| Electronics > Repair |
| Question about voltage in U.S. house built in 1890 |
| << < (6/11) > >> |
| niemand:
I tested the last grounded receptacle in my dwelling unit, which is the one in the kitchen being used by the refrigerator and the stove. The two outlets on this receptacle (non-GFCI) measured correctly: 122 V from ground to hot, and 0.005 V from ground to neutral. |
| bdunham7:
--- Quote from: niemand on May 15, 2024, 03:47:48 am ---I tested the last grounded receptacle in my dwelling unit, which is the one in the kitchen being used by the refrigerator and the stove. The two outlets on this receptacle (non-GFCI) measured correctly: 122 V from ground to hot, and 0.005 V from ground to neutral. --- End quote --- Did you test that 4-plex outlet with the stuff plugged into the other sockets? If so, you probably just have a disconnect in the ground somewhere and leakage currents inside the various devices (like the UPS) are working like a voltage divider with the ground pins at the center. A low-impedance (Low-Z) meter would give you a different result and there probably isn't enough leakage current to zap you too hard. |
| niemand:
--- Quote from: Stray Electron on May 14, 2024, 03:54:48 pm ---...and the voltage that you're seeing from L1 to Ground is just from leakage. --- End quote --- What is "L1"? The hot contact on the outlet? |
| niemand:
--- Quote from: bdunham7 on May 15, 2024, 04:17:51 am --- --- Quote from: niemand on May 15, 2024, 03:47:48 am ---I tested the last grounded receptacle in my dwelling unit, which is the one in the kitchen being used by the refrigerator and the stove. The two outlets on this receptacle (non-GFCI) measured correctly: 122 V from ground to hot, and 0.005 V from ground to neutral. --- End quote --- Did you test that 4-plex outlet with the stuff plugged into the other sockets? If so, you probably just have a disconnect in the ground somewhere and leakage currents inside the various devices (like the UPS) are working like a voltage divider with the ground pins at the center. A low-impedance (Low-Z) meter would give you a different result and there probably isn't enough leakage current to zap you too hard. --- End quote --- Thanks. Not yet. It's got a very heavy desk right beside it, giving me only 4" of space. It's going to take some effort for me to gain adequate access. I don't know anything about a low-impedance meter. My DMM is just a cheap Kaiweets HT118A. I'm trying to understand your idea that leaky currents inside devices can work like a voltage divider.... What are "ground pins at the center"? What do you mean? |
| bdunham7:
--- Quote from: niemand on May 15, 2024, 04:27:47 am ---I'm trying to understand your idea that leaky currents inside devices can work like a voltage divider.... What are "ground pins at the center"? What do you mean? --- End quote --- Here's a schematic of a typical IEC AC inlet filter. Imagine you have 120VAC across L and N. What would you expect to measure across L and PE or N and PE? The capacitors form a voltage divider and if there is no other leakage and the PE is isolated (note that both PE terminals are connected to the case of the filter here) then the voltages across L/PE and N/PE would each be 1/2 of L/N. |
| Navigation |
| Message Index |
| Next page |
| Previous page |