Connecting Neutral & Ground from Generator to Home

RCinFLA said:

Read attached two pages from Powerhorse manual, highlighted text.

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WOW - very interesting! Not sure you caught I'm actually using the smaller 4500W Powerhorse(s) (p/n 83171). I wish the 83171 manual had instructions like this! I contacted Northerntool previously in absence of parallel connecting instructions (both the inverter and the parallel kit = nothing) - the verbal direction clearly was "start first, then connect". No pun, I was shocked and questioned him and he said all their training was just that...

Everything I hear (as you previously advised) and read consistently (other brand manuals) has been otherwise, connect first then start. Anyone has otherwise I'm all ears - I think I checked at least 4 other brands. I actually tested (start 1st, connect 2nd) and didn't like the way it sounded plugging in the 2nd unit (no load) and hearing both syncing. The 7500W unit makes it very clear though. I think I'm going to post something in their public forum for my p/n in question of connecting instructions to hopefully get the careful correct answer...

Thanks for that detail!

RCinFLA said:

There are many Youtube videos out there that say don't waste your money on an expensive parallel kits sold by manufacturer, just make a 'Y' suicide cord with two male plugs. Very irresponsible and unsafe but it does work. All the plastic shrouded banana plugs on a parallel cable kit go to the AC outlets in the inverter-generator. Many inverter-generator manuals have basic block schematics that show their connections.

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I'm with you on the killer cords - I've seen those too and wouldn't want to risk 2 brand new inverters! CRAZY

Thanks for unpacking the iceberg on how the inverter basics - your experience is more than a book I think...

Tecnodave said:

Exactly where did you discover this.......

In the ones that I have been into the generator is three phase AC variable frequency which is exactly what allows the generator to throttle up faster as more power is needed and reduce the throttle when less power is needed. This results in variable frequency at output of the generator, it varies from about 30 hz up to 400 hz, again three phase Then it is then rectified to DC. that is what appears ot the banana connectors......DC....The inverter in the generator takes this DC and inverts this into AC........The inverter in only one generator is used to provide the 60 hz. output

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I'm still trying to understand how to translate neutral through my circuit (Inverter <--> House).
I've searched and can't find any Inverter Parallel kits that use "four" banana wires, not to mention a NEMA 10-50R (very old school plug).

I think I'm hung up on the banana leads being DC - or do I have this wrong?
When connecting the banana leads to Inverter control panel, I get continuity between:
Red/Black banana lead to Inverter L14-30 plug Leg1/Leg2
Green banana lead and Inverter L14-30 plug ground
White banana lead and Inverter L14-30 Common

These are all for AC, right?

A picture to go with above: Model# DPC-004 (from the website).

I'm told by supplier product is modified sine wave. Therefore, I assume I have High Frequency Modified Sine Wave in my case.
How that translates to AC I'm not quite sure, but wonder if it works like traditional AC we have in US, using neutral in transformer to pull out the 120v? I am able to to 120V from L1 or L2 to ground in the NEMA 10-50R, so it's not only 240V with the parallel kit.

Here's a pic of the inverter board. The 2 wires at opposite corners (black/red) lead to the L1/L2 of the L14-30 plug.

I have seen an inverter-generator that is modified sinewave but it is an old rare relick. Pretty safe to say all inverter-generators are sinewave output.

The banana plugs are AC and just go to the AC outlet socket internal to the inverter generator. The color coding is to ensure you don't reverse the leads and get the two inverter-generators running 180 degs out of phase. With the power being taken from the actual banana lead connections reversing them does not even matter as the paralleling of the AC output will also get matching reversal.

It is a slight bit better to keep the two gens in phase per the parallel color code as a half cycle surge current spike will be applied in exactly same way on both generators inverter circuitry. For a 240 vac inverter-generator their are two 120v inverters operating in series. One of them is master and one is slave for phasing so it is preferable to have any surge spike phasing to be applied to master or slave side on each inverter.

Surge spikes can pertubate the phase synchronization so it is preferred to have any pertubation caused by surge spike to react the same way on both generators.

If it was me, and you cannot get the blue box apart to replace socket with NEMA 14-50, then I would cut the two banana lead cables at the blue box and build a new box with a CR6369 or NEMA 14-50 socket.

If you want a bandaid, use the L1, L2 hot line from the blue box NEMA 10-50. Make another two cords going to your service entrance CR6369 or NEMA 14-50 female cord plug. One of the two cores to the blue box NEMA 10-50 for L1,L2. Second cord only connecting white neutral and green ground wires on service entry CR6369 or NEMA 14-50 female plug going to a NEMA L14-30 male plug only having neutral & ground connections that you plug into either generator L14-30 outlet.

In the bandaid, an unplugged-in male NEMA L14-30 plug neutral could have voltage if you have 120v house loads plugged in.

I don't like the band-aid, and as I said I would cut the cords to blue box and make a NEMA 14-50 socketed replacemet box.

Other possibility is you can probably find a third party parallel kit cord or other brand parallel kit cord with a proper four wire 50A socket.

