BearKiller

My generator has a 4-prong twist-lock receptacle that is stamped

120/240 VAC.

It appears that one prong is ground, one prong is 120 VAC - when used with ground, and the remaining two prongs are for 240 VAC.

Am I correct??

Or, do I have it all wrong??

I assume the prong with the protusion is the ground, right??

Someone that knows, please post a drawing of a four-prong, with the wires identified.

Thanks.

By the way, it also has two standard 110VAC duplex outlets; I know how to use them.

jrs_dodge_diesel

Not quite right.

The prong that has the bent side (a 90 degree bend) is ground.

Directly accross from that is neutral.

the two prongs on either side is 120 VAC hots.

2 hots (120 Volts) will make 240 Volts. A dryer or stove is a great example as they use 1 neutral pin and 2 hot pins.

Your standard house outlet will have a ground pin, a neutral (the wider blade), and a hot.

BTW here is a picture to help you out. I have a similar connection on my generator too. Its a NEMA L15-30.

Also if you are wiring up a plug here is the color code:

GREEN = Ground
WHITE = Neutral
BLACK = 120 VAC
RED = 120 VAC

BearKiller

Thank you.

That makes a lot more sense than the diagram that came with the generator.

TN Redneck

JR,

Thanks alot. I had the same question but didn't know where to find out. Shame on me for not thinking about asking here.

It amazes me the knowledge that is in our member's head.

DC

jrs_dodge_diesel

You're welcome. Glad to have helped.

SoTexRattler

Check the AMP rating of your 4P receptacle on the generator! They typically utilize either a 20amp 4prong 120/240v, or a 30amp 4prong 120/240v twistlock (as shown)depending on the size of the generator. They won't connect between sizes...
The 30's get pretty pricey because the mfr's know it is most likely for a portable residential hurricane generator...
K.

DmaxEter

Why am I thinking those plugs are for 3phase items only???? I dont know squat about electical other than it hurts when you touch it, but all the applications I have seen that plug used in were 3 phase. Is there anything to it or just what they wanted to use?

jrs_dodge_diesel

I guess you *could* use that plug for 3 phase. 3 phase requires 3 hot wires and a neutral. I have only seen the obove plug on small generators.

Racer9

I use mine to power the house during power failures. The two 120's feed each side of the main box, and I have everything working, including the 3 phase well. Of course I pull the main, so I'm not powering the whole neighborhood.

LeftLane

If you want a three phase twist lock plug you must buy a three phase twist lock plug. (locking pin grounded other pins live a three phase with neutral would be center pin ground locking pin neutral remaining pins live). Using plugs for applications other than their rated voltage and amperage can have seriously bad results. For instance if you were to have a 3 phase source that someone illegally connected to a single phase / neutral twist lock female plug and than plug a properly wired single phase / neutral male device in to it you would succeed in sending a live leg where the neutral should be thus destroying you single phase load!
I am a licensed electrician and have encountered numerous miss wired plugs, overloaded wires and otherwise dangerous situations over the years. My strongest advice is always to look at the electrical ratings (whatts, volts, amps, single phase 3 phase etc...) to be sure that what you are doing is safe.
These types of plugs are expensive because they are manufactured much stronger than residential grade devices and 30A plugs have to be larger with more conductor in them to accommodate the higher amperage.
Don't hesistate to ask if you need info on any electrical question.

Struggle

In pursuit of a geny I bought one for a week of camping but not in an actual campground situation. Anyway my point in this is it is my understanding that you cannot tie the two 120 volts sides of the plug together as then the generator will fight itself and let out the smoke if you know what I mean. Each side has to remain on its one side of the generator for being produced.

The reason I know this is I read into what I though was a generator that would run my camper A/C 120 camper uses a 30 cord to run everything at 120 volts. Well the generator os rated higher than 30 amps but only when using 220 plug wired per the factory but when you get to the 120 volts side of things one loses half the amp rating since the amps are doubled as you are using two sides at 120 volts.

When I bought my first gen before I got it out of the box it was then found out if I was running the camper at 220 the smaller one would work but since it is 120 (camper)I had to step up to a bigger gen that was able to handle a higher per leg 120 amp rating.

This was only a problem with the contractor type one I bought which is a Troy Bilt. Mine is rated at something like 5555 watts contious. I wired a dummy meter that when the lights go out I can just pull the meter out and put in the dummy meter in its place and hook up the neutral wire to the box itself (extremely important to have it hooked up) as meters do not carry the neutral wire in them as they only support the hot wires and fire up the gen and it powers the whole house. Everything but the hot water heater and A/C. It ran everything else. We found out one night when the power went out for a few hours and we were the only house in town that had power

My neighbors said I clearly did not know how to behave with out power

SoTexRattler

heh heh... In Jan of this year, the power went out for an extended period one night(abt 3 1/2 hrs). I had previously purchased a few L15-30 plugs and receptacles (ouch!)and had fabbed up an auxillary feeder cable that powers up my lighting main from my diesel genset. I went around the house and turned on EVERY light inside and outside the whole house to test it. I went outside to admire my "Grizwold" accomplishment and I had people driving by with this DUHH expression on their faces as they looked at the ONLY house on that side of town with any lights... It was Priceless!

DmaxEter, twistlock plugs & receptacles are pinned for many different current/voltages/phases by different width and # of prongs and prong orientation etc. For instance, the "L" looking keyed prong(some are a backwards "L") and by different diameter prong circle and such... Some CAN be forced into the wrong series receptacle with bad results...
The L15-30 (120/240@30Amp) used on generator receptacles is pretty expensive yet the same Mfr's 30amp rated 3phase 4prong twistlock plug (VERY similar,yet incompatible with L15-30) sitting right next to it on the shelf was 1/2 the price! Mfr's. know they've got a headlock on the consumer on this one...


K.

SoTexRattler

Whooops! I misquoted the model number on those twistlocks... I went out in the shop and looked at my 120/240VAC extension cord and realized my error.
They are L14-30 for the 30amp and L14-20 for the 20amp ones...
Also, the letter suffix(P or R) denotes Plug or Receptacle respectively...
I,e. L14-30R or L14-20P etc...

K.