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AssuredElectrical
AssuredElectrical, Master Electrician
Category: Electrical
Satisfied Customers: 4241
Experience:  Contractor-42+ Years in the ElectricalTrade
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My generator has a 4 prong 240v out let that I am trying to

Customer Question

My generator has a 4 prong 240v out let that I am trying to split down to 2 120v supplies. Each hot leg Wigs 117v when metered to the neutral. The problem is that when I use one leg the other leg spikes to 164v. Not sure why it would go out of ba***** *****ke that??
Submitted: 1 year ago.
Category: Electrical
Expert:  AssuredElectrical replied 1 year ago.
Welcome. My name is ***** ***** would be glad to assist.What type of load is on each of the phases?Tell me exactly how the items are wired on the cord that plugs into the generator receptacle.Let me know and we can continue,Thanks
Customer: replied 1 year ago.
Hi Tommy,
1) phase 15 amp A/C unit Old style hard start
2) phase 8 amp A/C with soft srartI fire up the soft start and it runs fine but the other leg spikes so I haven't tried to use it.
Wired Black hot, Red hot, White common, Green ground.I would have to take the cord cap apart to give you the Alpha characters but the two hot legs are on the sides, neutral at the top and dog leg ground on the bottom.
Expert:  AssuredElectrical replied 1 year ago.
Ok, thanks.Need the wiring so lets try it this way if we can.You have a cord with a male plug and plugged into the generator receptacle, correct?On the other end of the cord, you wire to what?Straight to the appliances?To receptacles?Or?How and where are you measuring?Everything is wired and ready, correct? Nothing disconnected, correct? Details and then we can move forward.
Customer: replied 1 year ago.
yes
1) Direct wiring to Hard Start A/C unit. About a 50' run.
2) Wired to cabin Panel. There are other outlets on this circuit but none are in use.(soft start)
Measuring with a Fluke meter.
Measuring 1) at the wire nut for the A/C unit (hard start)
Measuring 2) at the outlet that the A/C is plugged into.(soft start)
Everything wired and ready
Expert:  AssuredElectrical replied 1 year ago.
Ok, thanks.I believe all you have is an excitation situation.Since you have no load on the one phase, the windings are sitting in limbo, so to speak.The other phase needs excitation to begin to balance and produce some current.Take a simple lamp and plug into one of the receptacles. Even a high voltage is not going to do any damage to a standard household lamp.See if that doesn't begin the the excitation process within the generator.Turn on the lamp or even 2 if you have them before starting the AC unit on the other phase.You are trying to put the generator at a great imbalance to start with the AC unit.Always best to have a 220 volt AC unit to keep the phases balanced in current, which also keeps the voltage balanced
Customer: replied 1 year ago.
I will try as you have suggested but if that is the case, I will have to leave lamps burning all of the time because the A/C cycles on and off. At the very least I will have to add some other load to the direct wiring to the hard start A/C unit. This is a cabin in the middle of nowhere. I'm just trying to get the most out of the generator because the 120v side is only 20 amps and the 240v side is 30 amps.
Expert:  AssuredElectrical replied 1 year ago.
No, actually you need to do nothing if the test holds true.As soon as anything is started the voltage will drop on the other phase.It is not like it is going to be at the high level for any amount of time and then drop if its excitation.It will be in a 1/4 cycle is which equal to you blinking.It will not hurt a thing nor cause any issues.
Expert:  AssuredElectrical replied 1 year ago.
If it doesn't change is the problem. That will be a generator issue and needs work.
Expert:  AssuredElectrical replied 1 year ago.
One thing I just noticed on the write up."I'm just trying to get the most out of the generator because the 120v side is only 20 amps and the 240v side is 30 amps"I do not suggest having a phase imbalance of 30 amps on a generator.you are supposed to always balance as close as possible on them.That is why the receptacle is made to connect to a 120/240 volt panel and then distribute power, not for direct wiring.
Customer: replied 1 year ago.
I will give it a try but the Hard Start A/C is direct wired so I will try starting it first because I can add a load to the other leg.
Generator is new but who knows. Will get back to you. Thanks
Expert:  AssuredElectrical replied 1 year ago.
Ok, very good.Some AC units can pull 3-5 times normal at starting, so the generator must be large enough for the application.
Customer: replied 1 year ago.
Are you suggesting that I wire the 240 to my panel and then draw the power to both A/C units from there
Customer: replied 1 year ago.
I think I will dump the Hard Start and get a soft start just in case.
Expert:  AssuredElectrical replied 1 year ago.
With generators, i ti best to have a separate panel.You wire form the main panel to that panel, then from the generator to that panel.That becomes your emergency circuit panel. Only has the items for emergency useYou interlock the breakers, so only one power source at a time.Then you have a safe and viable installation.Your way is time consuming when you need the generator and takes time etc.I prefer quick and no work setupsYou can do it your way, just not suggested.
Customer: replied 1 year ago.
There is no main panel. It is a generator or nothing. I'm way out and stand alone.
Expert:  AssuredElectrical replied 1 year ago.
Ok, then just install a small panel with the circuit breakers you need.Then pre-wire the genny to it and be ready at a moments notice.this allows for later if you add any solar or another generator and have backup.Panel is best either way.
Customer: replied 1 year ago.
Got it. Will let you know the out come.
Expert:  AssuredElectrical replied 1 year ago.
Ok, thanks