MEP-802 and 803 Main generator tip.

NormB · Oct 10, 2016

****, I shoulda known this one. Thanks. I hate meeses to pieces.

jkmooremd · Oct 10, 2016

I have been scoping out mep 803a threads, and this seems the most likely and recent to help with my problem. I purchased a surplus 2010 mep 803a with only 34 hours on it. The accessories evidently had never been used. The only thing is was missing was the fire extinguisher.

New batteries , oil, and coolant, and it started right up. Everything seemed to work fine. I need it to be portable between two homes, one of which is on the coast. In preparation for hurricane Matthew I set it up to supply the house in case of outage. Set it for 120/240 V single phase. Accessory outlets worked fine. Main lugs showed L3-L1 at 240V and both L3-L0 and L1-L0 at 120 V. 60 hz and steady.

I wired it with 6 gauge copper to a subpanel in the garage thru a 50A plug and breaker. Hot leads and neutral to same in the panel. Intended to backfeed the main house panel when utility feed is disconnected. No power outage during the storm, so I decided to test the concept the next day.

Disconnected from utility. Isolated the garage subpanel. Started the generator and all looked fine. Flipped the breaker to connect to the garage panel. A surge protector popped and burned, as did all three of my garage door openers. A 240V outlet showed 240V. One 120V outlet showed 34 V and another showed 190V. By the time I flipped off the breaker and got back to the generator, all specs there were normal.

Any idea out there what happened. I'm afraid to test it further for fear of destroying more electronics. But I'm not willing to give up on the 803. Any help would be much appreciated. Thanks.

DieselAddict · Oct 10, 2016

Disconnect it from the house and load test it.

Build a rig out of portable heaters or waterheater elements in a big container of water.

It sounds to me like you flipped a hot with a neutral somewhere. Go back over everything. Especially the plugs.

Daybreak · Oct 10, 2016

jkmooremd said:
I have been scoping out mep 803a threads, and this seems the most likely and recent to help with my problem. I purchased a surplus 2010 mep 803a with only 34 hours on it. The accessories evidently had never been used. The only thing is was missing was the fire extinguisher.

New batteries , oil, and coolant, and it started right up. Everything seemed to work fine. I need it to be portable between two homes, one of which is on the coast. In preparation for hurricane Matthew I set it up to supply the house in case of outage. Set it for 120/240 V single phase. Accessory outlets worked fine. Main lugs showed L3-L1 at 240V and both L3-L0 and L1-L0 at 120 V. 60 hz and steady.

I wired it with 6 gauge copper to a subpanel in the garage thru a 50A plug and breaker. Hot leads and neutral to same in the panel. Intended to backfeed the main house panel when utility feed is disconnected. No power outage during the storm, so I decided to test the concept the next day.

Disconnected from utility. Isolated the garage subpanel. Started the generator and all looked fine. Flipped the breaker to connect to the garage panel. A surge protector popped and burned, as did all three of my garage door openers. A 240V outlet showed 240V. One 120V outlet showed 34 V and another showed 190V. By the time I flipped off the breaker and got back to the generator, all specs there were normal.

Any idea out there what happened. I'm afraid to test it further for fear of destroying more electronics. But I'm not willing to give up on the 803. Any help would be much appreciated. Thanks.

Howdy,
What was grounded? Connection to house system requires ground bond bar on generator to be removed. All 4 wires need to be connected. Whatever your doing, all breakers should be off. Double check your wiring. Double check your breakers and panel. Find 1 true breaker after generator is connected and providing power. Say 1 breaker with nothing attached. check the power at the plug.

How long have you run this generator? You need to load test it and run it a good long time the ensure you can depend on it.

DieselAddict · Oct 10, 2016

Daybreak said:
Howdy,
What was grounded? Connection to house system requires ground bond bar on generator to be removed. All 4 wires need to be connected. Whatever your doing, all breakers should be off. Double check your wiring. Double check your breakers and panel. Find 1 true breaker after generator is connected and providing power. Say 1 breaker with nothing attached. check the power at the plug.

How long have you run this generator? You need to load test it and run it a good long time the ensure you can depend on it.

Jinx, you're it.

rhurey · Oct 11, 2016

Sounds like loose / broken / open neutral somewhere.

240V Line to Line, 34V L1 to N, 190V L2 to N add those two and get 224V.

This is what happens when the neutral doesn't return to the power source, you get the power driven through L1 to N, and then from N to L2. But the voltage lost in each leg is a function of the unbalanced resistance of the two circuits instead of a constant.

DieselAddict · Oct 11, 2016

rhurey said:
Sounds like loose / broken / open neutral somewhere.

240V Line to Line, 34V L1 to N, 190V L2 to N add those two and get 224V.

This is what happens when the neutral doesn't return to the power source, you get the power driven through L1 to N, and then from N to L2. But the voltage lost in each leg is a function of the unbalanced resistance of the two circuits instead of a constant.

That is another great (in a bad way) possibility.

jkmooremd · Oct 11, 2016

Thanks for your responses. I'm thinking the problem is with the grounding. I grounded the generator ground to a rod in the ground. I did not remove the ground bar. Should I have run the generator ground to the house ground? I'll check all the wiring in the panel again, but all seemed OK. Not sure what "all 4 wires need to be connected" means unless you mean the ground wire as the fourth. Nothing is connected to L2.

