Generator hookup ideas - series or parallel?

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  #1  
Old 10-23-14, 06:55 PM
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Generator hookup ideas - series or parallel?

I currently have a 320 amp meter socket, with two 200 amp main panels running parallel to each other. I'm looking to back-feed my panels with a generator during emergencies. I have a 30 amp dryer hookup in my garage that I could put a twist lock on and run my generator just outside the door. I thought of doing this with a jumper wire between the two panels. During power outages the main breakers would go off and the breakers on both ends of the jumper wire, as well as the 30 amp dryer hookup, would go on. This would be putting the panel load centers in series with each other.

I had a friend mention the idea of running an 8 or 10 wire to both 30 amp breakers in each box, outside to a weather-proof box with the plug for the generator. This would wire them in parallel. It would also keep the generator feeder wire outside, and prevent having to have a door open or wire under the garage door in inclement weather, which sounds good.

Is series or parallel better for this application, or does it make no difference? I guess I should also mention that the grounds from each end of the jumper wire would be grounded into the buss bar(s).

Thanks in advance for any thoughts/ideas.
 
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Old 10-23-14, 07:19 PM
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The first thing you need to know is that a transfer switch is needed to ensure that commercial power and generator power cannot be going into the panel at the same time.

The next thing you need to know is that your idea of back feeding the panels would require the use of a suicide cord.
 
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Old 10-23-14, 08:12 PM
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If you have to ask series or parallel you do not yet have the skill set to attempt this. You need to learn the basics first. The book Wiring Simplified available in the electric department of some stores or on line at places like Amazon is a good place to start.
 
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Old 10-24-14, 01:13 PM
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Thanks for your comments. As mentioned, I'm just looking for ideas right now. After more research, I really like the idea of an interlock kit, preventing the generator breaker and the main breaker from being on at the same time. Using a transfer switch isn't law here, and I like the potential of having more than 6 or 8 circuits powered.

I'm starting to think that an outside 30amp box would be better than using the dryer hookup, and running that "inlet" to both of my 200 amp panels, both of which would get an interlock kit.

If I go this route, using interlock kits for both panels, running 10-3 wire from both panels to the 30 amp outdoor weatherproof inlet, should all be fine? If one panel pulls, say, 20 amps, and the other panel pulls load of 10 amps, neither breaker in the panel boxes will flip, but the 30 amp breaker on my gen will. Am I overlooking anything?

Thanks.
 
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Old 10-24-14, 01:31 PM
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I'm starting to think that an outside 30amp box would be better than using the dryer hookup,
It isn't even an option so nothing to consider.
Using a transfer switch isn't law here,
But I'll bet not injuring or killing people is. Many electric company lineman have been killed are injured by unsafe connections.

For your needs with such a small generator your best solution may be to use a transfer panel and move the loads you are likely to use to that transfer panel.
 
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Old 10-24-14, 01:42 PM
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Additionally, I don't see where you will need more than 10 circuits during a power outage. It isn't party time, but time to hunker down until the storm passes. You will need a much larger generator, as Ray says, to justify more circuits. I run mine on 8 circuits, with a small 6500 watt Kubota off propane. You can do without certain things, like lighting a bathroom. I have gone in the dark with no problems
 
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Old 10-24-14, 01:56 PM
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I understand that the "best" option is a transfer switch, but what would be the problem with interlock kits on the panel main breakers? It would prevent this fatality that is apparently assumed that I will commit the first time I use my generator. My bigger question, and the one I was seeking advice/comment on, is wiring the panel breakers in parallel or series, and to make sure I wasn't missing anything on that front.

Of course I won't power my whole house during an emergency. I already have the select few breakers marked that will be on during the outage.

I appreciate your all's comments, but I'd rather get some feedback on my actual question at hand.
 
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Old 10-24-14, 02:06 PM
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The problem is you don't have a single panel. You have two panels connected together at the meter socket so power to both panels must be isolated by a single device. An interlock can't do that.
 
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Old 10-24-14, 02:22 PM
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"You have two panels connected together at the meter socket so power to both panels must be isolated by a single device. An interlock can't do that."

Could I have an interlock on one panel, then feed the other panel off of it, putting panel #2 in series, downstream, to panel #1?
 
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Old 10-24-14, 02:24 PM
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prevent this fatality that is apparently assumed that I will commit
Until you have had it happen to a good friend, you will never know. We aren't here to give blessings to a situation that is absolutely not fool proof. As Ray stated, two panels can't be successfully interlocked with one device. A switch gear is the only safe way to do this.
 
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Old 10-24-14, 03:01 PM
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chandler/ray:

I appreciate you guys' comments, sincerely. I understand that one interlock device will only take care of one panel, and the other still wouldn't be "fool proof." This was the thought process between running double wires to a male 30amp inlet, having both panels with interlocks.

