amp draw meter

[eugene thomas]

not sure if labeled wright but what looking for is tool that could measure amp draw for shop as use different tools. i have 200 amp meter that powers house and shop and not want to be running tools and have the misses turn on oven and lights dim.... looking for budget friendly option.

[Malcolm McLeod]

Maybe like this ...?? https://shop.emporiaenergy.com/products/gen-2-emporia-vue-whole-home-energy-monitor?variant=36230623363231&currency=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gclid=EAIaIQobChMIguj67uqU7wIVUeDACh2CkwlBEAQYBSAB EgK2wfD_BwE

No experience with it.

[George Yetka]

Malcolm I believe that measures KW usage. A clamp meter can show you amp usage while the tool is running but you would need to clamp each hot lead that goes to any particular tool. If you have a sub panel this would be easier.

The easier thing to do is calculate all major draws in the house based on equipment rating for running amps and estimate the smaller stuff add that all up and figure out what worst case draw on the house would be and figure out from there what worst case in the shop would be(compressor/dust collector/table saw/lighting)


Adding those together you should be safe.

Worst case would be if you had electric (dryer/stove/electric heat).

[Ken Combs]

search for 'clamp on ammeter'. There are many choices, 15-$big, depending on your needs.

Caveat, for your intended use, the labeled specs on tools and motors will provide enough accuracy. Just allow for a current surge when motors start.

[Malcolm McLeod]

Malcolm I believe that measures KW usage. ....

You may be right; I should have looked closer. I saw the CTs 'Amp' ratings and just assumed.... silly me.
(Also seems silly the supplier would not give you a way to see the amps?)

[George Yetka]

You may be right; I should have looked closer. I saw the CTs 'Amp' ratings and just assumed.... silly me.
(Also seems silly the supplier would not give you a way to see the amps?)


I think the idea of that device is to monitor your money going down the drain amp draw isnt as important in that regard

[Doug Dawson]

not sure if labeled wright but what looking for is tool that could measure amp draw for shop as use different tools. i have 200 amp meter that powers house and shop and not want to be running tools and have the misses turn on oven and lights dim.... looking for budget friendly option.
You would use a clamping multimeter. You need to have access to the individual wires. For 120v you could use a splitter like this:
https://www.amazon.com/gp/product/B001DPR0FE/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
For 240v you could cut a length of heavy duty extension cord, attach male and female plugs on the ends, and split it partially along its length to have access to the individual wires, carefully clamping on one of them (before powering it up.)
That’s safer than opening up the panel.

[Frank Pratt]

I bought a donut CT & digital display for my DC that was shockingly inexpensive and quite accurate. You'd need 2, 1 for each line. I think it was from Amazon, or maybe ebay.

[John K Jordan]

I use a clamp-on amp meter. If not familiar, these are actually "clamp around" meters. I clamp around the individual conductors at the breaker. Don't clamp around a cable (such as Romex) with more than one conductor.

Since it is sometimes difficult to get the fat clamp around a conductor in a tight spot, Klein, Fluke and probably others sell a clamp meter with a flexible probe. I want one.

https://www.homedepot.com/p/Klein-Tools-Flexible-AC-Current-Clamp-Meter-CL150/305221468

JKJ

[Mike Henderson]

Unless you're running some really big stuff, a 200 amp service should be plenty. I have 50 amps to my shop (subpanel) and never tripped the breaker. I doubt if I ever get close to 50 amps.

I have the usual 240 volt tools - jointer, table saw, dust collection, bandsaw. The bandsaw requires a 30 amp circuit but I doubt if I ever draw close to that. All the other tools are on 20 amp circuits.

Mike

[Bruce Wrenn]

Unless you're running some really big stuff, a 200 amp service should be plenty. I have 50 amps to my shop (subpanel) and never tripped the breaker. I doubt if I ever get close to 50 amps.

I have the usual 240 volt tools - jointer, table saw, dust collection, bandsaw. The bandsaw requires a 30 amp circuit but I doubt if I ever draw close to that. All the other tools are on 20 amp circuits.

Mike


I have a 70 amp sub panel in my shop. All the usual suspect tools, plus both a stick and MIG welder. Never lacked for power. Own a HF clamp on amp meter. Works for everything I need.

[Brice Rogers]

I have a clamp on ammeter too. I made a special cable to make it easy to use without needing to open up the panel. The cable consists of a receptacle and a line cord where the individual conductors at the receptacle end are available to be individually clamped. So, if I want to measure the current that something is drawing, I just plug the cable in to the wall receptacle and plug the tool into the adapter cable.

[Doug Dawson]

Unless you're running some really big stuff, a 200 amp service should be plenty. I have 50 amps to my shop (subpanel) and never tripped the breaker. I doubt if I ever get close to 50 amps.

