I have 240 electric going to a machine. Motor keeps tripping, not service panel breaker but at the overload at the motor. I'm checking shorts, ground etc. I have 240 going to this motor. Its the right motor. I wanted to know if these readings were good as I tested the 3 legs at the disconnect at my machine. Between each pair of wires I get 237 V. I did another test. Ground to each of these also y white wire I got 158 Black wire I get 134 Red wire is 122 Is this OK? Also, how can you tell which legs are L1, L2, and L3? Which wire is neutral?
Heya! Your measurements from each wire to ground (white: 158 V, black: 134 V, red: 122 V) seems a bit unusual for a standard residential 240 V setup. Typically, in a 240 V three-phase system, you would expect about 120 V from each phase to neutral or potentially up to 139 V in a high leg delta where one leg (often marked orange) is higher voltage to neutral. However, the readings you provided do not conform to these typical values, which could suggest an issue with the neutral connection or an imbalance. For identifying L1, L2, L3, and Neutral the standard color coding for AC power wiring in a three-phase system is typically black, red, and blue or black, red, and white for the phases, with white or gray for neutral. This can vary, so it’s important to use a multimeter or a voltage tester to confirm. You can check the voltage between pairs: L1 to L2, L2 to L3, and L1 to L3 should all give you similar readings (like your 237 V readings) if everything is connected correctly and there's no high leg. To find neutral, normally one would look for the conductor that has a consistent lower voltage relative to all phases (around 120 V in many setups). Possible Issues... The unusual voltages to ground could be due to a poor neutral connection or other wiring issues. This could also contribute to the motor tripping if it's causing an imbalance or insufficient grounding. It’s important to ensure that the motor is configured correctly for the type of electrical service you have. Check the motor's wiring diagram and settings to make sure they match the supply. Verify the neutral connection and ensure that it is properly grounded. Check the entire system's wiring to ensure that all connections are secure and correctly configured. Always ensure that all power is turned off and follow safety protocols when modifying electrical systems. Verify the wiring in the panel for the outlet as well.
Thank you! I appreciate your help. This is a factory. Old big punch presses. 1930, 40's, 50's and 60's. Built to last. I work on these. I'm their tech. Just been hurting on this machine. Brand new motor, 3 phase, wired correctly verified act like it wants to move for a second then the heated blow. These heaters you can't find rest either. General electric ones that are from the 60s or 70s. The wiring in this place is all kinds of bad. Family owned small company since 1902. Really bad electrical stuff. Wrong color wires, osha would have a field day. This is why I am asking how to tell leg 1 vs leg 2 vs leg 3. This machine is plugged into a receptacle and then to a normal size service panel. I took the readings I got from my volt meter and walked a good way across the building to a machine I know runs good. I tested the legs and got the same everything. Oh well. I don't know.
Sounds like a wiring issue... probably either at the outlet itself or in the breaker box. Maybe want to shut off the breaker to the outlet, check that power is indeed off at the outlet, and then unscrew the outlet and check to make sure it's wired properly and that no wires had possibly popped loose. You can take a look at this video, th-cam.com/video/1PANFpoUy2w/w-d-xo.htmlsi=KQW3PJaxYrEPMky1&t=631, at the 10 min 31 sec mark to see when I wired up the outlet to see how it should be wired. If everything looks good you would need to check at the breaker itself... Be sure to follow all safety guidelines and if not comfortable have a professional take a look.
Thanks for the response! I also checked across the breaker and got 220 or so at the breaker. Possibly the breaker? Do you see that these outlets go bad often?
Your hot to neutral reads 220v?? It should be 110/120 from hot1 to neutral/ground and 110/120 from hot2 to neutral/ground, and only 220/240 from hot1 to hot2.
Really good explanation. Thanks!
@vcpvcp2889 no problem, thank you!
I have 240 electric going to a machine. Motor keeps tripping, not service panel breaker but at the overload at the motor. I'm checking shorts, ground etc.
I have 240 going to this motor. Its the right motor.
