Generator Voltage Output Help

Good evening,

I recently took delivery of a 2006 Nomad 2690 Travel Trailer.  Needless to say, I'm hooked on RV'ing.  However, I do have a question that nobody can seem to answer, so I'm going to try and be specific as possible.

My camper has the typical 30 plug as shown below.  Everyone has seen this type of plug before:

http://i66.photobucket.com/albums/h247/jjkz24/RV/t_4649.jpg

I recently purchased a 5000 watt, Husky generator from Home Depot.  The majority of the generators in the wattage are the same, as most of them have Briggs & Stratton, horizontal shaft engines.  On the generator, it has a 4-prong 30amp outlet.  Most commonly known as the L14-30 female recepticle.  This outlet is labeled 120/240v.  I will be utilizing this output on my RV.  My main question is,  how do I make sure that I'm not sending 240v to my RV?  There is no selector switch. 

Just for general info for everyone, these plugs have the following prongs:

1. A prong for 120v
2. Another prong for 120v
3. A neutral
4. A ground

I have found dog bones that convert to what I need:

http://www.pplmotorhomes.com/parts/rv-power-cords/power-grip-generator-adapter.htm

However, this is telling me that it more or less would be sending 240v to my RV by using an adapter such as the link above.

I then came across an adapter such as this:

http://www.gen-tran.com/eshop/catalog/966.asp

The link above clearly states:

        "PLEASE NOTE:  A 30 amp 7500 watt generator normally runs 30 amps to each hot blade on the receptacle.  Since the RV TT-30 is a 125-volt only device, only ONE hot leg of the plug is wired, and the other would be inactive.  Connecting this adapter to your generator for long periods of time may cause the windings of the generator to run imbalanced which could potentially shorten the life of the generator.  GenTran is not responsible for any damage caused by the use of this cord."

Is this the adapter I would need to make sure that I'm not sending 240v to my RV?

Here is a link to my owners manual:

http://bsintek.basco.com/BriggsDocumentDisplay/default.aspx?filename=feipxLXAnfBhU7y

On page 11, on talking about the 120/240v 30 amp recepticle, it states:

            "Use a NEMA L14-30 plug with this receptacle. Connect a
4-wire cord set rated for 250 Volt AC loads at 30 Amps (or
greater). You can use the same 4-wire cord if you plan to
run a 120 Volt load"

With this statement, how can I use the "same 4-wire cord" if I want to only utilize 120 Volt Load out of this output?

I'm so confused, and everyone I talk to in person gives me different answers.  The only one that makes sense is that whichever adapter I choose to purchase, I have to make sure that one of the 120v "hot" wires is not being used.

Does this make sense to anyone else?

Thanks in advance,

-Jason

A commercial dogbone will only connect one hot pin in the L14-30 plug to the RV socket (called a TT-30), giving 120 volts from hot to neutral when the L14-30 is plugged into a 120/240 source like your generator.

All of the NEMA plugs and sockets are specified for a specific voltages.  The L14-30 plugs into a 120/240 source with 120 volts available from either hot pin to neutral, or 240 volts available between the two hot pins.  A commercial adapter that uses a L14-30 to a TT-30 will most certainly be wired to connect to one hot pin on the L14-30 and leave the other one disconnected.

If you really, really want to be sure, get a voltmeter and measure the voltage while the adapter is plugged into the generator.    Or set the multimeter to "ohms" and see which L14-30 pins show up on the TT-30.

Jason,
    I believe that the 4 prong to 30 amp adaptor in your first link is what you want.  I am trying to get the info now but I believe they tie the two 120V legs together internally so you you both sides of the generator and it will be balanced.  If you look at your generator you will probably find only 15 amp circuit breakers.  By tying the two legs together you will get your full output and be balanced.  They are essentially doing in the adaptor what I would do to convert a generator to 120V from 120/240V.
Marinco also makes an adaptor from 4 prong to 30 amp.  I am trying to get a hold of my Marinco rep to get an answer now.