I have the usual 240 volt tools - jointer, table saw, dust collection, bandsaw. The bandsaw requires a 30 amp circuit but I doubt if I ever draw close to that. All the other tools are on 20 amp circuits.
Adding a 50amp circuit to your sub panel so you can charge an electric car (as many of us will sometime over the next decade) really changes things. I would put a 100amp sub panel as the future proof minimum these days. Of course, if your cars never go anywhere near your “shop”, that might be different. ;^)

[Bill Dufour]

If you use a clamp on meter around two wires, like a power cord, it will read zero amps ac or dc. This is because equal amps are flowing in opposite directions, so net zero flow. You have to make an extension cord that separate power wires are clamped individually. The old dumb power meter indicated power draw by the rpm of the spinning disk.
the new smart meters show nothing at all except total usage over time in units too large to be useful. Our utility dumbs down the meter so no information is shown. My mothers showed voltage hz etc. I guess it confused the local idiots so they dropped it.
BillD

[Mike Henderson]

Adding a 50amp circuit to your sub panel so you can charge an electric car (as many of us will sometime over the next decade) really changes things. I would put a 100amp sub panel as the future proof minimum these days. Of course, if your cars never go anywhere near your “shop”, that might be different. ;^)

Just recently, I put in a second subpanel for electric car charging. That one is 100 amps. So I have a 50 amp subpanel for the shop and a 100 amp subpanel for EV charging.

Remember that an EV will only draw 80% of the circuit current - at max. So the most your car will draw on a 50 amp circuit is 40 amps. Some cars, such as the Tesla Model 3 and Y, will only draw 30 amps on a 50 amp circuit. That's because of a limitation on the charging circuit in the car.

When you plug an EV into a 15 amp 120 volt circuit, it will only draw 12 amps. Takes a loooong time to charge an EV at 12 amps, 120 volts. The Superchargers operate at 440 volts (if I remember correctly). They're planning for long haul trucks to be electric. Those will have to draw some really big power from the charger to charge up the batteries in a reasonable time.

Mike

[I checked and the voltage on the SuperCharger is 480 volts. See here. (https://en.wikipedia.org/wiki/Tesla_Supercharger)]

[Bill Dufour]

Frito Lay here has some Tesla Semitrucks delivering chips. I understand their Megacharger is about one megawatt. At 240 volts that would be 4167 amps! I would hate to wrestle with the charging cord that can handle those amps. I am sure they use more voltage to reduce the amps. But probably not more then 600 volts or so.
Bil lD

[Jack Frederick]

I have a 200 amp service with 100 amp panel at the house and 100 at the shop. Being a hobbyist I use, usually two machines at once. The DC and whatever machine I am running. I have a 50 amp circuit for my welding machine. I doubt that you will have a problem, but a good clamp on is a good tool. I have Fluke and UEI.

[Steve Demuth]

Malcolm I believe that measures KW usage. A clamp meter can show you amp usage while the tool is running but you would need to clamp each hot lead that goes to any particular tool. If you have a sub panel this would be easier.

The easier thing to do is calculate all major draws in the house based on equipment rating for running amps and estimate the smaller stuff add that all up and figure out what worst case draw on the house would be and figure out from there what worst case in the shop would be(compressor/dust collector/table saw/lighting)


Adding those together you should be safe.

Worst case would be if you had electric (dryer/stove/electric heat).

Given the way the device is installed, it's clearly measuring amps and displaying kw. The conversion is trivial. At 120 v, 1kw = 8.3Amps.

[Bruce King]

Harbor fright and N. Tool has the clamp on type that works well. About $20.


not sure if labeled wright but what looking for is tool that could measure amp draw for shop as use different tools. i have 200 amp meter that powers house and shop and not want to be running tools and have the misses turn on oven and lights dim.... looking for budget friendly option.

[Tom Bender]

Malcolm I think you have found the right tool for Eugene. It takes a little installation and it may not fit into a main panel so there's that. Nut it will provide the info needed to see in the shop and in the kitchen if it's ok to turn something on. There's still the risk of both hitting the switch at the same time. It would provide a lot of fun and slightly useful data too. If anyone could share this kind of data we'd all be interested.

So does Eugene need this? 200 amps is quite a lot of power for a residence. But a house with electric resistance heat, an electric clothes dryer, an electric oven, and electric water heater, an electric car charger and a hungry shop could test it.

[Alex Zeller]

You could do the simple thing and just add up the numbers on the breakers. Figure out which tools are going to be running at the same time, like a dust collector and planer and then add up the breakers. This will give you the maximum they can draw. Add that to things like a range or drier circuits and if they are all well below 200 amps you're not going to have a problem and don't need to figure out actual amperage the tools are using.

For me the range is 50 amps, the drier is 30, the well pump is 30, the dust collector is 30, and the planer is 40. I'll never used the welder (50 amps), or any of the other woodworking equipment at the same time. So adding everything up and I get 180 amps maximum from major stuff. Of course there's always other stuff drawing power but nothing that's going to equal another 20 amps. Remember, this is maximum load, not actual load which will be less. So there's not much reason for me to even bother to go through the effort of trying to figure out how much power they are actually drawing.

Then you have to realize that a motor is going to draw the most power when it starts up (depending on load) and then when being pushed to it's limits. For example a 20" planer is going to draw more power planing a 20" board at the maximum it can remove in a single pass vs a 6" board. Measuring the current draw when it's on but not actually planing a board really doesn't tell you a thing. To use a clamp meter successfully you really need to have a multi-meter that has a peak hold function so it can record the highest amount.

[Tom Bender]

200 amp service means 200 amps at 240 volts. You will need to add the amps connected to 240 volts plus 1/2 of the amps connected to 120 volts.