# home generator too much volts



## idrinkalone74 (Feb 3, 2010)

Recently had a whole house generator installed with a transfer switch. At start up the generator put out too many volts damaging electronics and appliances inside. What would have caused this?


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## nap (Dec 4, 2007)

a defective generator


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## idrinkalone74 (Feb 3, 2010)

It is a Kohler and the company sent a guy out to look at it and said that it is working fine and that it was install fault?


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## Red Squirrel (Jun 29, 2009)

How much volts too much exactly? Most appliances should be able to tolerate more or less, if it's a small number. I would not run sensitive stuff off it, or at least, turn that stuff off during the transfer process. Having the sensitive stuff on a AVR UPS may help too.


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## Magnettica (Jan 13, 2009)

Were you drinking alone when you installed this genny?


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## vsheetz (Sep 28, 2008)

idrinkalone74 said:


> It is a Kohler and the company sent a guy out to look at it and said that it is working fine and that it was install fault?



If he said it was a faulty installation, you need to get the details of what is wrong from him.


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## nap (Dec 4, 2007)

since the generator is self regulating, a problem with the generator is the only problem for it to produce too high of a voltage.


Now, if the installer did something dumb like flipping the neutral and 1 hot leg or failing to hook up the neutral, that would cause appliances to experience too high of a voltage but the generator would not be producing too much voltage which is what you said was the problem.

so, did the appliances receive too much voltage and that is all you know or did the generator put out too much voltage?


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## Gigs (Oct 26, 2008)

Could have been a broken neutral. That can cause overvolting even if the generator is fine.


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## micromind (Mar 9, 2008)

Does this generator have an adjustable voltage regulator? How about an electronic governor?

Small generators usually don't have an adjustable voltage regulator. Instead of an actual regulator that drives the field current, they use a capacitor. This results in the voltage following the speed of the generator rather than independent regulation.

Most of these units don't have an electronic governor, thus the speed is set slightly high at no-load, and it'll be slightly low at full-load. 

It's pretty common to see 130 or even 135 volts at no-load, and 110 or even 105 volts at full-load. The frequency will vary as well, from 65HZ or so, to about 55. 

Just about any non-electronic load can easily handle this variation, but electronic stuff doesn't do too well with it. Most UPSs won't run on any gen that doesn't regulate voltage and frequency exactly.

Another thing I've found to be a problem is distortion of the AC waveform. A big gen will produce an almost exact sine wave, smaller ones won't. Lights, heaters, and motors can handle a distorted waveform (to a certain extent anyway), electronics can't. The only way to see this is with an oscilloscope. Sometimes I just laugh when I hook mine up!

You can certainly turn the governor down a bit, and the voltage will be lower, but it'll be even lower with increasing load. Sort of a balancing act.

Did the tech check both voltage and frequency? If so, what were the readings? 

Rob


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## idrinkalone74 (Feb 3, 2010)

The electrician said that he did nothing wrong during installation. When it was first fired up it ran for a bit and things inside the house smelled hot. It turned out to be a balist for a light that was smelling hot. Shortly after that we checked appliances and evertyhing dealing with electronics wasn't working. The electrician checked the generator and he said it was putting out 170 volts. He looked for an adjustment on the generator but there was none. He did tighten down the small lugs at the generator, checked the volts again and they were fine (120). Could a loose wire have caused t his?


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## kbsparky (Sep 11, 2008)

Yup. Loose neutral can cause this. Bad installation, it would seem.


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## nap (Dec 4, 2007)

I will almost bet that in the installation instructions there is a directive to tighten all bolts, nuts, and terminal connections. If it is there, the electrician is clearly at fault. If it isn't, it still is really his fault. You do not energize the house until you fire and test the generator without a load on it.

bad installer, bad.


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## oilseal (Aug 24, 2009)

After all of the above, I would never feel comfortable using my computer, TV, and anything else electronic while being powered by a standby generator.


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## nap (Dec 4, 2007)

oilseal said:


> After all of the above, I would never feel comfortable using my computer, TV, and anything else electronic while being powered by a standby generator.


if you use a UPS for any electronics, those problems are at least minimized but if the UPS is adequate and functioning properly, should be entirely removed.

so, the sales pitch (and no, I do not sell UPS's)

your computer should be on a UPS. You should have lighting arrestors, surge protectors, what ever you want to call them, at your main panel and at each individual circuit that feeds anything electronic. Each level or subsequent surge protector is designed to be more sensitive as it gets closer to the actual appliance. That allows multiple levels of protection so where there may be an extreme surge that could realistically jump through a branch end protector, a main panel protector will have a better chance of shunting that high level surge and providing protection. Then, as a lesser surge is passed to the branch circuits, those protection devices in those circuits, which are not able to handle the huge surge, do what they do and protect the circuit from that lower level of surge.

so, as those devices protect against surges, a UPS will protect against sags. How it does that is simply, it is a battery that is continuously charged by the premises power and depending on the quality and specs of the particular UPS, uses internal electronics to make sure that the voltage remains within a predetermined range. Along with that, and again depending on the specs of the particular UPS, the wave form is controlled by the UPS as it actually creates it's own wave form. Think of it as taking premises power (AC), converting it to power stored in a battery (DC), and then using that stored power to produce AC power at a designed voltage level with the proper wave form for the appliance.

Obviously, there are huge differences between a $100 UPS and a $100,000 UPS and the quality of power available from either unit will vary due to the design of the unit.

but, generally, anything is better than nothing.


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