How to add a meter to a circuit?

[JohnnieMarr]

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.

[Robert Allison]

I haven't seen many well pumps that are 110 volt, but if you have one, just install an outlet between the breaker for the pump and the wire to the pump. Then install a plug on the wire. Then buy one of these:

Insert your energy cost per kw and it will give you either the wattage used, or the dollar amount for that wattage. No need for a computer.

If your pump is indeed 220, then I don't know of a meter like this for 220. You could install a meter loop in the line at the pumphouse and have a standard meter installed and read that, though. That is not that expensive. However, this could be a problem. With all the meter loops that I have used, I have supplied the base and the electric company supplies the meter itself. You may be able to find a used temporary loop for sale, but the meter will most likely belong to the Electric Utility. If you call the utility and ask them, they may provide you with one or tell you what you need to do to get your well pump metered separately.

[Kevin Ricks]

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

If not use a clamp on AC amp meter?

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.

Kevin

[Speedy Jim]

Let's assume the pump is indeed 110V. Jury rig a recept to the pump wires. Plug in an old-time analog clock. The clock will record the hours of use during 24 hrs, for example.

Get the pump Amps or assume some figure for the experiment. mult X 110V = watts (approx.)

Pump use may not be trivial; a lot depends...

(If the pump turns out to be 240V instead, connect the clock from one side to Neutral.) If you're not versed in how-to-do stuff like this, then don't. Disclaimer required by Usenet lawyers...

[Howard]

There are a number of companies on the web that sell real meters just LIKE what the electric utility would use. As you said you also need a compatible meter base and need to wire it. That is generally called submetering. There are few companies that make and sell solid state type devices to perform the metering function.

I know of no electric utility that loans or provides its meter for submetering or other purposes. Generally they a don't do this because the utility should be tracking their meters carefully. Meters are the utility's cash registers. Once a utility company's meter gets out of their hands, then it makes it easier for an energy thief to steal energy because he would be using an "official" meter (logo, etc.) that might not be spotted by a meter reader or other person. There are other technical ways to track and find missing meters and also how not to find them.

[Anonymous]

Get a cheap ( analog ) bedside clock. Set it to 12 o clock. Connect it so the clock runs when the pump runs.

At the end of a week ( or a month ) the clock will represent the number of hours/minutes the pump has run.

Multiply watts ( on the motor plate ) times hours ( on the clock ) to get watt-hours.....

[Tony Hwang]

Hi, If the clock ran more than 12 hours, then what? There is a meter which count by the hour and it's fraction.

[Terry]

Check it every day or get one with a month day display.

It sounds like a pretty slick idea IMO.

If it runs more than 12 hours per day you should be able to see that without the clock.

[Bob]

Does anyone still make ordinary mechanical AC-only clocks anymore? You can spend more money and get an industrial timer, though.

[bud--]

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.

[Tony Hwang]

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.

[bud--]

. 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.

[Jimmie D]

Install a run time meter on your pump, borrow or rent an ammeter to measre the current and calculate the power used.

Jimmie