This generator has actually never been used. I'll see if I can hook up some load test setup this weekend. Thanks.

Daybreak · Oct 11, 2016

jkmooremd said:
Thanks for your responses. I'm thinking the problem is with the grounding. I grounded the generator ground to a rod in the ground. I did not remove the ground bar. Should I have run the generator ground to the house ground? I'll check all the wiring in the panel again, but all seemed OK. Not sure what "all 4 wires need to be connected" means unless you mean the ground wire as the fourth. Nothing is connected to L2.

This generator has actually never been used. I'll see if I can hook up some load test setup this weekend. Thanks.

Howdy,
For safety, you might want to contact a electrician.

4 wires for single phase 120/240 would be 2 hots, 1 neutral, and 1 ground.

Connected to house service panel = you are using the panels grounding system. The ground bonding strap is then removed. With it being removed, you need to have all 4 wires connected to panel to ensure safety.

In the middle of a field = ground rod in the ground, wire to generator ground lug, ground bonding strap in place.

You would remove the ground bonding strap

DieselAddict · Oct 11, 2016

The more I think about it I agree that you have a probllem with the neutral somewhere.

Guyfang · Oct 11, 2016

Using your house as a load bank is never good. Go to the junkyard and find an old stove or three. A dryer or two. Anything with heater elements in it.

I will admit here, for training purposes only, that I once hooked up cables wrong and had phase on neutral. And the results sound like what happened to you. Before you take it all apart, make some pictures of how you hooked it up. You can look for the mistake. Also to remind you to be careful.

dependable · Oct 11, 2016

I'll second what Guy said, and also sounds like neutral problem to me.

I was doing a R-3 adjustment on an 003 once, using house as load, all wired up proper, interlock locked, I accidentally tripped over the neutral while reading multi-meter, it ripped out of lug. Ha, the shop lights blinked alternately then burnt out, my boiler control burst into flames and I fried several "wall wart" transformers. Good thing my wife was away haha.

jimbo913 · Oct 11, 2016

I would have an electrician check your setup. It concerns me that you back feed a sub panel, where on my setup I back feed an interlock protected breaker in my main which feeds my sub.
It is my understanding that in a sub panel you do not bond neutral to ground but maybe you have and power went to ground? Just a thought as I am no trained electrician.

lonesouth · Oct 12, 2016

jimbo913 said:
I would have an electrician check your setup. It concerns me that you back feed a sub panel, where on my setup I back feed an interlock protected breaker in my main which feeds my sub.
It is my understanding that in a sub panel you do not bond neutral to ground but maybe you have and power went to ground? Just a thought as I am no trained electrician.

I previously backfed a sub-panel as well. There should not be any issue with the ground/neutral bonding as the ground and neutrals should be connected at the main panel. Ground and neutral are not switch with the breaker, but are continuous regardless of whether or not the sub-panel has power to it. Interlock only protects the mains lines from being powered by the generator, but does nothing to impact ground/neutral.

jimbo913 · Oct 13, 2016

Type "neutral bond at sub panel" in a search engine.

"If you have the grounding and grounded (neutral) bonded at the second panel, you will have current on the grounding conductor. If for any reason the grounded (neutral) drops out, all the current will be on the grounding conductor."

sandmanxx · Oct 22, 2016

Hard Head said:
Some info on the diodes used IN5406. I replaced the diodes in the units I service with IN5408. The peak reverse on the 5406 is 600v and the 5408 is 1000. The normal voltage is 700 vs 420. Everything else is roughly the same. See chart View attachment 647745

Words can't say enough - many thanks.

Any particular brand ?? or info one should know other then item mentioned??

lonesouth · Oct 22, 2016

I've got extra MOVs if anyone needs one, PM me your address and I'll drop it in the mail.

sandmanxx · Oct 22, 2016

Sure and thanks

Charles Kennedy
326 East Rampart Drive
San Antonio, Texas
78216

When I go pick something up - I send a electrical item xmas to you!

I am also going to look at the fixing the board as well. I am not a electrical wiz - put i manage. My father now 99 years old -
Was Duty, Chief of Staff in Electrics at RAFB in San Antonio. RAFB got its first radar via my dad lol ..

Thanks again

MtnSnow · Oct 25, 2016

Thanks to Kloppk for sending me a couple of MOVs, I just finished doing the VR Fuse (I used the MDL-3 type fuse as listed in the PSMag article for this enhancement as I was able to get them locally much cheaper than the other listed model in this thread) & the MOV upgrades to my 2007 Mep-803a this evening after work.

I will pay it forward and offer a couple of extra (4) MOVs that I ordered and (1) extra fuse holder that I picked up that I will not be using. (Sorry to others as they have been spoken for and mailed out)

Sodamo · Oct 25, 2016

MtnSnow said:
Thanks to Kloppk for sending me a couple of MOVs, I just finished doing the VR Fuse (I used the MDL-3 type fuse as listed in the PSMag article for this enhancement as I was able to get them locally much cheaper than the other listed model in this thread) & the MOV upgrades to my 2007 Mep-803a this evening after work.

View attachment 651154

I will pay it forward and offer a couple of extra (4) MOVs that I ordered and (1) extra fuse holder that I picked up that I will not be using.

I'd be interested as my 803 doesn't have the mod.
PM me

MEP-802 and 803 Main generator tip.

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