EMS-HW50 Reverse Polarity with Generator

cboss · 07-15-2021, 05:56 PM

I've searched a bunch of forums/posts and I'm still confused.
I installed a PI EMS-HW50 last year and tried the Briggs & Stratton P3000 Generator for the first time last week. We normally use shore power, but will be doing some boondocking next month. I've never had a problem with shore power or my 30 amp plug at home when using the EMS-HW50.
At first the EMS thru an E2 code (open ground). Ordered and used the Hughes Autoformers Ground Neutral Plug and now get the E1 code (reverse polarity).
I've read this older forum (https://www.forestriverforums.com/fo...on-181147.html) couple of times, but am still a little confused.
Is there an easy fix for this or should I just use the genny bypassing the EMS?
Thanks in advance for any advice!

**wmtire** · 07-15-2021, 08:30 PM

Do you have a multimeter and are familiar with how to use it?

cboss · 07-16-2021, 06:15 AM

Quote:

Originally Posted by wmtire

Do you have a multimeter and are familiar with how to use it?

Yes, I'm good with a multimeter. I have a Fluke. I'm usually very good with this stuff, but I'm kinda stumped here.
I'm thinking I need to reverse the ground and neutral, but not sure how to do that. The plugs are all sealed. I'm thinking of making a "pigtail" just for when I use the genny, as it all works at home and in the CGs.

**wmtire** · 07-16-2021, 06:38 AM

Quote:

Originally Posted by cboss

Yes, I'm good with a multimeter. I have a Fluke. I'm usually very good with this stuff, but I'm kinda stumped here.

I'm thinking I need to reverse the ground and neutral, but not sure how to do that. The plugs are all sealed. I'm thinking of making a "pigtail" just for when I use the genny, as it all works at home and in the CGs.

Reverse polarity is normally the hot and neutral reversed. Since the neutral is also current carrying to complete the circuit, most 120 volt items will work with reverse polarity.

As the link you provided up above, the OP in that thread found an outlet on his generator was miswired.

Your ems though will not allow power past it when it senses miswired configurations.

Just to get a clear picture on this, you are using an inverter generator....which will require a ground/neutral bonding plug that you say you purchased from Hughes, .....and now what kind of outlet are you plugging into on the generator? 50, 30, 20, 15 amp? Are you using any adapter?

cboss · 07-16-2021, 06:49 AM

Quote:

Originally Posted by wmtire

Reverse polarity is normally the hot and neutral reversed. Since the neutral is also current carrying to complete the circuit, most 120 volt items will work with reverse polarity.

As the link you provided up above, the OP in that thread found an outlet on his generator was miswired.

Your ems though will not allow power past it when it senses miswired configurations.

Just to get a clear picture on this, you are using an inverter generator....which will require a ground/neutral bonding plug that you say you purchased from Hughes, .....and now what kind of outlet are you plugging into on the generator? 30, 20, 15 amp? Are you using any adapter?

It is an inverter gen, B&S P3000. The Huges plug got rid of the "open ground"; that's when the "reverse polarity showed up. The outlet on the gen is 30 amp and I am using an adapter

**wmtire** · 07-16-2021, 06:52 AM

If I am reading your first post correct, you are using a 50 amp EMS according to the model number. You then say you plug into a 30 amp outlet at home. I assume you are doing this via an adapter as your RV is a 50 amp? Is this correct?

**wmtire** · 07-16-2021, 06:53 AM

Quote:

Originally Posted by cboss

It is an inverter gen, B&S P3000. The Huges plug got rid of the "open ground"; that's when the "reverse polarity showed up. The outlet on the gen is 30 amp and I am using an adapter

This adapter is what I would want to look at first as it could have the hot and neutral reversed internally in it. This a different item being introduced in the circuit that you have not used previously.

But as I asked earlier, do you have a 50 amp RV?

cboss · 07-16-2021, 06:56 AM

Quote:

Originally Posted by wmtire

If I am reading your first post correct, you are using a 50 amp EMS according to the model number. You then say you plug into a 30 amp outlet at home. I assume you are doing this via an adapter as your RV is a 50 amp? Is this correct?

yes, correct, normal Camco 30 to 50 adapter

cboss · 07-16-2021, 06:57 AM

Quote:

Originally Posted by wmtire

This adapter is what I would want to look at first as it could have the hot and neutral reversed internally in it. This a different item being introduced in the circuit that you have not used previously.

