unplugging it. If 
> the device is plugged into a power strip, then I'd suggest simply 
> turning off the power strip. Particularly expensive or critical 
> devices (copiers, treasurer's workstation, director's workstation, 
> your workstation, etc.) you might consider unplugging as a precaution. 
> Weigh the rest against the staff time and inconvenience of unplugging 
> and then troubleshooting when the devices don't get plugged back in 
> correctly.
>
> In general, however, I wouldn't expect too many problems. Your 
> electrical service is probably sufficient to handle the sudden power 
> requirements of the handful of devices that will suddenly come alive 
> when the power returns. Also, when the power returns it will probably 
> be more like flipping on a light switch, rather than the sometimes 
> up-and-down that you see when the commercial power grid comes back 
> online.
>
> My 2 cents.
>
> (Are there any retired electricians or electrical engineers out there 
> that want to tell us if I'm on the right track here?)
>
> Chad
>
> -----------------------
> Chad Neeper
> Senior Systems Engineer
>
> Level 9 Networks
> 740-548-8070 (voice)
> 866-214-6607 (fax)
>
> --   Full LAN/WAN consulting services   --
> -- Specialized in libraries and schools --
>
>
>
> Phil Shirley wrote:
>> Our library is undergoing a renovation, so we've had small planned 
>> power outages on one or two circuits. When this has happened, in 
>> order to be completely safe, we've powered down the affected 
>> computers and unplugged   them from the power on the wall. With good 
>> surge protectors this doesn't seem necessary but it hasn't been a 
>> hardship.
>>
>> Some morning next week the power for the whole building is going to 
>> be out. We'll shut down the computers, but should we unplug them all 
>> from the wall?
>>
>> Phil
>>   
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