# Amperage At Overload High



## Mikester1 (Jul 28, 2011)

I am working on a 480 volt motor that at the load side of the overload it is higher than at the MDP, which is about 50ft. away. Am I missing something here? I am thinking it would be just the opposite. Higher at the MDP and lower at the overload block with resistance of the wire and length of run, ambient temp...not the the other way around. I'm talking almost 10 amps of difference. What is this?:blink:


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## Big John (May 23, 2010)

With no failures in the circuit, current should be the same at any point on the wire. Voltage is consumed, current is not.

Something is causing your meter to read inaccurately. Try a different one.

-John


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## JRaef (Mar 23, 2009)

Big John said:


> With no failures in the circuit, current should be the same at any point on the wire. Voltage is consumed, current is not.
> 
> Something is causing your meter to read inaccurately. Try a different one.
> 
> -John


Big John is right, the voltage drop / resistance issues would affect current equally throughout the circuit. A common error is forgetting to turn off the Peak Hold button on your DMM, make sure you aren't reading that when at the motor OLR (I know because I do that all the time). :whistling2:


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## RIVETER (Sep 26, 2009)

Mikester1 said:


> I am working on a 480 volt motor that at the load side of the overload it is higher than at the MDP, which is about 50ft. away. Am I missing something here? I am thinking it would be just the opposite. Higher at the MDP and lower at the overload block with resistance of the wire and length of run, ambient temp...not the the other way around. I'm talking almost 10 amps of difference. What is this?:blink:


From where...to where are you taking your measurements? Are you taking the voltage measurement at the MDP with the motor ON...or...OFF?


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## Mikester1 (Jul 28, 2011)

I am sorry, I should have said the amperage in the original statement.


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## McClary’s Electrical (Feb 21, 2009)

RIVETER said:


> From where...to where are you taking your measurements? Are you taking the voltage measurement at the MDP with the motor ON...or...OFF?


 

Ummmmm, the title of the thread is AMPERAGE:whistling2:


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## Mikester1 (Jul 28, 2011)

Yes I know, but am I reading the replies wrong? Maybe I need to learn how to read my own posts. Geez. The way I'm reading the replies it sounds like people are refering to the voltage, not the amperage. If I'm wrong, sorry. I have used two Fluke RMS meters with the same results. Batteries brand new in both.


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## JRaef (Mar 23, 2009)

I don't think you're reading it wrong. We meant current. Regardless of what is going on with resistance in the circuit, current should be the same anywhere along the conductor. That's the law. So that leaves two possibilities: measurement error, which you seem confident isn't possible, or there is some other current consumer between the MDP and the OLR. Leakage to ground? Some unknown tap off? The next door neighbor connecting to the cables to power is pot farm grow lights? Something has to explain the difference if you are absolutely sure of the measurements, nothing in THAT CIRCUIT as described would explain current being different in two points.


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## JRaef (Mar 23, 2009)

JRaef said:


> I don't think you're reading it wrong. We meant current. Regardless of what is going on with resistance in the circuit, current should be the same anywhere along the conductor. That's the law. So that leaves two possibilities: measurement error, which you seem confident isn't possible, or there is some other current consumer between the MDP and the OLR. Leakage to ground? Some unknown tap off? The next door neighbor connecting to the cables to power is pot farm grow lights? Something has to explain the difference if you are absolutely sure of the measurements, nothing in THAT CIRCUIT as described would explain current being different in two points.


Oh wait, duh... You said the current reads higher downstream, so that phantom load theory doesn't work. Now I'm thinking measurement error again. Unless there is a VFD you didn't mention?


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## RIVETER (Sep 26, 2009)

mcclary's electrical said:


> Ummmmm, the title of the thread is AMPERAGE:whistling2:


You are right. I had a dumb ass attack.


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## nitro71 (Sep 17, 2009)

I'm curious what your real problem is? Is the motor tripping the overloads?


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