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Generators & Electric Motors General Discussion

Mep 017A neutral questions


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  #1  
Old 01-25-2005, 05:08:15 PM
Jon Gibson
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Default Mep 017A neutral questions

I know the subject of no neutral in 240v mode has been brought up several times. However, I only need 120v to run everything as my heavy load items are natural gas. (no central air yet) For the past several years I have used a smaller MEP 015A and just moved my extension cord from appliance to appliance, but that gets quite old after a couple days... . My goal with the larger unit I just purchased is to run everything (with some load management) just so the disruption during power outages will be reduced. My manual states that in 120V single phase mode, L2 and L3 are the lugs I want, but my question is, which would I use for neutral? Does it matter? In comparing the schematics of the two units, it look like it makes no difference. But I have never tied my little one into my panel as I plan to do with my larger unit. No matter what way I connect it, I still plan to drive a new ground rod specificaly for the generator. Any input would be appreciated!
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  #2  
Old 01-26-2005, 06:41:57 AM
Rich Mc Rich Mc is online now
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Default Re: Mep 017A neutral questions

On the old board this topic was discussed in detail and the results were that; using the 208v/3phase switch setting and connecting any two phases and neutral would deliver full power, if you can use the 208v instead of the 240v. It's the keep it simple principle.

Rich
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Old 01-27-2005, 04:28:54 AM
scottingvaldsen scottingvaldsen is offline
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Default Re: Mep 017A neutral questions

Take a volt meter to ground and l1 if you have volts its hot. measure l2 to ground and if there is no volts lt is is the neutral or ground
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Old 01-27-2005, 09:37:30 AM
Jim Rankin Jim Rankin is offline
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Default Re: Mep 017A neutral questions

Still the best way to tie into a 240 volt panel is to have the 120/208 with the neutral. That way your load management won't depend on which lugs your breakers are clipped on. If you use only the 120V setting, and tie into your panel, you could run a jumper to feed the other bus and the breakers clipped onto it, but then there is no possibility of even small 208-240V loads if you have any. Also the jumper will be a dead short if forgotten and transfered back to mains power!

Will you be installing a transfer switch or rigging up something like feeding in on a breaker to the main panel?

Jim
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Old 01-27-2005, 01:20:18 PM
Jon Gibson
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Default Re: Mep 017A neutral questions

Ok, I was considering that as an option. The main reason I wanted to run in 120v mode was so that load balance on the generator would not be of a concern. In a roundabout way I guess you could say I was going to use a jumper. I have a 4ga 5 conduction section of SOW cord, I plan to tin the ends and then hook two into my "hot" and then I can feed the two seperate sides in my panel. Then I would also run two of the others to the neutral. I am planning to purchase a DPDT transfer switch, however if the need arises before I get one and install it I have a no longer in use 50 amp dp breaker that used to feed my electric dryer. Most likely I will not need to do that, we typicaly lose power only in the spring and summer due to thunderstorms so I should have a few months.
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Old 02-01-2005, 11:38:37 PM
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Jim McIntyre Jim McIntyre is offline
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Default Re: Mep 017A neutral questions

Jon,

According to the schematic in the TM for the MEP-017A, L2 is the neutral, L3 is hot. To double check that, start the set, and with a voltmeter, measure the voltage between the wide (neutral) prong of the convenience outlet and L3. You should have 120V.

Why the TM doesn't just come out and identify which is hot and neutral is an indication to me that these sets were not that well thought out - and the TM's probably prepared by some low bidder! Also, the lack of a 120/240V setting seems like an oversight to me.

Anyway, if you have absolutely no need whatsoever for 240, go with the 120 setting, and jumper your two hots at the generator side of the transfer switch. But please double check the info I gave you - Your set may differ from the schematic in the TM.
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Old 02-02-2005, 08:09:41 AM
Jon Gibson
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Default Re: Mep 017A neutral questions

Thanks a bunch Jim! I spent a bit of time a couple nights ago going over a copy of the wiring diagram from the manual I have. However it was late and everything just started to run together. A job for more rested eyes I think. I will double check as you suggest, it would be prudent to make sure the wiring on the genset matches the wiring in the manual.

For anyone interested, if you have a Square D panel like I do, they offer kits to allow you to backfeed your panel with a breaker and have an interlock on it to prevent the utility and emergency feeds from being on at the same time. Not cheap given what little it involves, but for about $75 or so it looks like a very cost effective way to comply with code and eliminate the possibility of error. If you go to their website and look at the manual transfer kits, you'll find them.
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Old 02-02-2005, 01:37:22 PM
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Default Re: Mep 017A neutral questions

Jon,


The only thing that determines which was which was the fact than the convenience outlet was wired to L2 and L3, and the convenience outlet has a 'neutral' and a 'hot'. Neither L2 nor L3 are connected to the set's ground, so you'll need to deal with that at your panel, as was covered in another post on the subject.


Jim
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Old 02-02-2005, 02:23:15 PM
Jon Gibson
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Default Re: Mep 017A neutral questions

Ok, so then it basicly boils down to a saftey issue. Makes sense. As to grounding, if I understand the saftey aspects, it is fine to drive a ground rod to connect the generator frame to (as sepecified in the manual) but neutral should only be connected at the neutral bar inside my panel just to keep from messing up any GFI equipped items. I will re-read the posting on that subject, don't want to forget anything as importain as this.
Thanks again!
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