I wanted to know if these readings were good as I tested the 3 legs at the disconnect at my machine.
Between each pair of wires I get 237 V.
I did another test.
Ground to each of these also y
white wire I got 158
Black wire I get 134
Red wire is 122
Is this OK?
Also, how can you tell which legs are L1, L2, and L3? Which wire is neutral?
Heya! Your measurements from each wire to ground (white: 158 V, black: 134 V, red: 122 V) seems a bit unusual for a standard residential 240 V setup. Typically, in a 240 V three-phase system, you would expect about 120 V from each phase to neutral or potentially up to 139 V in a high leg delta where one leg (often marked orange) is higher voltage to neutral. However, the readings you provided do not conform to these typical values, which could suggest an issue with the neutral connection or an imbalance.
For identifying L1, L2, L3, and Neutral the standard color coding for AC power wiring in a three-phase system is typically black, red, and blue or black, red, and white for the phases, with white or gray for neutral. This can vary, so it’s important to use a multimeter or a voltage tester to confirm.
You can check the voltage between pairs: L1 to L2, L2 to L3, and L1 to L3 should all give you similar readings (like your 237 V readings) if everything is connected correctly and there's no high leg. To find neutral, normally one would look for the conductor that has a consistent lower voltage relative to all phases (around 120 V in many setups).
Possible Issues... The unusual voltages to ground could be due to a poor neutral connection or other wiring issues. This could also contribute to the motor tripping if it's causing an imbalance or insufficient grounding. It’s important to ensure that the motor is configured correctly for the type of electrical service you have. Check the motor's wiring diagram and settings to make sure they match the supply.
Verify the neutral connection and ensure that it is properly grounded. Check the entire system's wiring to ensure that all connections are secure and correctly configured. Always ensure that all power is turned off and follow safety protocols when modifying electrical systems.
Verify the wiring in the panel for the outlet as well.
Thank you! I appreciate your help.
This is a factory. Old big punch presses. 1930, 40's, 50's and 60's. Built to last.
I work on these. I'm their tech. Just been hurting on this machine. Brand new motor, 3 phase, wired correctly verified act like it wants to move for a second then the heated blow. These heaters you can't find rest either. General electric ones that are from the 60s or 70s.
The wiring in this place is all kinds of bad. Family owned small company since 1902. Really bad electrical stuff. Wrong color wires, osha would have a field day. This is why I am asking how to tell leg 1 vs leg 2 vs leg 3. This machine is plugged into a receptacle and then to a normal size service panel. I took the readings I got from my volt meter and walked a good way across the building to a machine I know runs good. I tested the legs and got the same everything. Oh well. I don't know.
I’m getting 120 from neutral to hot. Nothing from the other neutral-hot and nothing across the two hots. What do you think?
Sounds like a wiring issue... probably either at the outlet itself or in the breaker box. Maybe want to shut off the breaker to the outlet, check that power is indeed off at the outlet, and then unscrew the outlet and check to make sure it's wired properly and that no wires had possibly popped loose. You can take a look at this video, th-cam.com/video/1PANFpoUy2w/w-d-xo.htmlsi=KQW3PJaxYrEPMky1&t=631, at the 10 min 31 sec mark to see when I wired up the outlet to see how it should be wired. If everything looks good you would need to check at the breaker itself... Be sure to follow all safety guidelines and if not comfortable have a professional take a look.
Thanks for the response! I also checked across the breaker and got 220 or so at the breaker. Possibly the breaker? Do you see that these outlets go bad often?
I don't understand. Why is hot to neutral 220v, while hot/neutral to ground is 120v??
Your hot to neutral reads 220v?? It should be 110/120 from hot1 to neutral/ground and 110/120 from hot2 to neutral/ground, and only 220/240 from hot1 to hot2.
@@D3RPZILLA oh I see
If that's a properly wired 240v outlet, the top slot would actually be ground, not neutral.
Agreed - but does that fact affect the test method or results in the video?
Test results are the same.
Yes, thank you!