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Thread: Checking amps

  1. #1
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    Checking amps

    Sometimes I wonder how accurate a clamp meter is when checking fractional hp motors where amp draws are routinely 1 amp and less. Are my suspicions accurate and if so what would be a better option for checking amperage on things that are say less than 10 amps? My current meter is the 902fc and I do really like it but routinely when Iím checking like a fan motor or whatever and itís rated at for example .8 RLA I can change the the reading to a couple tenths one way or the other just by moving the clamp around the wire,closer or farther away from the the controls. I know being close to the controls can throw one off. So whatís a good one for checking smaller amp draws?

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    Fluke 324 has better resolution for low amperage items. For this reason it is my preferred meter. 325 is good too but has lower accuracy than the 324.

    Place the wire being measured centred and between the lines marked on the jaws for the most accurate measurement.
    Quickly, I must hurry, for there go my people and I am their leader!

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    Wrap the wire around the jaws and divide reading by number of wraps

    Or measure in series with regular dmm

    Unless they are complaining about something not working right I don't sweat it too much. It's the reading give or take a few tenths. Btw I use the 902 as well. I love it!

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    Quote Originally Posted by JayMan7 View Post
    Wrap the wire around the jaws and divide reading by number of wraps

    Or measure in series with regular dmm

    Unless they are complaining about something not working right I don't sweat it too much. It's the reading give or take a few tenths. Btw I use the 902 as well. I love it!

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    Would you consider inline with a brick being more accurate than wrapping the wire around the jaws of a clamp? Sometimes thereís not a lot of slack to be able to wrap. I donít believe ive ever missed any problems because of the slightly less accuracy but kinda like any of us say about doing anything for awhile weíve never had any problems, well that we know of anyway since Even if Iíve never been back to a place doesnít mean somebody else hasnít and found a problem that I missed or caused. If that makes any sense.

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    It truly depends on the meter. I've found that the Amprobe ACD51NAV is very sensitive in the low amp ranges you speak of ie. <1 amp without having to resort to wire wrapping. I use it all the time time to check small blowers and it will even relieably read a light bulb at .12AAC. The Klein CL450 and Amprobe ACD-14-PRO can also do it, and the FP SC440 is ok at it. I can tell you the newer FP X80 series meters CANNOT measure that low at all. Other than that, you're left with more wraps of wire or inline with a DMM. But as mentioned, wrapping can be difficult with the lack of wire in some cases.
    I trust the Amprobe without wrapping so it's in my bag all the time.

  7. #6
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    Many years ago, Amprobe was the standard clamp on meter. It was an analog meter.
    Part of their kit included a multiplier ladder block that had 3 windows for testing small current draw. Good at the time to adjust tstat anticipator (really dates me doesn't it) based on current draw of the gas valve or inducer relay.
    It included a set of leads connected to a female cord end, the block had male prongs to plug in to this or an outlet. The other end had female cord end so you could put a 120 vac corded load thru it. Or they gave you a shorting block for the female end.
    You would use the clip leads for the load and insert the shorting block.
    Unfortunately, the windows in the ladder are too small for for the jaws of newer clamp on meters.
    Probably nothing like this is available anymore because of the sensitivity of newer amp clamps.....most of the time.

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    Quote Originally Posted by Hurst11 View Post
    Would you consider inline with a brick being more accurate than wrapping the wire around the jaws of a clamp? Sometimes thereís not a lot of slack to be able to wrap. I donít believe ive ever missed any problems because of the slightly less accuracy but kinda like any of us say about doing anything for awhile weíve never had any problems, well that we know of anyway since Even if Iíve never been back to a place doesnít mean somebody else hasnít and found a problem that I missed or caused. If that makes any sense.
    Yes there is absolutely no doubt about it. A dmm in series is by far the most reliable method. This is because the meter is looking at voltage drop across a shunt of very precise resistance. This is a much better method than trying to infer current from a magnetic field near other magnetic fields of other wires. That being said clamp meters do a pretty good job and they are usually accurate enough.

    Also with wire wrapping keep in mind that using an alligator clip jumper wire for that is always an option!

