Think 240 volts coming from a center tapped transformer. Across the two
hot wires is 240 volts. From either hot wire to the center tap is 120
volts. Most codes in US require the center tap (which is called
neutral) to be bonded to ground at the service panel entering the
residence. It is still single phase. Actual two-phase service was an
entirely different animal way back in the past history of Alternating
Current, and is not found outside of a very few museums that show how it
On Sat, 03 Nov 2007 14:22:05 -0500, Tom Veatch wrote:
When I converted my lathe to 220v, I plugged in the light and my drills to the
same power strip that the lathe used to be plugged into.. Just lazy, I guess..
Please remove splinters before emailing
Couldn't a guy just stick a one or two amp 400PRV diode in series with
the hot lamp lead? That way you'd get only half of the sine wave. I
seem to remember that "they" used to sell a diode packaged so it would
drop into the light socket "to make your bulbs last forever".
Tom Veatch wrote:
They are available.
A little story.
American Shipbuilding in Lorain, Oh, would run bare stringer lights down
thru the ship they were working on for light.
To keep the theft to a minimum, they used 240V, incandescent lamps, which
totally pissed off the workers so as a diversion, they would throw stones at
the lamps to break them during lunch hour.
Had at least 2 guys whose job was to replace broken lamps on a full time
A/S/B had a contract with my distributor to buy at least 25,000 lamps/year
American Ship Building was closed years ago by owner George Steinbrenner as
a result of a labor dispute.
The reason I brought up the tiny voltages and autoranging is simply
because I've seen it many times on unpowered (breaker open) circuits.
** http://www.bburke.com/woodworking.html **
On Sat, 03 Nov 2007 22:08:28 GMT, email@example.com (Doug Miller) wrote:
Or, in the case of my last couple of houses, are the breakerS on...
The dryer circuit in my garage in the States has TWO 40 amp breakers ganged with
a bar on the switch end of the breaker, but the older house had 2 breakers that
weren't ganged... I guess you could only throw one breaker and have one 110v leg
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A series circuit would produce 120 volts from the leg to ground.
To check for a true reading of 240 volts, you need to test from leg to
leg. For 220 or 240, a test from the leg to ground can float a variable
reading. Also a loose neutral wire can produce a low voltage from leg to
ground. This is why we are to read from leg to leg on a 240 volt
circuit, this is the true voltage.
in my experience, this can happen when the either the neutral wire in a
120 volt circuit or the 2nd leg of a 240 volt circuit is missing. If
so, you'd probably get the same result if you didn't stick the neutral
probe of the meter into the receptacle at all. Personally, I use a
simple neon tester to figure these things out so I don't get confused by
a digital meter.
That's why I asked the question I did.
If he using a panel/sub panel that will take 1/2 height breakers, he may not
be spanning both _legs_ with the 220 c'brk. IME, the 'position of the
circuit breaker is important/necessary in these type panels when installing
A WAG, but the fact the he took the time to use a voltage meter indicates to
me that he tried to plug something into the receptacle and it didn't work,
so out came voltage tester. The above scenario is not uncommon, even among
some electricians I know.
It does make sense that if you split 220-240VAC in series you'll get
50-60VAC on each one. I'm guessing since you haven't mentioned blowing
a breaker there isn't a direct short or shunt someplace.
Is the end of the circuit terminated correctly??
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