Thank you for ideas. Seems basic case of dammed if I do or don't.... Good news is the parallel kit was only $40.
With generators taking 5 months to fill order (Feb - June) I'm not sure what wait is - especially with import line currently sitting in Pacific....

Seems we're aligned that it's OK (or desired) for neutral to pass through to parallel kit/gensets - as when connected to L14-30 (parallel mode).
Wonder what purpose is though - not for syncing, and apparently not to split the 240 like when using grid transformer.

I just realized a check/test I didn't try that helps prove/test neutral function - measure parallel NEMA 10-50R L1/L2 to "house" neutral and ground.

Just realized I need to patch the ground through too, sine I don't plan to physically connect cords 1 & 2, but isolate this neutral test.
Thank you again !

NEMA 10-50R box opened (or is Pandora's box)

ePowerBank said:

NEMA 10-50R box opened (or is Pandora's box)

View attachment 66238

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As configured, parallel kit outlet is only good for 240vac loads.

Manufacturer saved a couples of pennies not putting in NEMA 14-50 in parallel kit box.

One possible warning. Some inverters-generators do not allow neutral to ground bonding. Many 120vac only inverter-generators state this in their manual, usually stated as 'do not connect generator to house wiring'. I would find it unlikely for a 120/240 vac generator but anything is possible with a cheap chinese inverter-generator.

Cord #2 plugged directly into NEMA L14-30 on generator implies this generator should be able to be neutral grounded. Cord #1 adaptor to parallel kit does not bring neutral to house service entry box from parallel kit box so not very useful as only 240vac devices would be powered.

Worse than just having 240vac, any 120vac loads will have floating neutral so the 120vac house outlets will have varying voltage depending on how much 120vac loads are on each side of L1, L2 to neutral. Very unsafe and hazardous to 120 vac appliances plugged in. Very bad design! Shows total lack of understanding of U.S. split phase system. So can you believe the cord #2 plugged into one generator L14-30 outlet to house service entry is correct ???

You should contact Northern Tool and tell them they should remove this parallel kit from their product line as it is a dangerous product. At least get your money back.

If single gen is capable of being neutral ground bonding then the paralleled generators should also be neutral-ground bondable.

RCinFLA said:

As configured, parallel kit outlet is only good for 240vac loads.

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Exactly what I've been wondering.
Does it mean anything, however, if there's 120v L1/L2 to Ground on the NEMA 10-50R when both genset are on?
Is that what would happen if one of these old plugs was in our house?

RCinFLA said:

One possible warning. Some inverters-generators do not allow neutral to ground bonding. Many 120vac only inverter-generators state this in their manual, usually stated as 'do not connect generator to house wiring'. I would find it unlikely for a 120/240 vac generator but anything is possible with a cheap chinese inverter-generator.

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Appreciate concern! I hope this (not for house backup) doesn't apply for me.
In my case I actually don't want bonding at gensets, but at MAIN panel.

As I understand, gensets that have bonding at gensets are sold towards portable use, or for case of a large unit that OSHA wants grounded, AKA, Separately Derived System. I don't have continuity between ground and neutral on my generators, therefore, I assume I have Floating Neutral.

Also, manual suggests home backup is an option:

ePowerBank said:

Exactly what I've been wondering.
Does it mean anything, however, if there's 120v L1/L2 to Ground on the NEMA 10-50R when both genset are on?
Is that what would happen if one of these old plugs was in our house?

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Only if neutral is grounded internal to generators. This would be a code violation with current flowing on ground wire of parallel kit box.

Voltage drop caused by 120vac loads across parallel kit cable would mean there can be some voltage difference between generator case ground and house grounding. Again, not a safe situation.

"Is that what would happen if one of these old plugs was in our house?"

NEMA 10-50 plugs are only used on some ranges, clothes driers, and maybe some window A/C's that only require 240vac.

RCinFLA said:

Worse than just having 240vac, any 120vac loads will have floating neutral so the 120vac house outlets will have varying voltage depending on how much 120vac loads are on each side of L1, L2 to neutral. Very unsafe and hazardous to 120 vac appliances plugged in. Very bad design! Shows total lack of understanding of U.S. split phase system. So can you believe the cord #2 plugged into one generator L14-30 outlet to house service entry is correct ???

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Understood, and a concern I tried to address by installing meters - below from a couple weeks back was at the 2 generator HOT legs entering MAIN. Does this cancel your concern (I HOPE) for varying voltage?

I think part of your comment is at heart of my issue (concern) - "how to apply Neutral in this case". I wonder if it's something similar to installing High Frequency Inverters? How 240v is split when coming into homes from a transformer isn't same, and maybe source of this problem? My mind is parked on idea that AC needs to return or cycle back to source (the generators or home panel?).

YES, the L14-30 at the generator control panel works (how below readout was connected - so maybe I stop there and full-load test (I was successful in partial load testing the micro and HVAC fan).

NO, I wasn't successful testing Cord #1 (NEMA 10-50) and fried 2 power strips.

Replace 10-50 with 14-50 socket.

Connect L1, L2, and ground as was with 10-50 socket.

