Thread: Grounds and Neutrals Under Same Lug

On a recent inspection of a 1991 home, grounds and neutrals were found under the same lug in the service panel. My understanding is that neutrals and grounds can't be under the same lug. Only one neutral per lug and up to three grounds per lug providing they are the same size. Can anyone advise what year the code changed for seperating grounds and neutrals? Thanks in advance!

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Originally Posted by Brian Harwood

On a recent inspection of a 1991 home, grounds and neutrals were found under the same lug in the service panel. My understanding is that neutrals and grounds can't be under the same lug. Only one neutral per lug

Correct - only one neutral per terminal.

... and up to three grounds per lug providing they are the same size.

Mostly incorrect, but could be correct.

For the gounding conductors you need to read the lable. Older panels limited the gounding conductors to 1 per terminal, newer panels 20-30 years old and newer maybe?, allowed 2 per terminal, and some newer panels allow 3 per terminal. The only way to know is to take a few minutes and read the label, after reading a few labels you should be able to quickly find where those ratings are.

Can anyone advise what year the code changed for seperating grounds and neutrals?

Never was allowed ... sort of was allowed but not allowed ... I'll explain: The NEC now strictly prohibits more than one neutral in a terminal, previously, the terminals were, and still, only allowed to have one conductor per terminal unless identified for more than one, then the terminal will state how many of what size.

The catch is that no terminal was ever listed for use for two neutral conductors, so, while the NEC was silent on the issue (meaning it was allowed if so listed), nothing was listed for that use (meaning it was never allowed).

Kind of like the dog chasing its tail, once it gets its tail, nothing is different, it's still a dog, it still has a tail, and it is still going in circles.

Jerry answered your question, but I thought I'd try to explain why it is dangerous. It also helps me to get it right in my mind.

The simple explanation: when needing to work on a circuit and you attempt to disconnect the neutral, you would still want the grounding conductor solidly connected to the ground rod - for safety.

Another explanation: AC current is traveling back and forth between the hot and neutral (ungrounded and grounded). If you have the neutral under the same screw with the ground and something isn't tightened well, then the electricity will take the path of least resistance and could energize the ground wire.

I was doing a seller's (pre-listing) inspection the other day and the seller told me the ground wire for the master bathroom light kept shocking him. I said, "stop touching it"

Jerry and Bruce I really appreciate your replies.

Originally Posted by JB Thompson

Jerry answered your question, but I thought I'd try to explain why it is dangerous. It also helps me to get it right in my mind.

The simple explanation: when needing to work on a circuit and you attempt to disconnect the neutral, you would still want the grounding conductor solidly connected to the ground rod - for safety.

The connection to a ground rod has nothing to do with the normal operation of the circuit. The electrode is for high voltage events like surges and lightning strikes.

Another explanation: AC current is traveling back and forth between the hot and neutral (ungrounded and grounded). If you have the neutral under the same screw with the ground and something isn't tightened well, then the electricity will take the path of least resistance and could energize the ground wire.

If the bus screw was loose there is a good chance the circuit would not even be working. How would the grounding conductor become energized? It is there in the event of a fault. The loose screw would be an open circuit or a high resistance circuit.

Electricity takes all paths, not just least resistance.

Originally Posted by Jim Port

Electricity takes all paths, not just least resistance.

That is correct. That is why you can get a shock from an energized circuit, but not a painful burn. Most of the electrical flow will take the wire, which has less resistance. A tiny portion will flow thru your body, or thru your skin to the floor. The higher resistance prevents a fatal shock.

Now take the neutral connection away at the panel. All the electrical current will now take the high resistance path thru your body and you are shocked to sh&t!

Anything that compromises that neutral connection is a hazard, and that is a good reason to have each under its own tight screw.

Originally Posted by Robert Meier

You have it backwards, a shock from an open neutral puts you in series with the load which has a resistance therefore limiting your shock potential (the three resistances, the conductor, the load and your body are additive). If you contact the phase conductor and a solidly grounded object your only limit besides your body is the very low resistance of the conductor itself.

So in one case you have your body and the resistive limits of the load and the conductor, in the other case you have your body and almost no other resistance except for that of the conductor.

Open neutral, your body could be in series, offering the only path.
Touch a live wire, your body is a parallel resistor, but the low resistance wire carries the bulk of the current.
I guess you are saying that the parallel is worse than series so, sure, I will accept that. I don't know.

Originally Posted by Jim Port

How would the grounding conductor become energized? It is there in the event of a fault. The loose screw would be an open circuit or a high resistance circuit.

Electricity takes all paths, not just least resistance.

via the grounded conductor. Say perhaps one bus lost (half/split phase conductor) or single pole opened (one hot open) of the two on a MWBC (shared netural) such as commonly found on older homes supplying the lighting and appliance branch circuits - where the other bus or hot conductor remains energized/closed and is under load (working electricity)= backfeed on the neutral (grounded conductor) of the MWBC and therefore objectional current possible on the grounding conductor.

Safety issue generally as SE panels are worked energized. Opening (removing) neutral from terminal not possible without disturbing continuity/bonding of and/or making contact with grounding conductor. N/G bond of Service equiment always to be made before energzing and before connection to utility conductors/drops/laterals . Repairs/corrections to N & G bond utility physical disconnect first.

So you think a loose connection at a bus bar is going to cause the electric to flow back to the receptacles and jump over to the grounding conductors?

Originally Posted by Jim Port

So you think a loose connection at a bus bar is going to cause the electric to flow back to the receptacles and jump over to the grounding conductors?

You quoted Bruce (JB Thompson) and pontificated with your deluded false 'rhetorical' question.

I quoted same and responded thereto.

You are the one who introduced "loose screws". The Topic being discussed was neutral conductors sharing the same terminal on the grounding/grounded bus. You asked HOW the grounding conductor of a circuit could be energized. I gave an example - open half phase conductor with the other half phse conductor still energized and under load - thus current upon the neutral conductor of the MWBC and thereby objectional current to the circuit grounding conductor sharing the same terminal.

Perhaps when you've been absent a discusssion you might bother reviewing just what is being responded to and look back to YOUR OWN posts quoting prior.

Where is the crossover that is putting this current on the grounding conductor? There is one connection at the bus. There is none at the devices. We are not talking about a bootleg neutral ground connection.

Since the electrons are trying to get back to the source, why are you saying they would be going away from the panel?


BTW HG, is your ego so fragile you feel the need to demean someone just so you can have a sense of worth?