Too much voltage 246v from power company

[LeroyDriver]

To anyone with advice,

I've had 2 refrigeration compressors go bad because of too much voltage from panel to condensing unit. Currently 246v. I've solved the problem with a transformer but have this question for all you electricians.

Why does the power company say "they are within their range" at 120v plus/minus 5% which puts each leg at 126v or 252v for 1phase? Compressors are 208/230 and can't handle that kind of constant power.

Any thoughts are appreciated!

Thx,
Refrigeration nut

Leroy driver

[mgibbs]

246 is fine. I was told on 208/230-240 equipment 197-255 was acceptable. Heck the voltage at my house is 253 and I don't have any problems. Most problems occur from the voltage dropping too low. I'd be more worried if it was 197. Don't think 246 VAC is causing your problems

[LeroyDriver]

Well, they don't make compressors like they did 20yrs ago! Lol built like tanks back in the day. Thanks for the response, I will continue to investigate.

[mark beiser]

In my area, 246 to 252v is the norm.
It falls within the maximum voltage specs of every compressor I've bothered to look at the specs for.
It does give you a little extra capacity over the manufacturers rating.

[refrepairman]

I would not think 246 volts is a problem. It's the norm around here.

[AmadeusMozart]

Nominal voltage in New Zealand is 230V but I have had problems with it going over 254V and equipment failing. The biggest problem however is that the voltage is no longer purely sinusodial due to the switched power supplies to computers, LED and halogen lights, washing machines using DC motors etc etc. If you put an osciloscope then you might well see that the voltage spikes are far higher than that your 246V indicates especially if your voltmeter is not a pure RMS meter. I suspect that it might have to do with insualtion breakdown of the windings. The earlier failing is the same as when you control the speed of a motor with a cheap speed controller, motors will hum and fail earlier.

For computer equipment I use a UPS that first transforms the power and then generates a pure sinusoidial voltage. There are cheaper solutions that stabilise the voltage and transform it in a pure sinus without having a UPS built in. Unfortunately those are not much use if you have trouble with bad brown outs where the mains falls away to very low voltages where a UPS may be required instead. (I recently looked into those because my daughter has trouble with "brown outs" too low voltage when all the hot water cylinders are turned on through ripple control. The computer controlled radio and washing machine were going silly).

[timebuilder]

Nominal voltage in New Zealand is 230V but I have had problems with it going over 254V and equipment failing. The biggest problem however is that the voltage is no longer purely sinusodial due to the switched power supplies to computers, LED and halogen lights, washing machines using DC motors etc etc. If you put an osciloscope then you might well see that the voltage spikes are far higher than that your 246V indicates especially if your voltmeter is not a pure RMS meter. I suspect that it might have to do with insualtion breakdown of the windings. The earlier failing is the same as when you control the speed of a motor with a cheap speed controller, motors will hum and fail earlier.

For computer equipment I use a UPS that first transforms the power and then generates a pure sinusoidial voltage. There are cheaper solutions that stabilise the voltage and transform it in a pure sinus without having a UPS built in. Unfortunately those are not much use if you have trouble with bad brown outs where the mains falls away to very low voltages where a UPS may be required instead. (I recently looked into those because my daughter has trouble with "brown outs" too low voltage when all the hot water cylinders are turned on through ripple control. The computer controlled radio and washing machine were going silly).

I would need to know more about power distribution practices in new Zealand to help you.v

[beenthere]

Well, they don't make compressors like they did 20yrs ago! Lol built like tanks back in the day. Thanks for the response, I will continue to investigate.

How long has each compressor lasted?

246 is fine.

[ryan1088]

How long has each compressor lasted?

246 is fine.

Agreed, time to start looking for a system problem......

[brettrobbins]

Higher voltage within specs on nameplate equal lower amps, which would be better for compressor and electric bill usually lower voltage is what would cause you problems.

[beenthere]

Higher voltage within specs on nameplate equal lower amps, which would be better for compressor and electric bill usually lower voltage is what would cause you problems.

219 volts at 18.26 amps is 4000 watts, 246 volts at 16.26 amps is 4000 watts. So no savings because of the higher voltage and lower amp draw.

[pilotlight]

I remember reading that something like 50 % of all field compressors fail. Due tobad install practices. Maybe that is the problem

On the electric side unless you are getting some really high voltages like 140 on what is suspose to be 125 u will be fine. Like others have said.

