ECN Forum
Posted By: renosteinke Designing for Power Outages - 01/22/16 11:05 PM
As I was setting up my generator this morning, one thing became apparent: I had no easy way to power my alarm, cameras, phone, and computers, short of putting the entire house on the generator.

So, I wonder .... is it a good idea to have a separate circuit, hopping from room to room, providing power to receptacles dedicated to these uses? One could even make this a circuit separate from the usual house wiring, powered only when the generator is in use. Power failure? Just move the plugs.

I almost think I have seen this arrangement in medical facilities- an "emergency" receptacle right next to the 'ordinary' receptacle.

I rather like this arrangement, as it makes the generator network completely separate from the utility-powered network ... no need for transfer switches, no chance of backfeed issues. While the NEC seems to assume transfer switching, I don't think a parallel network is forbidden.
Posted By: LarryC Re: Designing for Power Outages - 01/23/16 12:48 AM
For "down the road" applications, perhaps a dedicated small panel feeding all of the generator powered circuits could be installed. If you decide to install a transfer switch later, some of the wiring is already installed. You would just have to move other dedicated circuits later. It would allow you to run the 240 V output of the generator and give you more power available for the larger loads during an extended outage.
Posted By: HotLine1 Re: Designing for Power Outages - 01/23/16 02:45 AM
Reno:

An inlet, backfed cb, and an interlock kit gets the gen power into your panel. You have to select the branch cbs you want to power up, Works fine for me, and a lot of others, and it's legal.
Posted By: HotLine1 Re: Designing for Power Outages - 01/23/16 02:51 AM
Reno:

Yes, there are multiple sources in some medical facilities. The "emergency", red HG duplex, and matching plate are from the gen.

Posted By: gfretwell Re: Designing for Power Outages - 01/23/16 07:42 AM
I have a back feed inlet and an interlock kit here. I am really not that prepared tho. I do have a good panel directory but I have not really gone through and mapped the breakers I would want to have on and the normal load on them. Best case would actually be a load rating on each "emergency" breaker and a list of which will work with the others.
Posted By: renosteinke Re: Designing for Power Outages - 01/23/16 03:09 PM
Does anyone see a need for surge suppression on generator-fed circuits? Just how reliable is their voltage regulation (especially as your load varies)?
Posted By: gfretwell Re: Designing for Power Outages - 01/23/16 06:43 PM
I doubt surge protection would buy you much on a typical portable generator. Your biggest problem is usually sags.

If I ever do decide to test my setup and I think of it, I will hook up my Dranitz and see what I have.
Posted By: Potseal Re: Designing for Power Outages - 01/23/16 11:47 PM
When the day comes to reno the basement I plan on installing a standby gen with an automatic transfer switch. How big of a standby gen I plan on using is the debate.


Reno, are you mostly concerned with surge suppression for ccts powering electronics? I think I would have a UPS ahead of the generator to deal with that concern.
Posted By: renosteinke Re: Designing for Power Outages - 01/24/16 02:32 AM
Potseal, as I see it, the joker in the sizing decision is the starting current required for motors. When your overall load is as small as mine - or when, in my case, all I'm powering right now is one motor - that starting current matters.

Now, my generator, even when bought at a bargain price, cost me more than many similar capacity generators that I see in some retail outlets? Why pay more? Well, the biggest differences are in the noise made and the reliability of the voltage regulation.

There's my concern about voltage spikes: the voltage regulation of the generator as loads change. I would hate for a high-voltage spike when the furnace motor stops to cause harm to any electronics that might be on line.

Yes, a UPS would help; I had forgotten about that. That might be a solution.

Greg, I'd love to see what actual measurements show.
Posted By: gfretwell Re: Designing for Power Outages - 01/24/16 07:10 AM
These days electronics are really not what I worry about. They usually have switch mode power supplies that tolerate anything from 100v to 250 or so. It makes them easier to sell around the planet.
Posted By: ghost307 Re: Designing for Power Outages - 01/25/16 03:50 PM
I bought a small UPS that I have the computer plugged into.
Isolating the computer from gremlins on the line is one of its benefits.
Posted By: gfretwell Re: Designing for Power Outages - 01/26/16 02:18 AM
Most cheap UPS units run in "bypass" mode when utility power is present so the isolation is not as good as you would think.
PCs are pretty much immune to most power line problems anyway. It is the other stuff you plug in that kills them, usually the phone line. We also had problems with LAN cables but they were running between buildings.
© ECN Electrical Forums