I have a small subpanel next to my main house panel with only 4 slots. I am out of breaker spaces, so I've routed 8 gauge wiring (2-120V split phase, 1-nuetral and 1 ground) to the new sub-panel. Very short run of less than 6 feet of wiring between the panels.
I have filled only two slots with a ganged 30 amp breaker in the sub-panel that I need for some testing equipment in my garage (both panels and in a detached garage). I will likely put 2 additional 15 amp breakers in the future in the sub-panel. I have tied all 8 awg wires into the main busses.
Neutral and ground are bonded, but I've run separate wires to the bonded bus. I believe this is a very conservative, safe installation, but is it code, or even good practice? The 8 gauge wiring is ultimately protected by the main disconnect breaker (200 amps) since I've tied to the buss directly, but the voltage drop in only 1-2 volts, so even a direct short should not overheat the wiring.
I don't have any spare slots in the main panel to install a ganged 50 amp breaker – would like to do that, but just don't have the space. I guess I could pull two existing 15 amp breakers, install the ganged 50 amp and reroute the existing services to the new 15 amp breakers in the sub-panel – and I can do that if the only safe installation.
Should I re-wire or not?
Best Answer
So, you have 8 gauge wire potentially subject to a fault current of up to 200 amps without anything tripping. You also have the neutral and ground bonded in a sub-panel (despite running separate neutral and ground wires to it, so bonding in the sub-panel is a puzzling choice in itself, as well as being a violation.) [or else possibly you have written unclearly about what you have done with the ground and neutral?]
Wrong. Just....wrong.
Pull two breakers, insert a 50 A breaker, and move the 15A circuits to the sub. And unbond/isolate the neutral and ground in the sub. Get a different/larger sub-panel if you need additional circuits (or give a long hard look at a complete panel replacement with adequate spaces in the main panel - not all that expensive if the incoming service is adequate, but attached to a panel with few spaces.)
If your panel is listed for them breakers with two separate 15A circuits in a single space breaker are another option to make space.