Dang old post op probably will not return to this site

[timebuilder]

To anyone with advice,

I've had 2 refrigeration compressors go bad because of too much voltage from panel to condensing unit. Currently 246v. I've solved the problem with a transformer but have this question for all you electricians.

Why does the power company say "they are within their range" at 120v plus/minus 5% which puts each leg at 126v or 252v for 1phase? Compressors are 208/230 and can't handle that kind of constant power.

Any thoughts are appreciated!

Thx,
Refrigeration nut

Leroy driver

There is one standard for the power company, and then there is the voltage standard acceptable to equipment manufacturers. They may be different. Let's start at the beginning.

IF the compressor is actually rated with the 208/230 volt rating (the "slash rating") then you are fine at that 246 voltage. Being 16 volts above 230 should be withing manufacturer's specs. You can ask them to be certain. I would ask.

HOWEVER, if you are using equipment that is rated "208" on the label, you are above the intended voltage rating and in fact are in violation of the NEC.

Does that help?

[captain planet]

Our nominal voltage single phase 50Hz is 230 VAC. 246v is not really much out of spec to be honest. There might be more to the situation, dirty voltage or bad transient voltage problems.

[WyrTwister]

In the USA , 120 VAC devices are actually rated 125 VAC . Same , 240 -> 250 VAC . I gave actually seen 255 VAC . Some of this depends on if you ate close to the " end of the line " or the head of the line " , of a run of primary ?

Some transformers have or had taps , the power company could adjust the secondary voltage , to some extent ?

I have also seen voltage vary with time of day , with load . In the summer , around 05:00 PM , when A/C's get turned to max , electric ranges , washing machines , clothes dryers , water heaters and every thing in the house gets turned on .

God bless
Wyr

[tmittelstaedt]

In the US if you have had to replace equipment due to overvoltage, you can make the power company put a voltage monitor on your line, this is a portable device that records voltage levels for a month or so. This will also record spikes and so on. If an isolation transformer solved it then very likely there's distribution problems. If your in the US and the power company balks then threaten to go to the PUC as all of them are regulated. My father sold high voltage power distribution gear for all his life and quite often power companies find things like failing step down transformers in their distribution systems due to industrial users complaining.

[madhat]

You need to "pay" the the utility to put "their" voltage spike, transient arrestor(s) on your panel(s). I did that years ago after repeated small motor losses, I'm now covered under their insurance. BTW don't expect to make a claim and get paid for damages without this. They have more ways of getting out of paying than a mongoose getting out of a paper bag.

[Ernest Crossman]

I would look at what kind of compressor they were if the voltage was 246 and that killed them. Run all kinds of compressors all day long here on 255.


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[Ernest Crossman]

In the USA , 120 VAC devices are actually rated 125 VAC . Same , 240 -> 250 VAC . I gave actually seen 255 VAC . Some of this depends on if you ate close to the " end of the line " or the head of the line " , of a run of primary ?

Some transformers have or had taps , the power company could adjust the secondary voltage , to some extent ?

I have also seen voltage vary with time of day , with load . In the summer , around 05:00 PM , when A/C's get turned to max , electric ranges , washing machines , clothes dryers , water heaters and every thing in the house gets turned on .

God bless
Wyr

Nearly everything around here is at 255. We are at the head of the grid and that's the usual reading. Anything that says 208-230 runs fine on that. I would look at who installed the equipment or the brand of compressor first. In the summer most things run all day long unless they are well insulated or inside a building. And the extra money to switch to a scroll upon failure is always worth it. I would be more likely to believe something was not done. Like a crankcase heater left out or something before I would blame voltage less than the max I have seen. Even the compressor I just installed on a rare delta three phase system is running fine on 244. What you have to watch for there is it has a wild leg at 214. That will kill refrigerators or anything else if someone that doesn't know installs a circuit in a three phase panel that is single phase. The only place you can be certain it is safe is on leg #1 2 or three are the only legal place to put it but it will be 1 coming in. It took weeks for me to figure out this power system and no one will give me information. It's really frustrating.

[hvacker]

If a compressor fails and the cause isn't found a repeat failure is likely.
Failures are almost always external to the compressor. If possible open the compressor
because often the evidence will be there. I've even opened hermetics at times.

One of the best classes I've gone to was Carrier's tear down school analyze failures.
A voltage problem will be obvious.