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Author Topic: Inverter Generator link kit question - Neutral overload?  (Read 1611 times)

drew gandy

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Inverter Generator link kit question - Neutral overload?
« on: August 13, 2020, 07:01:51 pm »

So I've been doing a little research on the multitude of 2000w range inverter generators on the market now. (Storm came across and wiped out power to a lot of homes a few days ago).

It seems that the link kits for these do NOT allow for 240v but instead for higher current at 120v. But, some of them appear to provide this power on 240V style connectors - apparently putting the same 'phase' on both hot terminals. These seem to be aimed at RV usage. But I'm having a hard time understanding how this won't lead to overloaded neutrals in systems where the neutrals are shared which is very common with 240v "split phase" power. 

What am I missing here? 

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Tim McCulloch

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Re: Inverter Generator link kit question - Neutral overload?
« Reply #1 on: August 13, 2020, 07:07:33 pm »

So I've been doing a little research on the multitude of 2000w range inverter generators on the market now. (Storm came across and wiped out power to a lot of homes a few days ago).

It seems that the link kits for these do NOT allow for 240v but instead for higher current at 120v. But, some of them appear to provide this power on 240V style connectors - apparently putting the same 'phase' on both hot terminals. These seem to be aimed at RV usage. But I'm having a hard time understanding how this won't lead to overloaded neutrals in systems where the neutrals are shared which is very common with 240v "split phase" power. 

What am I missing here?

I went through this with RV generators - if there are no 240V loads, the gensets have independent 120V windings with their own "neutrals".  The neutrals are jumpered together for output purposes.
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drew gandy

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Re: Inverter Generator link kit question - Neutral overload?
« Reply #2 on: August 14, 2020, 01:21:58 am »

I went through this with RV generators - if there are no 240V loads, the gensets have independent 120V windings with their own "neutrals".  The neutrals are jumpered together for output purposes.

Am I to assume that the RV is also wired such that all circuits have their own neutrals?
If so, I guess that covers RVs.
But NOT other systems that might use the same 240v plug expecting 180 phase between the two 'hots'.
More and more it seems clear that we should not share neutrals no matter how tempting it might be...
And that makes me wonder about using 6/5 wire with california plugs instead of 6/4 - Double up the neutral.
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Tim McCulloch

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Re: Inverter Generator link kit question - Neutral overload?
« Reply #3 on: August 14, 2020, 11:17:02 am »

 Neutral carries the imbalance of current, so in split phase systems the neutral current cannot exceed the circuit rating.
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Steven Cohen

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Re: Inverter Generator link kit question - Neutral overload?
« Reply #4 on: August 16, 2020, 05:39:22 pm »

The only 240 Volt inverter generator that I am aware of is the new Honda EU 7000. I think is also the first to use fuel injection.
The other inverters from Yamaha & Honda have a 30 amp, 120 volt connector. Which generator are you talking about?

So I've been doing a little research on the multitude of 2000w range inverter generators on the market now. (Storm came across and wiped out power to a lot of homes a few days ago).

It seems that the link kits for these do NOT allow for 240v but instead for higher current at 120v. But, some of them appear to provide this power on 240V style connectors - apparently putting the same 'phase' on both hot terminals. These seem to be aimed at RV usage. But I'm having a hard time understanding how this won't lead to overloaded neutrals in systems where the neutrals are shared which is very common with 240v "split phase" power. 

What am I missing here?
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drew gandy

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Re: Inverter Generator link kit question - Neutral overload?
« Reply #5 on: August 16, 2020, 06:06:39 pm »

The only 240 Volt inverter generator that I am aware of is the new Honda EU 7000. I think is also the first to use fuel injection.
The other inverters from Yamaha & Honda have a 30 amp, 120 volt connector. Which generator are you talking about?

I'm talking about 120v linkable inverter generators that provide their "combined" output on a 240v style plug. Take for instance this Energizer brand linking kit.