Thanks so much for the replies guys.  In doing more research, I'm finding from this article: http://www.rvforum.net/joomla/index.php?option=com_content&view=article&id=163:50-amp-shore-power&catid=37:electrical-power-systems-and-hookups&Itemid=45

Even though this is an article pertaining to a 50amp service, the theory applies to my question in regards to both hot poles of the recepticle, being sent to my RV.  Before I posted my question above, it came across as though I'd be sending 240volts to my RV, but that doesn't sound like it's the case.

That is an excellent diagram.  You can use the Gentran adaptor.  Their statement about unbalance is correct but usually only for heavier loads for long periods.  That being said, generators such as the one you bought are not designed to run for days on end.  They are for temporary power.  That is why most of the standby power generators are more expensive, because they are meant to run for longer periods of time. 
I am still waiting for Marinco to get back to me. 
As long as they advertise that it is a TT-30 you should not get 240V at the plug.

boatbuilder said:

That is an excellent diagram.  You can use the Gentran adaptor.  Their statement about unbalance is correct but usually only for heavier loads for long periods.  That being said, generators such as the one you bought are not designed to run for days on end.  They are for temporary power.  That is why most of the standby power generators are more expensive, because they are meant to run for longer periods of time. 
I am still waiting for Marinco to get back to me. 
As long as they advertise that it is a TT-30 you should not get 240V at the plug.

Click to expand...

So from what you are stating, if I use the adapter in the first link that I provided, I would be sending 240v, to my RV?  From the article that I just posted, I was getting the impression that the RV would be sharing between the two 125V legs, and not actually combining them to see 240v.

No the first one you linked to will not send 240V to your RV.  I was not clear on my post.  Sorry.  I believe that if they advertise it as going to a TT-30 receptacle you will be fine.  It is just a matter of how much power you can draw off of one leg of the 120V/240V plug.  I just do not know if they are using one leg or both.  When I say both legs I am talking both legs in parallel to neutral(120V) not leg to leg in series(240V). 

boatbuilder said:

No the first one you linked to will not send 240V to your RV.  I was not clear on my post.  Sorry.  I believe that if they advertise it as going to a TT-30 receptacle you will be fine.  It is just a matter of how much power you can draw off of one leg of the 120V/240V plug.  I just do not know if they are using one leg or both.  When I say both legs I am talking both legs in parallel to neutral(120V) not leg to leg in series(240V).

Click to expand...

Great!  Thanks for the reply.  Now this raises another question.  I'm now curious to the fact that since I'm only going to be utilizing one of the hot legs, that I'm wondering now if I'm going to be supplying enough power to my RV to power things such as my A/C and such.  My A/C is a 13,500btu unit, and I have things such as a microwave.  The water heater has the capability of running off of propane, so I'm not really concerned about that appliance.  However, I do have things such as 2 19" flat screen T.V's, and a "centralized" stereo.  Since I'm only using one hot leg, I have to assume that I'm not going to be able to use the generator's full 5000 running watts (6260 starting watts), to my RV.  I'm worried now about tripping the breakers.

Here's the link again to my owners manual to explain how it is setup.  Reference Page 11:

http://bsintek.basco.com/BriggsDocumentDisplay/default.aspx?filename=feipxLXAnfBhU7y  (Note: This manual is for a 5500 running watt generator, I have a 5000 running watt generator (20.8 amps for 240 Volts or two independent 120 volt loads at 20.8 amps each))

Jason,
    My Marinco rep just informed me that I are an idiot.  He is right.  Both adaptors you posted links to will work.  All of the commercially made adaptors use just one leg.  DO NOT hook the two hot legs together as I previously mentioned.  You can convert the generator to run straight 120V but it has to be done inside the control box.  I am truly sorry if I confused the heck out of you.  I should have looked in my generator books before I answered.
    If you use one of the adaptors you posted you will only get around 22 amps of power because that is all one leg of your generator will put out.  If you look at the circuit breaker above the L14-30 receptacle the breaker should be marked.  If that is the case you could save money and just buy a 30A to 15A plug and plug into one of the duplex receptacles that have a 20A breaker.

