Electricity: If a sub panel was wired just like the main panel (ground and neutral bonded) what is the danger?
-- The inspector approved it in 1990, but now I read that the new codes require that the sub panel must isolate the ground and neutral wires in the sub panel.
What is the danger of my situation?
Added question: If I unscrew the green screw bonding the one bar in the sub panel, what will ground the the sub panel case? I hope I do not have to pull everything out and float the neutral bar and add a ground bar to the sub panel .
(I really don't want to call the new inspector and pay the $85 dollar inspection fee. If I call him and ask him for advice, he will insist on looking at again and charging me for the visit. (I know this because I have several rentals and I have called him before and he always says "I cannot give advice over the phone. I guess he is right about that.
But I am open to suggestions. I was licensed in Texas but now live in Arkansas)
Dang --- In my case it would happen right at the bus bar in the sub panel.
because about 20 years ago I thought about that and sent two insulated wires from the sub panel to the main panel.
(not realizing that both insulated wires are stripped bare to connect to the sub panel's (one) bus bar. But I was thinking the sub panel was right next to the main panel and the main panel has the neutral and ground wires both on the same bus. I was figuring that the way I wired the sub panel -- the sub panel would "think" it was inside the main panel.
In the main panel the code allows the ground wire and neutral wire to both connect to the same bus bar. Why? That short distance plus the bus bar has the big neutral wire (cable) connected to it going back to the electric company sub station. -- The push pull effect of the electron flow. Well sort of the "push pull effect" --- I know it is all push but you know
Main Panel, of course, it is grounded to the grounding rod (via the meter case)
But it is strange the code allows the ground wires and neutral wires to share the same bus bar in the main panel. I wonder why. It seems it would be better if the main panel also had two bus bars; one floating neutral bus and one bonded ground bus (which would be connected to the grounding rods.
BTW: The new codes require two grounding rods for a sub panel in a detached building. (or a 1/4 inch metal plate buried 20 inches deep.) btw: I think that is a good policy for defense against some lightening strikes. Of course we all know, there is no defense against a direct hit against a huge mega strikes.
Now, they have a fancy way of floating the neutral bar in the sub panels. Plastic insulation and all.
BTW: The new codes want the grounding rods driven 8 feet in the ground.
Here in Arkansas that is just about impossible without a back hoe.
Well Arkansas protested and the NEC added that a 2 square foot 1/4 inch plate could buried in the ground to replace the grounding rod requirement.
The inspector at the time said that the sub panel was wired just as if it was a circuit breaker inside the main panel. So what ever is said about a main panel bonding the neutrals and grounds to one bus would apply to the arrangement of the above described sub panel.
I will still take your advice and attach a ground bus to my sub panel and rewire it to current codes.
Specifically, in the sub panel I will float the neutral bus, bond the ground bus -- all white wires to the neutral bus, all bare wires to the ground bus,
Ironically, once I back feed with a main circuit breaker in the sub panel, both the neutrals and the grounds in the sub panel will eventually have a path to the one bus bar in the main panel.