It's my understanding that in this kit, both of the "hots" in the 14-50R connector are wired to the same 120V (same phase). If we connect this to a power distribution system that shares neutrals for circuits that are 180 degrees out of phase with each other, aren't we risking an overloaded neutral? 
« Last Edit: August 16, 2020, 06:30:11 pm by drew gandy »
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Tim McCulloch

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Re: Inverter Generator link kit question - Neutral overload?
« Reply #6 on: August 16, 2020, 06:48:32 pm »

I'm talking about 120v linkable inverter generators that provide their "combined" output on a 240v style plug. Take for instance this Energizer brand linking kit.



It's my understanding that in this kit, both of the "hots" in the 14-50R connector are wired to the same 120V (same phase). If we connect this to a power distribution system that shares neutrals for circuits that are 180 degrees out of phase with each other, aren't we risking an overloaded neutral?

Great question.

Disclaimer:  Observations only, I've not opened up, used or laid hands on this device.

Each pig tail has 3 conductors, presumably line, neutral, ground.  The grounds and neutrals get bonded in the linking device.  But it's not a *circuit* between the 2 Lines, only the current from a line and its neutral are a circuit, so no, you can't overload an individual generator's neutral.  The neutrals are connected to a wiring device rated for the full load on each terminal.

The bigger question is there 240V from Line 1 to Line 2?  I'm thinking not, unless there's something else going on.  From the Home Despot description:
Quote
2 ports (120-Volt 50 Aamp 14-50R, 120-Volt 30 Amp L5-30R) are protected by rubber covers

It makes no mention of 240V so I think you're right.  From the pictures on the site it shows 2 dissimilar Energizer generators, this device, and couple of 5th wheel RVs in the background and that kind of reinforces my presumptions about this type of product.
« Last Edit: August 16, 2020, 06:52:07 pm by Tim McCulloch »
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Jonathan Johnson

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Re: Inverter Generator link kit question - Neutral overload?
« Reply #7 on: August 17, 2020, 06:36:22 pm »

Assumption: both "hots" on the NEMA 14-50R receptacle of the parallel kit are wired to the same "phase" which is where the "hots" of both generators are connected in parallel.

So here's what I see: each generator provides a maximum of 20A to the kit, for a total of 40A 120V, distributed across both hot legs of the NEMA 14-50R. One leg could see up to 40A, the other could see zero. That means that 40A will flow on the neutral. The neutral conductor of the RV cord is rated for 50A. In this scenario, even though it's fully imbalanced, the current on the neutral doesn't exceed capacity of the cordset, because the current on either hot is limited by the capacity of the generators -- a total of 40 amps.

Now, if you parallel two larger generators, capable of providing 30A (or more) at 120V each, then you could conceivably overload the neutral.
« Last Edit: August 17, 2020, 06:42:55 pm by Jonathan Johnson »
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Dave Garoutte

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Re: Inverter Generator link kit question - Neutral overload?
« Reply #8 on: August 17, 2020, 08:45:39 pm »

The only 240 Volt inverter generator that I am aware of is the new Honda EU 7000. I think is also the first to use fuel injection.
The other inverters from Yamaha & Honda have a 30 amp, 120 volt connector. Which generator are you talking about?
My Yammie EF6300 does 23A of 240v.
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Stephen Swaffer

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Re: Inverter Generator link kit question - Neutral overload?
« Reply #9 on: August 18, 2020, 12:22:57 pm »

Assumption: both "hots" on the NEMA 14-50R receptacle of the parallel kit are wired to the same "phase" which is where the "hots" of both generators are connected in parallel.

So here's what I see: each generator provides a maximum of 20A to the kit, for a total of 40A 120V, distributed across both hot legs of the NEMA 14-50R. One leg could see up to 40A, the other could see zero. That means that 40A will flow on the neutral. The neutral conductor of the RV cord is rated for 50A. In this scenario, even though it's fully imbalanced, the current on the neutral doesn't exceed capacity of the cordset, because the current on either hot is limited by the capacity of the generators -- a total of 40 amps.

Now, if you parallel two larger generators, capable of providing 30A (or more) at 120V each, then you could conceivably overload the neutral.

On that particular link kit, it says "circuit breaker protected".  It is not clear of both receptacles are protected-but I would hope so, in which case even larger gennys would be safe.
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Steve Swaffer

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Re: Inverter Generator link kit question - Neutral overload?
« Reply #9 on: August 18, 2020, 12:22:57 pm »


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