220 V table saws and ground

[Larry Jaques]

On Tue, 08 Dec 2009 13:36:58 -0600, the infamous dpb scrawled the following:

That's true. Local companies adjust transformers so the voltage at most outlets is going to be that nominal 120v. If you have a lot of heavy users on your particular transformer, the normal voltage will run high to compensate during those times the heavy users are using heavily. Capice?

-- To know what you prefer instead of humbly saying Amen to what the world tells you you ought to prefer, is to have kept your soul alive. -- Robert Louis Stevenson

[Larry Jaques]

On Tue, 8 Dec 2009 14:08:38 -0800, the infamous "Nonny" scrawled the following:

I had K&T in my old 1939 house in Vista, CA. When I rmodeled the front bathroom, the tubafores behind that 1/4" plywood all measured exactly 2" by 4", in roughsawn redwood, too.

I hated wiring anything extra into that home...

-- To know what you prefer instead of humbly saying Amen to what the world tells you you ought to prefer, is to have kept your soul alive. -- Robert Louis Stevenson

[Lew Hodgett]

=============================== Shades of my youth.

A 100W light bulb hanging in the pump house is your friend in winter.

Also works when hanging beside the engine block.

Had a shallow well pump in a pit covered with a lift off, tar paper covered wooden roof.

First year the pump froze when it got cold.

After that, it was a light bulb in the pit and straw bales over the roof.

Problem solved.

Today, heat tapes are safer and more efficient.

Lew

[Swingman]

Not necessarily so. AAMOF, I'm fairly certain that Leon's electrical service entrance is grounded as per code, considering where he lives.

From his description the problem he was experiencing is typically a problem with the center tap connection on the secondary side of the service transformer, and should have nothing to do with whether his electric service entrance was grounded.

I saw this exact same scenario just recently when a new service transformer was improperly installed that was serving the area I was building in, and had just that day passed a rigorous final electrical inspection, including, of course, the proper grounding of the electrical service entrance.

[Leon]

No, we all have grounding rods, the power co. guy checked mine. But he did say if it has to handle the whole house because of a bad common and is not a really really good ground you will see lights dim.

[Swingman]

I bet that ground rod connection is now "gut'n tight", if it wasn't before! :)

[Bob La Londe]

That would be very unusual. You do not need a neutral for 220, but you should have a ground for safety.

[CW]

Nope. The transformers at the substation have tap changers (works like a voltage regulator) to maintain the voltage as close as possible under varying load. As there are a finite number of taps, the voltage my vary a bit.

[basilisk]

I wire two rubber sockets in series and use 200 watt bulbs, same amount of heat and the bulbs last a couple of seasons.

basilisk

[Larry Jaques]

On Wed, 9 Dec 2009 17:05:02 -0600, the infamous "Leon" scrawled the following:

You must live in a dry area. Grounding is less certain there.

-- To know what you prefer instead of humbly saying Amen to what the world tells you you ought to prefer, is to have kept your soul alive. -- Robert Louis Stevenson

[Larry Jaques]

On Wed, 9 Dec 2009 21:00:48 -0800, the infamous "CW" scrawled the following:

That's pretty much what I said in different words, CW, unless these are automated switches, which leaves us in -exactly- the same situation I just described. ;)

-- To know what you prefer instead of humbly saying Amen to what the world tells you you ought to prefer, is to have kept your soul alive. -- Robert Louis Stevenson

[Robert Bonomi]

In article , CW wrote:

A *BIT* ???

In many places, the regulation is *terrible*. One place I lived, I was across the parking-lot from the neighborhood substation, in a building with _old_ wiring in it ( turning on some of the big tube-type electronic test gear I had would cause a _10+_ V drop in the voltage at that wall outlet. [no drop on a different circuit, that was ALL losses in the building wiring -- eek!]) I had a lab-grade line voltage monitor plugged in on one circuit, and could watch the voltage drop as the neighborhood 'powered' up in the morning. Around 3 AM 'line voltage' was circa 127-128v by 10 AM it was down around 112-113 V. This was _after_ I'd had a 'discussion' with the electric utility, resulting in a couple of real engineer (MSEE and better) types, not just a 'lineman', coming by to visit, and check out my monitoring gear; because when I first called the utility, peak sustained voltages were in the 132-133V range -- which played hob with the life of the light bulbs. :-/ They came out prepared to dismiss the crank reporting; recognized some gear that was was in their labs, and decided to take me seriously. A quick check comparing what my box displayed against their 'calibrated' box -- in agreement to within 0.1V -- and they promptly a greed that there was a significant problem. A little _manual_ transformer tweaking got things to 'borderline acceptable' at my location. *THEN* they started looking at what was necessary to 'fix it right' for the whole area.

[Lew Hodgett]

The utility is only required to provide 120V, + 10%, - 15%.

IOW, 132V Max, 102V Min.

Multiples of 120 apply (208, 240, 277 & 480).

Which is why the utilities get away with supplying "brown out" power levels during periods of peak demand.

Over voltage problems are a little more difficult to catch since shortened life requires some period of time to document.

Lew

[CW]

Which they are. It would be quite the waste of manpower to have someone reading a meter and changing taps 24 hours a day.

[dpb]

Robert Bonomi wrote: ...

I only buy 130V bulbs for that reason...and in fact, the door handout "goodie bag" at annual meeting always has at least one bulb in it and _they're_ 130V-rated, too.... :)

--

[Lew Hodgett]

That is actually false economy.

Yes, you get longer lamp life which is good; hovever, you also get reduced lumen/watt output which is bad.

You are buying lumens, not hours of lamp life, so it becomes a trade off of economy vs convenience.

Lew

[keithw86]

In the US it's +/- 5%, ie. 114V to 126V.

They "get away" with it because there is no other choice, other than to shed customers.

[dpb]

Lew Hodgett wrote: ...

No, I'm buying bulbs...or actually, not buying nearly as many bulbs as would otherwise.

They output what they output (which if blown is nothing, nil, nada, until replaced). _That's_ the tradeoff.

[Lew Hodgett]

Maybe that's in your utility area, but not the last two utilities areas I've had.

Lew

[Lew Hodgett]

Actually you are buying both lamps and KWH to operate them.

If you wish to buy more KWH than are needed for the sake of convenience, that's your choice.

Lew