Did an inspection today on a home built in 2005. The service panel is outside and the distribution panel is located in the garage directly behind the service panel. There are only 3 conductors running from the service panel to the distribution panel and the conduit connecting them is plastic.
The panel has 2 neutral bars located on each side of the main busses which hold the circuit breakers. There is a metal bar at the top that connects the 2 busses. The panel does not have a separate ground buss.
The neutral wires are connected to the buss on the left and the ground wires are connected to the buss on the right. The right buss has a bonding screw installed which in this case is bonding the neutrals and the grounds to the panel.
I pointed out that the neutrals and grounds are only permitted to be connected together in the service panel and that there should be 4 conductors between the panels so that the grounds and neutrals can be isolated from each other. The buyer asked me how the home could have passed an electrical inspection and I told him that it should not have. That was where it got sticky.
The seller was also present and asked what the problem was. I explained it to him and he was not too happy. It turns out that he is a building inspector for the county where the home is located. He got on the radio and called the chief electrical inspector, who is supposed to go there tomorrow.
I know it is not supposed to be done that way but my question is, what danger is there from having the neutrals and grounds connected together and bonded to the panel?
The first photo shows the entire panel and the second shows the bar connecting the two busses and the bond screw.
As you’ve stated there needs to be 4 conductors between the disconnect and the panel. Also there is no GEC(s) terminated at the service disconnect adjacent to the meter, another issue that needs to be rectified.
The conduit was plastic and could be seen in both panels. I know it is not right, although I didn’t think about the shelves reducing clearance.
What I am trying to figure out is what danger does this cause. The wiring is not correct and the grounds are connected to the neutrals 8 inches (the thickness of the block wall) away from the service panel. Both panels are still grounded through the neutral since they are connected together. I realize that if the neutral were to be disconnected there would be a problem but is that the only real danger with the panels wired this way?
Not necessarily. By segregating the neutrals and the EGC’s, we establish only one low impedance path back to the source for neutral currents. When neutrals and EGC’s are bonded at various other points in the system, we create multiple paths for return currents. We must forget the incorrect common beliefs “current takes the shortest path back”, or, “currents take the least resistive path back to the source”. Current does neither, it takes every path back to the source.
Kirchhoff’s Law teaches us that current will divide through every path based on the resistance each individual path affords. Now, when multiple paths exist, current then begins flowing throughout an entire electrical distribution system and every bonded component thereof. These currents are sometimes referred to as transient currents or objectionable currents. Granted, this current flow is usually only a slight percentage of the total circuit current, but it can cause many issues. They can create a fire or shock hazard, but more commonly create electromagnetic interference in electronic equipment.
Robert, you found out why it is not a great idea to discuss a problem with the buyer AND THE SELLER at the same time in person!
You put yourself in between them onsite, instead of on paper.
I avoid these situations at all costs, as they quickly put you way behind schedule, and I really do not care to get into debates with Sellers. I let them do that on their own time with whoever they want.
