Tony Hwang wrote:
bud-- wrote:
Kevin Ricks wrote:

wrote:

What's a low-cost way to add a meter to an 110V electrical circuit?
This circuit runs from my service panel to our well pump. I want to
know how much electricity the well pump uses. Are there replacement
circuit breaker blocks that have meter functionality built into
them? ...or would a vampire a meter onto the circuit cable so that
it's sitting on the circuit between the service panel and the pump?
If so, what product? Is this something I can do myself? (I'm
comfortable wiring light fixtures, outlets, switches, etc.)

I know there are neat meters for $100 that plug into a standard
household outlet and then you plug your device into the meter and it
meters and compiles data until you reset it. Then you plug the meter
into a USB connection on your computer and dump the data into a
software that comes with the meter. ...but again all I have to work
with is a service panel, a pump, and a circuit that connects them, so
there is no outlet to plug into.

And by the way, I know the amount of electricity the pump uses is
negligible, and I'm not concerned about the cost of the electricity.
It's mostly an academic exercise. I'm just curious how much juice the
pump uses because on one has been able to tell me. It would be
interesting to know.

Please advise.


Not clear if you are wanting a data logging meter or not?

If not use a clamp on AC amp meter?
http://www.harborfreight.com/cpi/cta...emnumber=96308

The above is probably not the most accurate but probably ball park -
it's cheap.
If you want a better clamp on then get a true RMS meter like a Fluke
but then you are up around $100.
You will have to open up the panel cover to take a reading or find a
place anywhere along the pump wires were you can separate the hot
from the neutral enough to get the clamp over a single wire.


Depends on if the OP wants an accurate value for power.

A clamp on ammeter will give you the amps, but not the watts. The
difference is power factor. Some of the current is "reactive" and part
of the cycle creates the magnetic field, part of the cycle the
magnetic field collapses and current is returned to the utility.

The nameplate current rating has the same problem. In addition the
nameplate current is maximum value. The actual current depends on
factors like head pressure at the pump.

The OP could google for "submetering". Or if the voltage is 110 and
the current is reasonable modify the circuit to use a plug-in meter as
some have suggested. There are clamp-on watt meters but all I have
seen are expensive.

Hmmm,
There are digital true RMS reading clamp on meters for pretty reasonable
price. I have one with dual display which read current and vltage
simutaneously.
..
Thats good if the OP is satisfied with current.

But if you actually want watts you need to know the phase angle between
the voltage and current.

--
bud--