Generator Cord Sizing 100' Run: Stay With 10-Gauge?

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Been using a 10-gauge cord to connect my little 2kw gennie in the garden shed to the transfer switch in the garage.
No problems in maybe 20 hours total usage and the numbers look right per http://tinyurl.com/nvkyq32 , which says the voltage drop will be 2.5% at full load.
My understanding being that the voltage drop should be less than 5% at full load.
Now I am going to add a second 2kw and run them in parallel. (Honda EU2000i + EU2000i Companion). viz: http://tinyurl.com/pjwqxbp
In outage mode, the house cruises on 800-1200 watts so 95% of the second gennie's function will be redundant backup in case there's a problem with one unit during an outage.
But since I will have two.... why not? Then we could fire up both during mealtimes and accommodate a toaster or a coffee maker... or the kitchen's big microwave.
With the two units connected in parallel, the power cord interface changes from a regular 3-prong plug to a 30-amp L5-30 twist-lock plug.
Running the numbers (Copper wire, 10 AWG, 120v, AC single phase, single set of conductors, 100' distance, load current 30 Amps) into http://tinyurl.com/nvkyq32 , I get a voltage drop of 5.99 (4.99 percent).
Less than the 5% limit - and, real-world, not just .1% less because the two gennies will never be putting out a full 30 amps.
I'm thinking I can keep using the current 10-gauge cord by making up an adapter with a female 3-prong receptacle on one end and an L5-30 male plug on the other end.
That way, one cord does it whether I use one gennie or two; cord winding/storage remains merely inconvenient instead of becoming difficult; and I avoid shelling out $250-$300.
Anybody see a flaw in this reasoning?
--
Pete Cresswell

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Per (PeteCresswell):

Correction: Looking at a photo of the actual outlet on the Companion, I see it is labeled "26.6" amps..... so the voltage drop is 4.43% instead of 4.99%.
--
Pete Cresswell

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On Sunday, July 27, 2014 12:06:56 PM UTC-4, (PeteCresswell) wrote:

Maybe I'm wrong, but I don't think you can do 30 amps. You have two identical generators that together put out 4KW. I may be wrong, but I'm betting that a generator that's rated at 4KW can only do that 4KW with a balanced load, ie either 16A @ 240V or 16A on each leg supplying 120V. In either case it's not thg 32A that you're anticipating. To do that it would have to be supplying 32A at 120V all to one leg and I don't think it does that, is rated to do it etc. So, I think the voltage drop is actually half what you think it is. And even if it wasn't I'd still be OK with the 10g.
Another note, since it's likely to come up. You brought up running these two generators in parallel before and they can be used that way because they are inverter type and specifically designed to allow it. You couldn't do it with typical generators, so thought I'd point that out before you get 6 other replies telling you that you can't hook them up that way.
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I am also thinking that about 16 amps is the max that can be delivered by the generators if they are paralled for 4 kw total.
For generators in parallel, yes there are some inverter types that can be paralleled with out any problem.
I have two generators rated at 5 kw each that just have the generators and not inverters.. I have often wondered if they could be paralled for more power. I know how to place them in parallel safely but wonder if they will stay synced up for a long period of time. Where I worked we did that all the time with motor/generator sets. As it cost lots of money to shut down some equipment, we used motor/genertor sets to vary the speed of some motors. We had a bank of about 20 sets, and one spare set. We would run both in parallel for a short time and then switch one off.
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Per trader_4:

Per Ralph Mowery:

I am too clueless to explain how or why, but these things are specifically engineered to work together and deliver 4000 watts peak and 3200 continuous.
--
Pete Cresswell

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On Sunday, July 27, 2014 2:21:41 PM UTC-4, (PeteCresswell) wrote:

I was using your full 4KW number in the numbers in my reply, treating it just like one 4KW generator. By my analysis a 4KW generator can only supply 16 amps on any conductor. If you have only 240V loads, it delivers 16 amps. If you have balanced 120V loads it delivers a max of 16 amps, ie 120V @ 16 amps and 120V @ 16 amps. And if you try to do an unbalanced 120V greater than 16 amps, eg put 30 amps on just one 120V leg, I don't think it can deliver it. Essentially you're only using part of the generator winding at that point.
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wrote:

They are inverter generators so they can lock the phases together. The question is whether they can lockj them in a way to give you 2 120v circuits with 240 between the outside legs. If so you are going to cut your voltage drop in half ... but you will need a 4 wire cable.
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snipped-for-privacy@aol.com wrote:

With the proper equipment , virtually ANY generator can be paralleled with any other . Because generators don't always run at exactly 60Hz , the key is to link them when they are "in phase" with each other . Once linked , they will be locked in phase , and while one may take on more than half the load , they will stay synchronized . One thing to consider is "circulating current" between the generators , as wall as power factors . I was an electrician in the US Navy , and one of my jobs was to monitor and operate generator control boards . Lots of the details are hazy after 40-something years , but I do remember the basics . Here's a link to a wiki that explains it very well , including a method that only requires 3 120v light bulbs . https://en.wikipedia.org/wiki/Synchronization_%28alternating_current%29
--
Snag



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wrote:

As long as you are never drwing 30 amps from the generator the cord will be "adequate". If I was setting up fresh I would buy a heavier cord - but what you have will continue to do the job.
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On Sunday, July 27, 2014 3:17:32 PM UTC-4, snipped-for-privacy@snyder.on.ca wrote:

Again, I don't see how you could ever draw 30 amps from a 4KW generator on any one conductor. AFAIK, you can only do half of that.
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On Sun, 27 Jul 2014 13:01:27 -0400, "Ralph Mowery"

That is EXACTLY what paralleled inverter generators do. They parallel synch and put out double the output of one generator into a single 120 volt line - unless they are connected "series synch" which gives you a 220/120 center tapped output which puts 15 amps max on each "leg".

They won't synch - period.

These "motor geerator sets" were "ward leonard" drives - AC motor running DC generator to run variable speed DC motors bu varying the field current of the DC generator. Parallelling DC generators is not a serious problem Parralleling AC generators is a lot of fun, unless one of them is a synchronous generator (like an overdriven induction motor)
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On Sunday, July 27, 2014 3:25:32 PM UTC-4, snipped-for-privacy@snyder.on.ca wrote:

I don't see why paralled generators would be paralled into just one 120V line. Seems more logical to just parallel both legs. If you can parallel one, why can't you parallel both legs? And regardless, it doesn't change what I posted about his voltage drop issue, ie the amperage on the conductors being 16A max, which is half of what he thinks it is.
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On Sunday, July 27, 2014 4:02:53 PM UTC-4, trader_4 wrote:

I just looked at the specs of the Honda EU200i which I think is the unit he actually has. It's strictly 120V, no 240V and it's rated at 13 amps continous. So there are not two legs involved like you;d have with a generator that's 240/120V and if you parallel two of them, you'd get 26 amps on the conductors.
So, I agree with Pete's analysis of the current and voltage drop. As I said, I'd be OK with it and use 10g cable. Especially if he already has it.
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wrote:

The inverters "link" - the pwm signal from the one inverter bank drives the other bank as well. It is more than just the outputs connected. In the one's I've seen the second unit (partner) is switched to the "partner" mode instead of the "stand-alone" mode and it picks up the synch signal from the output of the "master" to run the inverter on the "partner". Basically the "smarts " of the partner unit are shut off and it gets the timing signal from the master.
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On 07/27/2014 03:29 PM, snipped-for-privacy@snyder.on.ca wrote:

Would that make it single-phase 240 or two-phase 240?
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On 07/27/2014 02:59 PM, Rick wrote:
[snipp]

"two-phase 240" sounds like you'd get 480 across the whole thing.
These things are relative to ground, so it's a matter of what you do with the point that's between the generators.
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On Sun, 27 Jul 2014 14:31:39 -0400, snipped-for-privacy@aol.com wrote:

Some can work in both "series synch" (240 volt CT) and "parallel synch" 30 amp 120 volt mode.
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https://en.wikipedia.org/wiki/Synchronization_%28alternating_current%29
--
Snag



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The MG sets we were using were 3 phase 480 volt systems. We often used the light bulb or voltmeter system to put them in parallel. When the bulbs went out or the volt metes went to 0, then the switch was flipped. They then drove a bank of about 16 motors that were around 3 or 5 HP at 480 volt, 3 phase.
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wrote:

We don't even need to get that started again. It would be whatever one of the generators put out. Call it whatever you want.
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