265 volts supplying house.

[wideawake]

the max for our units is 253 volts.what cautions should i tell my customer on his new purchase of 2 lennox variable speed heat pumps?i have already told him to call the power company,but i could use more ammo to convince him.he seemed like he was going to bluff me off even after i told him it could void his warranty.this man has money and doesnt worry a about sh!t.I probaly wouldnt worry about it too much if it wasnt me that busted my ass installing a damn good job.i like to see my jobs work for 20 years.

[rmeader45]

Are you a Lennox dealer? If so just make mention of the voltages on your service invoice, have the H/O sign and when there is a problem down the road let Lennox address it.

[tinmantu]

Not saying this is what is happening with you, but I had a couple of tripped breaker calls after a lightning storm early this summer and checked voltage at panels of both houses and was getting 260 volt readings...I called the electric company myself and asked them to check it out...turned out that my digital voltmeter had a low battery..they guy from the electric company said it happens all the time with digitals when they get low...new battery and sure enough, I was reading the same as him...all was fine.

[wideawake]

trust me ive been there and done that when it comes to a low battery meter,but i checked with 2 fluke meters and my helpers uei meter.also we are a lennox dealer.

[Jultzya]

Originally posted by tinmantu
turned out that my digital voltmeter

Must have been a UEI. :D

[joey791]

Variable speed? Not only bring up the point about being out of spec but Im sure the electronic boards wont like it too much either.

[drfluke]

I've seen old delta transformers still in service.Tap the Wrong leg to the service can give this kind of voltage.give them a call and I'll bet the power company will get there pronto.If home owner won't call I sure would. It's their resposibility to deliver proper power.( At least in Tenn.) and you'll be the Hero.

[cem-bsee]

EVERYTHING in that house is at risk!!

[spotts]

"But I have the fastest dryer in town........"

[sirwired]

While the motors and heating elements in his house won't be too happy, actually his electronics are the least he has to worry about. The vast majority of modern electronics use switching power supplies. These are extremely tolerant of out-of-spec voltages, so they should be fine. The only electronics I know of that use old-fashioned transformers to do anything interesting are CRT's (Televisions, computer monitors). Also, REALLY cheap AC/DC adaptors might also have a problem, but these are not particularly common.

SirWired

[cem-bsee]

so, just what are the specs for "switching" power supplies?
re: incoming voltage --

[pecmsg]

Wideawake
Call the electrical supply company yourself. Make them aware of the problem. It wont cost you anything and may save a lot of headaches down the road.

[wideawake]

thanks for the info everybody,i calling tomorrow and im going to be done with this.

[sirwired]

cem,

While of course every supply is different, just looking at my laptop power "brick", it is spec'd for anything from 100V-240V. It would likely work just fine even in excess of that. I suspect for safety reasons you wouldn't want to run continuously in an overvolt condition, but the supply itself shouldn't care.

Power supplies for desktop computers usually require the flipping of a switch, but operate on much the same principles.

A switching power supply has several advantages:
1) Smaller and lighter.
2) Wide range of input voltages without burning up a poor overworked voltage regulator.
3) One supply can produce multiple outputs without too much additional circuity. (A modern computer supply produces five different voltages.)
4) More stable output.

Disadvantages:
1) Relatively low max output current. (Compared to what you could produce with a transformer and bridge rectifier.)
2) More complicated. (I can build a transformer-based 5V supply with four parts. A switching supply takes far more.)
3) DC output only.

SirWired

P.S. This is all dimly rememberd from my decidedly least favorite classes, anybody is free to correct me and let me know how badly I should have flunked.

[gus99]

I must disagree with your disadvantage #1. Switching power supplies are capable of very high currents. The power supply in a typical PC supplies 3.3 volts at 40 amps along with 5 volts at 20 amps, plus 12 volts a several amps. Now you know how big a PC supply is. How big would a linear 60hz transformer supply be to produce the same wattage? At least as large as two PCs!

Also look over on the commercial forum. How about those variable speed drives on 2000 ton chillers. Well they are also a form of switching power suppply.