ronniet523
New User
- Location
- St. Louis
- Occupation
- Engineer
All, I'll start out by saying I'm a home DIY-er. I went to school for engineering and my dad was an electrician, but some of what you say may go over my head. That said, here is my problem...
When I use heavy loads for extended periods of time in my garage (miter saw, table saw, sanders, etc.), I have had other, unrelated circuit breakers in my house trip. My garage has a 50 amp subpanel that's powered by a 60 amp breaker from the main panel in the house. After doing some testing at the main panel I found that I have a voltage drop from neutral to ground that varies between 7V and 18V when my garage lights are on. That seemed pretty high to me so I did some testing at the garage outlets. My "North Wall" circuit outlets read 104V from hot to neutral when the lights are cold (just turned on), but then settle at 117V or so after they have been on for some time. The "West Wall" circuit outlets read 138V when the lights are cold, but then settle at 131V after some time. PLEASE ALSO KNOW THAT ALL THE LIGHTS ARE ON A SEPARATE 20A CIRCUIT. The numbers seem to make sense with the neutral to ground readings I took at the main panel, but I don't think they tell me things are working properly...
For some bonus testing, I experimented with adding heavier loads to both the North and West Wall circuits while the lights were on. I tried bringing down the 131V at the West Wall by running my table saw off there, and that took the West Wall outlets down to 116V between hot and neutral, and sent the North Wall outlets up to 131V! When I run the table saw on the North Wall, it shoots those outlets down to 104V from hot to neutral for a split second and then comes back to 116V. I forgot to check the West Wall in this case.
Sorry for the load of info. Just wanted to pass along the readings I have taken so far. I don't know what to try next... Can someone help?? Thank you for reading!!
-RT3
When I use heavy loads for extended periods of time in my garage (miter saw, table saw, sanders, etc.), I have had other, unrelated circuit breakers in my house trip. My garage has a 50 amp subpanel that's powered by a 60 amp breaker from the main panel in the house. After doing some testing at the main panel I found that I have a voltage drop from neutral to ground that varies between 7V and 18V when my garage lights are on. That seemed pretty high to me so I did some testing at the garage outlets. My "North Wall" circuit outlets read 104V from hot to neutral when the lights are cold (just turned on), but then settle at 117V or so after they have been on for some time. The "West Wall" circuit outlets read 138V when the lights are cold, but then settle at 131V after some time. PLEASE ALSO KNOW THAT ALL THE LIGHTS ARE ON A SEPARATE 20A CIRCUIT. The numbers seem to make sense with the neutral to ground readings I took at the main panel, but I don't think they tell me things are working properly...
For some bonus testing, I experimented with adding heavier loads to both the North and West Wall circuits while the lights were on. I tried bringing down the 131V at the West Wall by running my table saw off there, and that took the West Wall outlets down to 116V between hot and neutral, and sent the North Wall outlets up to 131V! When I run the table saw on the North Wall, it shoots those outlets down to 104V from hot to neutral for a split second and then comes back to 116V. I forgot to check the West Wall in this case.
Sorry for the load of info. Just wanted to pass along the readings I have taken so far. I don't know what to try next... Can someone help?? Thank you for reading!!
-RT3
