I'm adding 2x20 Amp circuits to a main panel outside, but the main has 3 wire system. Also the main has 6 spaces for circuits, which allows me to add this circuits. The problem is the 3 wire system.

My question is, it's ok to run the circuits and bond the neutral and the ground in the main panel?

All the boxes are bonded, so I figure it out if the neutral gets severed then I have the ground to allow the current take that path. I'm not sure if it's ok to do it. Maybe I should bond the boxes to the iron from the foundation. Thanks in advance.

  • Where in the world are you? What do you mean by 3-wire service? Three phase, or biphase with two hots and a neutral? – longneck Nov 19 '18 at 19:01
  • I was thinking the same is this a 3 phase system since specifying 3 wire and 6 openings. More info is needed and the true type of power 3 phase or split phase will be needed to provide an answer. – Ed Beal Nov 19 '18 at 20:11
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    In what way is your three-wire system a problem? It's unclear why you think bonding is necessary at this juncture. – isherwood Nov 19 '18 at 20:54
  • I was referring to a old system of 2 hots and a ground – Cat Nov 20 '18 at 18:49

When adding a branch circuit, you would never, ever have cause to add any neutral-ground bond anywhere.

That should only be done as part of a total review and reassessment of your Grounding Electrode System (the network of bare/green wires from your ground bar out to your branches and appliances) and your Equipment Grounding Conductor system (the hefty copper wire heading out of your panel to a water pipe and/or driven-into-earth grounding rod or Ufer).

That's a pretty important set of systems for life safety, so if it looks like those systems are borked up in any way, seriously consider that review.

And then when it's done, land your branch circuit neutral wires on the neutral bar, and your ground wires on the ground bar. If this is definitely the main service panel, they might be the same bar.

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  • Thnx. I wasn't sure about it, I was expecting that if the house was built in 90's goes under the rules of that time. – Cat Nov 20 '18 at 18:40

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