amp draw meter

[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.