Different Screw on Neutral and Ground Bar

[wdconnors]

I'm in the process of adding a 2nd AC and a new 20 amp breaker and I started working in the breaker box last night and saw something that gave me pause. The middle screw on the neutral and ground bars is different than the others. The threads of both of those screws are also painted green.

I can't find anything from the manufacturer that says those slots aren't normal connection points, but I have no idea why the screw is different. There's even a spot where two ground wires are under the same single screw instead of using the other spot, which again, gives me pause.

Any thoughts?

[sanjaun2]

I can't really tell in the picture, Does the middle screw help secure the bar? Either way it is ok to put two wires under each screw. Just make sure they are secured well.

[wdconnors]

That's what I thought initially, but no it does not. Putting two wires under a single screw is not code and I'd prefer not to unless I had no other options.

[gnach]

Ground wires can, neutrals (white) not. You can find a small neutral add-on block to add your 2nd AC. Typically it attaches with self-tapping screws to the existing. Lowe's, the Depot or a decent hardware store should have it.

[TurnerFam]

what 'code' are you referring to?? This is an RV, not a home - different animals.

[Beau388]

Originally Posted by TurnerFam

what 'code' are you referring to?? This is an RV, not a home - different animals.

The RVIA has adopted the 120 volt NEC code for all RVs carrying that seal. The RVIA has its own code for 12 volt wiring. <https://www.rvia.org/standards-regulations/standards-compliance/association-and-ansi-standards>

[The Gritz Carlton]

Any reason you wouldn't use a 30A breaker instead of a 20? Is this a dedicated circuit for the A/C?

[Beau388]

Originally Posted by The Gritz Carlton

Any reason you wouldn't use a 30A breaker instead of a 20? Is this a dedicated circuit for the A/C?

Circuit breakers are there to protect the wiring and not the device using the electricity. If your wiring is 10 ga to the A/C, then it is ok. If the A/C wiring is 12 ga then stick with a 20 amp. There is a new (well relatively new) type of circuit breaker - arc fault circuit interrupter (AFCI). While considerably more expensive than a traditional circuit breaker, I think it is well worth the price. If you find a AFCI tripping, then there is probably a loose wire clamp or wire nut in the circuit.

[wdconnors]

Called the manufacturer. They said the bars used to be held on by the middle screws which probably explains the goo on the threads (prevent it from coming loose). The newer ones have bars attached using a screw on the far left and far right. I know my neutral bar is connected like that but not sure about ground.

Basically if I take the middle screws out and the bars are still attached I can use it as a connection point.

[The Gritz Carlton]

"Circuit breakers are there to protect the wiring and not the device using the electricity. If your wiring is 10 ga to the A/C, then it is ok. If the A/C wiring is 12 ga then stick with a 20 amp."

It's the draw from your appliance that will trip the breaker...not the gauge of the wire.

[16ACE27]

Originally Posted by The Gritz Carlton

"Circuit breakers are there to protect the wiring and not the device using the electricity. If your wiring is 10 ga to the A/C, then it is ok. If the A/C wiring is 12 ga then stick with a 20 amp."

It's the draw from your appliance that will trip the breaker...not the gauge of the wire.

This is true. In most cases the wire size is based on load size, which also determines the breakers size. If the load pulls too much current the wire will over heat and destroy itself (and maybe more). The circuit breaker interrupts that current and saves the wire and maybe the RV or house.

[Beau388]

Originally Posted by The Gritz Carlton

"Circuit breakers are there to protect the wiring and not the device using the electricity. If your wiring is 10 ga to the A/C, then it is ok. If the A/C wiring is 12 ga then stick with a 20 amp."

It's the draw from your appliance that will trip the breaker...not the gauge of the wire.

True, but if you use a 30 amp CB with 12 gauge and your device draws 28 amps, the wire will over heat (exceed 90 degrees C) and possibly start a fire. The National Electric Code (NEC) states the BC or fuse is there to protect the wire and not the devices on the feed.

[wdconnors]

Originally Posted by TurnerFam

what 'code' are you referring to?? This is an RV, not a home - different animals.

Electrical code - it runs 120V just like a house and will burn down just like a house.

Originally Posted by The Gritz Carlton

Any reason you wouldn't use a 30A breaker instead of a 20? Is this a dedicated circuit for the A/C?

20 amp max breaker per the manufacturer and I'm running 12 gauge wire.

Breakers and wire size are determined by length of run, device, etc. - you can't just wing it.

[Crossleyt]

That green screw on the neutral bus means the neutral bus is bonded to the metal enclosure. The green screw on the ground bus means the same thing. In a main panel such as in a motorhome, the neutral and ground buses are bonded together, electrical the same. Hope this helps.

[16ACE27]

Originally Posted by Crossleyt

That green screw on the neutral bus means the neutral bus is bonded to the metal enclosure. The green screw on the ground bus means the same thing. In a main panel such as in a motorhome, the neutral and ground buses are bonded together, electrical the same. Hope this helps.

No, no, no. The ground and neutral in an RV are NEVER bonded together until:
A: You plug into shore power - in which case they are bonded at the source main panel.
B: You engage the onboard generator.


And nobody here was talking about green screws which are normally on the panel itself and used to ground the panel to the ground buss.

[ComputerChips]

To the original question. It's pretty obvious. If the odd screw goes all the way through the hole and into something underneath, it is a mounting screw. If its a short set screw like the others you can put a wire in the hole and tighten it down.