500mF (mF = millifarad)is one half of a farad.
or do you mean uf;microfarad? milliF caps are rare.
OTOH,"MF",capital M,is MegaFarad.
M = mega,m = milli,mmF = microfarads(uF) in the old notation.
there are polarized electrtolytics(leads marked +/-) and non-polarized
caps(electrolytics are marked NP,non-electrolytic caps are not marked).
both are used in all sorts of electronics.
then there are caps that can handle higher currents,those are the sort used
in motor circuits.
On Fri, 27 Jan 2012 20:14:39 -0800 (PST), Bob_Villa
I have noticed some things on power poles that look like pole
transformers without any secondaries and they are smaller. The HV line
just enters and exists then midway to a farm or industrial complex.
Maybe those are the caps. I never understood their purpose.
Besides industry, large farms have lots of power hungry motors. I just
operate a small farm, but even I have hay elevators and augers and other
devices with fairly large 110 or 220 volt motors.
Also, in reply to others speaking in electronics terms I am familiar
with non polarized as well as electrolytic caps. I worked on a lot of
electronics when I was a kid. Mostly tube stuff back then, and back
then, mf meant micro-farad, and mmf meant miro-micro-farad. Oddly
enough they were also called condensors in those days. I still fart
around with a few home repairs of electronic stuff, but these days
finding parts is a challenge, if not impossible. Especially ICs. That
takes the fun out of it.
On 1/28/2012 4:08 AM, email@example.com wrote:
If they are wired in series on the distribution wiring they are
is a not-great description.
They take the place of a fuse, and are always downstream from a
recloser. Reclosers are also wired in series, but are much larger.
PF correction caps are wired phase-to-phase.
There are polarized, back to back polarized caps used for ac, like in
speaker crossover networks and other things. Most caps used in electronics
are ac or dc, meaning non polarized, except some non polarized have mark to
indicate outer foil.
The others are polarized because they have a liquid filling to obtain high
Dc is typically more dangerous. I still remember grabbing hold of a high
current 500 vdc source in my ham transmitter. I also remember sticking my
finger in the antenna socket of my spark gap transmitter, of a toy bus I
had when young.
My mother told me of the day I was pouring water into a lamp socket, and i
said it made a funny noise.
I got a kick out of feeding either AC or reverse DC into a small
electrolytic capacitor. Something less than an inch long will go off like a
firecracker and the metal covering will fly across the room. In those days,
I had lots of used capacitors stripped off old electronic (nixie tube type)
Reminds me of the time I brought the little kid out of my boss. I had
him hooking up small electrolytic caps to 120VAC via an extension cord
and out a door. We kept increasing the size and it didn't take too long
before they didn't explode, they just tripped the 20amp breaker. Never
forget when he told me "what ever you do, don't tell my wife!".
Heh, we used to do that too at school in the electronics lab - 240VAC
would make them go bang quite nicely.
I love Nixie stuff. I had a big old calculator (IME 86) with a Nixie
display for a while, but didn't keep it when I move to the US (decided it
was too heavy to ship). Hopefully at some point I'll find something
similar this side of the Atlantic!
I did pull some Nixies from some old grain analysis equipment, which will
probably end up as a clock display one day (possibly one based on neon
Yeah, I've still got an old nixie calculator that I use in my workshop. It
is big and heavy enough that it doesn't get lost, and it works no matter how
much sawdust accumulates on it. Believe it or not, it was made by Sony. Some
of the display tubes are getting a little weak.
And most people would be wrong. The person in the tub would have to be
touching the toaster, or whatever, thrown in the tub. Even then, if the
internals of the appliance didn't fry, the circuit breaker would trip. At
most, if touching the device, the bather would experience maybe a
quarter-second of jolt.
Early 80's? That's around the time a good friend of ours died from a
hair dryer in the tub, maybe as late a 1986. The breaker didn't trip,
and of course that was before widespread use of GFCIs.
The body is basically a sack of salt water. It probably conducts
better than the bathwater. I'm sure the plumbing as well as the
fixtures was metallic. I don't know what would happen today when both
drain and supply lines are likely to be plastic.
While you might say they charge with DC only, a capacitor will charge on an
AC circuit. It depends on where in the cycle the capacitor is removed. It
can be charged anywhere from 0 to the maximum peak line voltage. It is
being charged and discharged 120 times a second for standard house current
in the USA. Half the time one plate will be positive with respect to the
other and half it will be negative.
When saying AC or DC capacitors, that is very misleading. The polarized and
nonpolarized is more correct.
Connect and disconnect a motor starting capacitor enough times and it will
have a charge stored in it during one of the times.
You are going to bet your life on that untruth / half truth.
Pure water containing no ions is an excellent insulator, but not even
"deionized" water is completely free of ions. Water undergoes
auto-ionization in the liquid state. Further, because water is such a
good solvent, it almost always has some solute dissolved in it, most
frequently a salt. If water has even a tiny amount of such an
impurity, then it can conduct electricity readily, as impurities such
as salt separate into free ions in aqueous solution by which an
electric current can flow
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