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240V gen outlet does not produce 120 but has L14-30P connection

5.8K views 12 replies 5 participants last post by  somedumbguy  
#1 ·
I have a 15 year old "Nikota" 3000/3500W generator. It has performed pretty well as a home backup during power outages. I've always used 120V only via extension cords through the window and all around the house. This generator has a selector switch for 120 vs 240 operation, a 120 outlet and a L14-30 connection. (There are no GFIs). I understand the L14-30 is what is used to feed the house though an inlet box connected to the house main panel through a 240V breaker controlled by an interlock. I decided to install this set up. Before connecting the gen to the house, I tested it at its 240 receptacle. The generator produces 240 across the "X" and "Y" terminals but does not produce 120 from the X or Y terminal to the neutral. The wiring diagram is on a label on the case (hard to read). It appears that the neutral terminal of the L14-30 connection isn't connected to anything inside the generator! I opened the case and confirmed that is true. I got one opinion that this is a "floating neutral" generator and it needs to be connected to the house in order to obtain a neutral bonded to ground. I connected it up to the house with only two 120 circuit breakers turned on (one X and one Y) with no loads and measured the voltage. It was not 120 or zero; It was 28V. When I tuned off one circuit breaker, the voltage on the other dropped to about 14V. Any ideas? I was going to try a few more tests but thought I better quit while the gen still functions on extension cords and the house wiring is undamaged! Attached are pics of the wiring diagram.
 

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#3 ·
Thanks iowagold; I'll check the switch again. First time I looked it seemed unburned but maybe a little corroded. What do you think about the fact that the neutral connection of the L14-30 receptacle is not connected to anything inside the generator just as the wiring diagram shows? Can that possibly work and produce 120? There is absolutely nothing in the manual about 240 operation. I'm starting to think that the gen was never intended to produce 120 and 240 at the same time and they simply put the wrong type of receptacle in the gen (?)
 
#6 ·
some of those gens are not like the later GOOD gens.
you only had a choice of 240 or 120 volts...
this generator looks like it is one of those that you do not get both at the same time.

I would use another generator for a whole house setup.

sell this one and get a better for your use unit.
 
#4 ·
With the switch in the 120 position, both windings are in parallel, as are the two 120vac receptacles. With the switch in the 240 position, the windings are in series, centrally connected by the brown wire, which should serve as the neutral. It's really strange why the manufacturer did not connect the brown wire to the neutral conductor of the L14-30 receptacle. If that generator was mine, that's what I would do, but that's just me. BTW, you can do a lot of damage to household appliances by wiring 240 without a neutral to your house.
 
#5 ·
Thanks motormonkey. I'm going to give that a try. Having read various posts on hooking up a generator to the house panel recently, I have an idea about why the manufacturer did this. I'm wondering if the generator hookup is not strictly legal when connected to the house in this manner. So they leave it to the owner to figure it out and make the modification. That way they can avoid liability if I toast myself, I suppose. Fair enough.
 
#8 ·
iowagold; that would be the smart thing to do. But getting to the bottom of this riddle has become a personal challenge!! I probably will get another gen; this one is pretty old; I wouldn't want to have to rely on it in a 3+ day outage when its hard to buy a replacement. Actually, gen selection/availability seems to be a little low right now; must be high demand caused by the west coast fires and storms in other parts of the country.
 
#11 ·
Hi gang; I did modify the generator by connecting the pins already connected together with the brown jumper wire to also connect to the neutral of the L14-30 receptacle. When the generator is switched to "240V" mode it now produces 120 at both of the "hot" terminals of the L14-30 measured to the neutral terminal and also measures 240 across both hot leads. Eureka! (When switched back to 120 mode, the generator produces 120 at the 120V receptacle as expected).

I would go ahead and hook up to the house panel via the L14P connection now except for one thing. There is voltage at the generator from both the "hots" to ground on the L14P that measures from 132 on one hot leg, ,61 on the other hot leg, and 36 from neutral to ground. (Adding all this up is 229V which is pretty close to 240). Is this because the generator has a "floating neutral"? When the generator is not running there no continuity from neutral to ground. I'd like to think that when I connect it to the house, the neutral and ground get bonded at the house panel and everything will be fine. I would like to simulate that first by jumping the ground and neutral together at the generator L14-30 somehow.
Any thoughts/advice?
 
#12 ·
The ONLY place where neutral and ground should be bonded together in you house is either in the main panel or in the meter box. If you hook a generator into the house panel, the neutral and ground in the generator should not be connected together. As it currently is, that generator is good to go for operation on your house circuit. If you run the generator independently from the house, it's usually a good idea to hook the neutral and ground together in the generator. Given that crazy switching in that generator, that could get a little complicated.
 
#13 ·
thanks motormonkey. my next step is to test it connect the generator to the house with all breakers off except for two circuits; one on each 120 leg, with everything unplugged except for an old toaster and blow dryer nobody will miss if they get damaged. I'll check some voltages and maybe currents and see if anything looks funny. I'm waiting for a time when everyone else is out of the house for a couple hours.
At some point I will buy a new generator and use this old one to backup/rest the new one during an outage. I'm waiting for availability of gens to improve before I buy a new one.