Negating the obvious safety concern with panel #2, if I wire panel #1 with an interlock to the generator, wouldn't panel #2 just be acting like a sub-panel, restricted by 30 amps or whatever the remainder of power after panel #1 has load being drawn?

With having both panels with interlocks, it prevents back-feeding POCO, but is there a concern with running two 10-3 wires to a 30 amp box and effectively mating both blacks, both reds, both whites, and both grounds at the connection to the plug?
 
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Old 10-24-14, 03:03 PM
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Could I have an interlock on one panel, then feed the other panel off of
That would cut your available amperage more than one third and defeat the purpose of having two 200 amp panels on a 320 amp meter base. You would in effect have only a 200 amp service.
 
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Old 10-24-14, 03:07 PM
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Ray,

I'm not sure I follow you last post. It would only be acting as a sub-panel during emergencies. I would still have 320amps when the grid is back on. Of course, I would have a 30 amp breaker in each box that would stay off all the time except when I was using the generator, and then both 200 amp mains would be off.

What are you thoughts on running two new wires to the gen hookup and mating them at the inlet?
 
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Old 10-24-14, 09:29 PM
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First of all, you would never connect things in series, only parallel.

The easiest, but most expensive, would be to have a 400 ampere transfer switch with the two panels connected in parallel to the output of the switch. The generator would connect to one inlet with the other inlet connected to the utility meter.

The least cost option would be to have all the circuits you want to energize with the generator in the same panel and then you could use an interlock provided it is acceptable to your local authority.
 
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Old 10-25-14, 12:26 AM
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It would only be acting as a sub-panel during emergencies.
Yes, so your total current available would be limited to the one main panel. That panel is 200 amps. The total amps used by both the main and the sub can not exceed the 200 amp limit of the main panel.
 
  #16  
Old 10-25-14, 05:38 AM
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Ray,

I would be limited to the 30A of my generator plug. This would allow 30A b/t both panels, correct?

Furd,

I agree that the best option for me might be to put all emergency circuits in one panel and wire that panel to the gen with a interlock; however, I'd still like to know if my idea(s) of wiring both panels would work, as far as methodology. I understand it's not foolproof as far as safety.

I've attached two pics of schematics showing the parallel and series ideas (I hope they're attached..first attempt at doing that).

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Size:  13.2 KBName:  20141024_215911.jpg
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  #17  
Old 10-25-14, 05:41 AM
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The last post put the same "parallel" idea picture on there twice. Here's the series idea picture...Name:  20141024_215924.jpg
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Old 10-25-14, 07:09 AM
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I really can't see your diagrams well enough to read the labels but either way requires two interlocks and as as has been stated that is not safe.
 
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Old 10-25-14, 07:24 AM
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One reason you can't use two interlocks is that you could theoretically leave one interlocked and the other one not.

Dedicating one panel to emergency use would be the direction to look towards.
 
  #20  
Old 10-25-14, 08:22 AM
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I appreciate everyone's huge safety concerns, but gee whiz, can a man get a straight answer to a question? I understand that there's this huge calamity about one not being able to remember to turn off both mains....I got it. With all the safety stuff aside, could I do one or either of my ideas, without any concern except for the safety aspect? I plan to proceed with one interlock and all emergency circuits in one panel, but for my curiosity and understanding of electricity, do you mind answering the question without considering the safety hoop-la?

Thanks.
 
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Old 10-25-14, 08:36 AM
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With all the safety stuff aside, could I do one or either of my ideas, without any concern except for the safety aspect? I plan to proceed with one interlock and all emergency circuits in one panel, but for my curiosity and understanding of electricity, do you mind answering the question without considering the safety hoop-la?
Name:  SC93.jpg
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Size:  2.4 KB Code must be followed. We will not advise you on how to do anything that is unsafe. Suggest you call an electrician to do this work.

Academics is fine. That is why I suggested the book Wiring Simplfied. Also we are happy to answer basic electric questions but when those appear intended to circumvent safety then we have to wonder about what you intend to use the answer for.
 

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  #22  
Old 10-25-14, 10:56 AM
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I am in complete agreement with Ray. I refuse to "sprinkle holy water" on any ideas that are patently unsafe and most of the responders (as well as forum policy) are in agreement.

There ARE other Internet resources that will bless unsafe ideas but I would rather take the high road when it comes to safety and that is why I prefer this forum. Rest assured that IF something has a safety problem there WILL be someone that will make the mistake. The problem is that often times the person making the mistake is not the one that suffers the injury.

AND, it isn't just you. Many, many people read these forums and never join or ask questions. If even one of them were to try something that you view as only academic they could be responsible for someone losing their life.
 
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Old 10-27-14, 06:57 AM
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I'm going to close this - the questions have been answered.
 
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