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    i use a Fluke i5s amp clamp (with BNC Adapter) and my Fluke 289. the range on the i5s is 10 mA to 5 amps.
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    Quote Originally Posted by jayguy View Post
    i use a Fluke i5s amp clamp (with BNC Adapter) and my Fluke 289. the range on the i5s is 10 mA to 5 amps.
    That is such a sweet setup! But man the cost of that rig is pretty high.

    Are you using it for controls or something that really requires that level of low amp precision? You've made me curious I really love specialized electrical testing equipment!

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    I think Iíll have to pick up a fluke 116 or maybe the Klein mm700 I think is the model of it as a companion to my 902. Those meters also have a bigger ohms scale than my 902fc has so thatís always a plus as well.

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    Quote Originally Posted by Hurst11 View Post
    I think Iíll have to pick up a fluke 116 or maybe the Klein mm700 I think is the model of it as a companion to my 902. Those meters also have a bigger ohms scale than my 902fc has so thatís always a plus as well.
    Does the 116 have lowz mode? The 117 does and that's what I would recommend!

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    Quote Originally Posted by JayMan7 View Post
    Does the 116 have lowz mode? The 117 does and that's what I would recommend!

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    I forget what lowz mode is. The 116 is their so called hvac meter so I believe it has has a couple things thatís better for us over the 117, am I correct in thinking that or does having the 902 kinda make up the difference between the two?

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    Quote Originally Posted by Hurst11 View Post
    I forget what lowz mode is. The 116 is their so called hvac meter so I believe it has has a couple things thatís better for us over the 117, am I correct in thinking that or does having the 902 kinda make up the difference between the two?
    Okay I just looked it up. Definitely do not get the 116. It only does microamps. Your 902 will do that. So you want the 117 that does up to 10 amps. I think both meters have the lowz mode and what that is is a low impedance mode which changes the impedance of the multimeter to like 3000 ohms. This puts a slight load on the circuit and will eliminate ghost voltage from readings. It is also an auto ranging and auto voltage mode so it automatically switches from AC to DC which is handy for troubleshooting generators.

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    Quote Originally Posted by JayMan7 View Post
    Okay I just looked it up. Definitely do not get the 116. It only does microamps. Your 902 will do that. So you want the 117 that does up to 10 amps. I think both meters have the lowz mode and what that is is a low impedance mode which changes the impedance of the multimeter to like 3000 ohms. This puts a slight load on the circuit and will eliminate ghost voltage from readings. It is also an auto ranging and auto voltage mode so it automatically switches from AC to DC which is handy for troubleshooting generators.

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    Thatís right I got the 116 mixed with something else. Cooke months back I was looking at meters and now have em all screwed up. Definitely donít want the 116 since it canít check amps like we need to.

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  17. #15
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    Here is my solution for anything that is connected with 1/4" spade terminals.
    The end you cant see is the male terminal.

    Sent from the Okie state usin Tapatalk

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  19. #16
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    It is 10 wraps of 14 guage THHN with male and female terminals for connecting in line with blowers and fans.

    Sent from the Okie state usin Tapatalk

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    Quote Originally Posted by R600a View Post
    It is 10 wraps of 14 guage THHN with male and female terminals for connecting in line with blowers and fans.

    Sent from the Okie state usin Tapatalk
    Very nice I like it!!!

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  21. #18
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    Quote Originally Posted by R600a View Post
    It is 10 wraps of 14 guage THHN with male and female terminals for connecting in line with blowers and fans.

    Sent from the Okie state usin Tapatalk
    Definitely awesome idea and being 14 gauge itíll handle whatever load you wanna use it for and if itís not big enough, then itís not needed anyway.

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  23. #19
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    Quote Originally Posted by Hurst11 View Post
    Definitely awesome idea and being 14 gauge itíll handle whatever load you wanna use it for and if itís not big enough, then itís not needed anyway.
    I've been meaning to make that for a few months but I just never seem to have the time so I saw when you posted that thread and in between jobs I made it today.

    Sent from the Okie state usin Tapatalk

  24. #20
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    Oh by the way i named it the amp-lificationator. (Insert maniacal laugh here.) Yep I have been watching too much Phineas and Ferb with my kids.

    Sent from the Okie state usin Tapatalk

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