But as I asked earlier, do you have a 50 amp RV?

yes 50 amp RV

cboss · 07-16-2021, 07:14 AM

I'm thinking of using a plug like this (I can access it) and making a pigtail from a Camco 30 - 50 adapter just for generator use. That way I don't need the adapter and I can reverse the hot and neutral if necessary.

**wmtire** · 07-16-2021, 07:16 AM

Quote:

Originally Posted by cboss

yes, correct, normal Camco 30 to 50 adapter

Quote:

Originally Posted by cboss

yes 50 amp RV

So we actually have two adapters being used simultaneously. You are using a 50 to 30 adapter, then plugging that one into a 30 amp twistlock adapter for the generator? All these details matter as there are connections that can be incorrect.

Before I would look at the generator, I would check the adapter(s). I know you have been using the camco adapter at home with the EMS and no problems, but we don't know if your 30 amp outlet at the house is miswired. Let's just assume at this point it is wired correctly and focus on the twistlock adapter.

You want use the multimeter to check continuity from the front slots of the twistlock adapter to the prongs on the back. We are trying to ascertain if the hot and neutral are reversed internally. To do this you need to know which is supposed to be the hot and neutral when looking at the front of the twistlock. Ground is at top, neutral is at 5 oclock position and hot is at 7 oclock position.

Your generator may have a schematic on it where the 30 amp twistlock outlet is that shows where the male prong go in as to what is hot and neutral. I don't have a schematic handy.

We are just wanting to make sure the front of the twistlock and the rear of the twistlock match up for what it hot and neutral.

cboss · 07-16-2021, 07:29 AM

I just rang it out. Adapter is good. Checked it with the gen schematic and a 30 amp 120v plug I googles.

CHICKDOE · 07-16-2021, 08:26 AM

did you ever confirm that the generator receptacle is wired properly and is not reversed?

cboss · 07-16-2021, 08:36 AM

Quote:

Originally Posted by CHICKDOE

did you ever confirm that the generator receptacle is wired properly and is not reversed?

No I've not confirmed that yet.

**wmtire** · 07-16-2021, 08:36 AM

That is the next step. To make sure there is 120 volts on the generator twisttlock outlet hot by testing the hot and ground to get 120 volts with the generator running.

There should be zero or next to zero volts when testing neutral and ground

If you get 120 volts with neutral and ground... but no volts with hot and ground then it's probably reversed.

cboss · 07-16-2021, 09:43 AM

It is the generator wiring.
Instead of trying to rewire the gen I made an adapter. It works great, I just finished testing it. Ran it for 20 minutes, EMS likes it, AC kicks fine, No heat in any of the connections. Liquid tape is drying as I post this.

wmtire...THANK YOU! Next time I'm in LA I'll buy you a beer.

**wmtire** · 07-16-2021, 09:56 AM

Quote:

Originally Posted by cboss

It is the generator wiring.

Instead of trying to rewire the gen I made an adapter. It works great, I just finished testing it. Ran it for 20 minutes, EMS likes it, AC kicks fine, No heat in any of the connections. Liquid tape is drying as I post this.

wmtire...THANK YOU! Next time I'm in LA I'll buy you a beer.

Excellent. I'm going to hold you to it. Thanks.

Edit: your ems did what it was supposed to

Gmar60 · 07-16-2021, 04:40 PM

Because my generator is not grounded, my EMS shows fault. I made a neutral bonding plug and error goes away. Common problem solved.

cboss · 07-16-2021, 04:51 PM

Quote:

Originally Posted by Gmar60

Because my generator is not grounded, my EMS shows fault. I made a neutral bonding plug and error goes away. Common problem solved.

Yes, but in this case there were two problems.
First "open ground" - solved with a bonding plug.
Second "reverse polarity" - solved with the adapter I made or rewiring the generator.
Didn't know about the second problem until the first one was solved. EMS shuts down for either one.

CHICKDOE · 07-16-2021, 05:35 PM

i understand that you have it resolved but a couple of comments.

to make the grounding plug you probably used a 15 or 20 amp outlet. for the grounding plug to work you had to bond neutral to ground. if you did this as normal that generator outlet must be wired properly.

the 30 amp outlet is wired improperly. should you ever lend it to somebody or use it without you adapter you could have the same issue. worse might be that there is no ems involved and the load actually sees reversed polarity.

should somebody pick up you adapter and plug it into a properly wired generator the load will see reversed polarity.

i know it is work but is there any chance or either returning the generator and having it corrected or correcting it yourself?

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