Using a 'dummy' generator to test disconnections between a main panel and a sub-panel

If you want to test that your main panel and sub-panel are properly connected, you can unplug the sub-panel. Then, using wires or a 240V appliance cord, connect the _unpowered_ sub panel to the main panel *through another electrical sub-panel you know works*. Do NOT plug in the sub-panel to the wall; simply 'siphon' power from a known-working circuit.<br><br>Next, plug in a simple electrical appliance (like a nightlight) to the sub-panel. Then: you should not see any lights in the sub-panel if it is properly unconnected to the wall.<br><br>If you do see a light, there is an issue disconnection between the two panels. If _no_ lights appear, then there is no connection between the two panels. Ensure 100% that there are no 'siphoned' connections to any 'common' earth ground (like a metal grounding clip in either the 240v panels) because if you do they will usually 'light' the panels, regardless of the main power connection.<br><br>This is a simple 10 min check that tells you whether you properly _disconnected_ your electrical circuit. Ensure you _always unplug_ *before* trying this check! <br><br>-That being said, if you have no idea what I'm talking about, _never, never, never_ do electrical work without adequate training!! <br><br>**TL;DR** Using another ~240V panel to 'test' disconnects, and a nightlight (or 20W appliance) to check performance.