Reading a meter
A meter reads the voltage between two points, so its two leads always touch two different points. A clamp meter reads the current in the wire inside its jaws. You move the leads and the clamp and see what each reading tells you.
Open the visualFree, no sign-up. Works on a phone, tablet, computer, or projector.
What to try
- 1Start on Hot to neutral with the heater on. The meter reads a little under 120 volts, because the wires lose some voltage on the way.
- 2Set Meter leads to Both on hot. The meter reads zero, but the hot is still live.
- 3Set Clamp around to Whole cable. The current going out cancels the current coming back, so the clamp reads zero.
NEC 2026 sections it covers
- 250.24(B)
- Past the service, the neutral and ground stay apart.
- 408.40
- A panel's ground bar is bonded to its metal case.
Section numbers only. Read the full text in your code book. Temperatures and times in the visual are teaching models.
See something wrong? Tell us and we will check it against the code.
More visuals
- A circuit is a loopCurrent flows only when it has a full path out and back. Open the switch or break a wire and watch it stop.
- Conductors and insulatorsPut copper, aluminum, rubber, or skin on the meter and see how hard each one makes it for current to get through.
- Volts, amps, and ohmsChange the voltage or the heater and watch the amps follow. Amps equal volts divided by ohms.