Remove white neutral wire splice and connect them together on neutral of 14-50 socket.

RCinFLA said:

Replace 10-50 with 14-50 socket.

Connect L1, L2, and ground as was with 10-50 socket.

Remove white neutral wire splice and connect them together on neutral of 14-50 socket.

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I like that - what was suggested a long time ago, but I was too cheap to save the terrible $40 piece junk.

I know that the L14-30 works (in parallel mode), which includes a neutral.
I know the banana lead on generator control panel has continuity to generator neutral.

As you say, it seems I'm just upgrading the cheap (30A) plug for a 50A plug ;--(

Either I'm going to make a new box, or buy another parallel kit, that maybe includes a circuit breaker, or better yet, a breaker ON/OFF switch.
So much for the cheaper solution - you gets what yous pays for.

Well if at first you don't succeed, go to DIY Solar Power Forum for input you want to hear, and maybe even input you don't want to hear.

After plenty of research (and input) I came to conclusion the parallel kit sold with my generator was junk with old NEMA 10-50, so I replaced with NEMA 14-50.

Successfully tested my homemade parallel box with the new 14-50 today, ran microwave, sump pump as well as lights etc. Further load tests to follow, i.e. furnace etc.

Don't like the cheap volt / amp meters I went with and wouldn't recommend as the display is hardly visible. I tried putting copper tape on one but still bad.

THANKS ALL FOR YOUR CONTRIBUTIONS !

I like your solution, when I first saw that original wiring I stumped as to how that could possibly work, It is way not code to float the neutral, no way could that be legal as to the NEC, It was a compromise to use the non safe 10-50 connector that is used in an R.V.

Stoves and dryers used to be NEMA 10-50 connector and that is OK if all the loads are 240 volt only but most modern stoves and dryers use 120 volts for the controller and most electric stoves have a 120 volt outlet therefore are not 240 volt devices but are 120/240 volt split phase devices so the standard for newer appliances require the use of the NEMA 14-50 connector.

If my R.V. were 120/240 volt I would definutely change the cord and connector to the NEMA 14-50 connector.

In any and all instances the neutral and ground should be bonded at one place and one place only. In the situation of the R.V. connected to shore power that neutral bond belongs in the main power panel but when the R.V. is on its own making its AC power from the inverter or generator on the R.V. Some form of ground bond switching is required here. Most high quality Inverter/chargers meant for this use do indeed have a “ground bond switching relay” My MagnaSine does and the Samlex EVO also uses the ground bond relay so when you connect to shore power (charger mode) the inverter opens the neutral/ground bond locally but when in invert mode the neutral/ground bond is done by the inverter.

One problem poorly diagnosed is the EMI/RFI filter found on all switch mode devices which filter off the EMI/RFI from the hot and neutral conductors and shunt that current back through the ground wire. If there are unequal noise currents on the live wire and the neutral wire this will cause the GFCI to trip as the hot wire and the ground wire must be within 3 ma. of each other. The GFCI devices meter only the live and neutral wires, not the ground wire. So if there are 10 ma. of noise on the hot wire but not on the neutral the GFCI will see this as a ground fault and trip. I have seen freezers on a concrete floor in a garage where they could not be protected by a “personnel” GFCI which trips at 3 ma. The solution is to use an “appliance” GFCI which trips at 30 ma. These are not available as an outlet but are a dead front device (no outlet but input and output wires which are hard wired) which is wired in series with the outlet, It is the same form factor as a normal outlet so an “appliance” GFCI can be mounted in a double box with a NEMA 5-15 or 5-20 outlet to provide that protection. This is commonly done with hydronic zone heating systems to provide GFCI protection on the concrete floor that the furnace is mounted on. This would also be legal on a generator as it is an “appliance”

Tecnodave said:

My MagnaSine does and the Samlex EVO also uses the ground bond relay so when you connect to shore power (charger mode) the inverter opens the neutral/ground bond locally but when in invert mode the neutral/ground bond is done by the inverter.

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@Tecnodave Thank you for your reply - I'm guessing this is something many of us have in common (no joke lol).

Just curious, what type of application you have the MagnaSine in?

I have a small house out of town with very unreliable power company feed in the Santa Cruz mountains. Im totally set up as off grid but i do have a power feed from the power company, its not reliable and is 120 volt only 30 amps. I have two banks of flooded lead acid @426 a.h. each charged by two MidNite Classic 150 charge controllers so even in nasty weather I have enough power from solar alone. Due to government regulations the whole solar array is mounted on non buildings so the building inspector has no say. Im totally code compliant but the main is mounted on a large old motorhome, panels,controllers, the works. I run power to the house via a flexible cable so it’s not hard wired. Its not a building so the building department has no say anyway it is a state registered vehicle so the county has no say....

The whole system is bonded together with only one ground connection at the main panel of the house ground rods at the motorhome location bonded back to main ground rod at power company meter location.

My other is a cabin in Alaska out of town as well, 1,200 watts small inverter...real basic but a luxury in Alaska MidNite charge controllers and Cotek inverter. I do not stay there when the weather gets serious.