boatbuilder said:

Jason,
    My Marinco rep just informed me that I are an idiot.  He is right.  Both adaptors you posted links to will work.  All of the commercially made adaptors use just one leg.  DO NOT hook the two hot legs together as I previously mentioned.  You can convert the generator to run straight 120V but it has to be done inside the control box.  I am truly sorry if I confused the heck out of you.  I should have looked in my generator books before I answered.
    If you use one of the adaptors you posted you will only get around 22 amps of power because that is all one leg of your generator will put out.  If you look at the circuit breaker above the L14-30 receptacle the breaker should be marked.  If that is the case you could save money and just buy a 30A to 15A plug and plug into one of the duplex receptacles that have a 20A breaker.

Click to expand...

Excellent.  Thank you again for all of your replies.  I already have a 30 amp TT plug to a 15 amp "wall socket" dog-bone, but then I'm only limited to 15 amps.  I'll be buying a L14-30 to a RV 30TT dogbone later this week.  Hopefully, I won't be tripping any breakers.

On a side note, I've been finding a lot of useful, and helpful threads on this site.  As I continue to search and browse, a lot of interesting threads pop-up, and I'm learning a lot.  Thanks!!

The above has answered your question correctly.

FYI - the simpler answer to this problem is to measure the voltages if in doubt (even a little) -

a.  If you measure 220-240 VAC between L1 and L2, you have a 220 output that would work with the 50A connector of a MH or ?. (this is actually used as two 120 VAC circuits in most motor homes - exception might be an electric dryer or similar).

b.  If there is 0 VAC between L1 and L2, you have a single phase 120 VAC that can be safely connected together (see note below).

In either case both L1 and L2 should measure 120 VAC to neutral or ground.

Ernie

Yes, I will definitely be doing that.  However, my TT is only a 30amp 120v only.  So...I'll be using only one of the hot legs on the L14-30 on my generator.

I re-read (or read for the first time) the original post.

With that generator you may be able to get one of TWO RV adapters

Type one will have the 4=Prong twist lock, and a 30 amp RV socket.. This will work just fine,  it delivers 120 volt to your RV off ONE leg and completly ignores the other leg.

Another type (Not as easy to find usually) will have the same plug end but a 50 amp RV outlet.. If you find one.. BUY IT. and then use a standard 50-30 amp dog bone

WHY should you buy the more expensive 50 amp adapter?  Cause some day.. You may need it, and it's cheaper to buy it now then to buy a 30 now and a 50 later


P.S.  Should you decide to install an RV outlet at your residence... same advice, Go with a 50 amp and dog bone down

You can use 30 amp breakers if you like, but go with a 50 amp outlet.

John From Detroit said:

I re-read (or read for the first time) the original post.

With that generator you may be able to get one of TWO RV adapters

Type one will have the 4=Prong twist lock, and a 30 amp RV socket.. This will work just fine,  it delivers 120 volt to your RV off ONE leg and completly ignores the other leg.

Another type (Not as easy to find usually) will have the same plug end but a 50 amp RV outlet.. If you find one.. BUY IT. and then use a standard 50-30 amp dog bone

WHY should you buy the more expensive 50 amp adapter?  Cause some day.. You may need it, and it's cheaper to buy it now then to buy a 30 now and a 50 later


P.S.  Should you decide to install an RV outlet at your residence... same advice, Go with a 50 amp and dog bone down

You can use 30 amp breakers if you like, but go with a 50 amp outlet.

Click to expand...

Good advice, and thank you.  I had ordered a L14-30 - 30TT yesterday, and it'll be delivered tomorrow.  However, your suggestion is a good one.  I may consider that if I ever decide to run a line underground, from the breaker, and install a post where the RV currently resides.  Since my current multimeter has seen it's better days, I invested in a nicer one tonight from Lowes.  I'm going to be double checking my voltage output from the generator this weekend.  I haven't started the generator yet, as I just purchased it last Sunday morning.