Am I Missing Something

[Mark S. Tyson]

Need some help electrical is probably my weakest link. On today's inspection i opened up the service panel (main) and noticed that the neutrals and grounds were sharing the same buse bar no problem except they were all double lugged when there are plenty of open terminals to allow for single lugs.
Then as i began testing individual devices discovered that probably 8 out 10 outlets had open grounds. So i randomly started to open the boxes and discovered that the ground wire were run into the boxes and not connected to the devices. What am i missing?

[mnahrgang]

The double lugging and the open grounds have nothing to do with each other... The open grounds are a defect, but easily corrected (attach the ground wire to the receptacle screw).

The double lugging (neutral & ground) sharing a common lug isn't great, but not that big of a deal.

Grounds can share lugs with other grounds, but neutrals cannot share lugs with other neutrals. When that happens it is a safety and fire issue. What you have is a relatively benign practice that technically isn't allowed but like I said isn't that big of a deal.

[Larry J. Michael]

See that all the time here.

[Brian E. Kelly]

The neutrals should not be sharing the same lug as the ground.

Although common practice in the past, it is a safety concern.

[Robert Meier]

Originally Posted by bkelly2

The neutrals should not be sharing the same lug as the ground.

Although common practice in the past, it is a safety concern.

I agree and this was specifically addressed in the 2002 NEC under section 408.21. Although the requirement had been part of the UL Panelboard Standard for quite a while prior to the 2002 they included the wording in the actual code language to emphasize the requirement. It was later moved to section 408.41.

408.41 Grounded Conductor Terminations.
Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor.
Exception: Grounded conductors of circuits with parallel conductors shall be permitted to terminate in a single terminal if the terminal is identified for connection of more than one conductor.

[mnahrgang]

Okay, granted having a ground and neutral under the same lug is not acceptable according to the NEC.

Beyond it not being "code compliant" shat is the potential harm in this? I've seen pictures of the harm of double lugging neutrals, but not a neutral and ground.

[Jae Williams]

Originally Posted by mnahrgang

Okay, granted having a ground and neutral under the same lug is not acceptable according to the NEC.

Beyond it not being "code compliant" shat is the potential harm in this? I've seen pictures of the harm of double lugging neutrals, but not a neutral and ground.

Double-lugging/tapping can create hot spots on breakers and neutral terminal bars because they are not tightened to the correct torque—especially if two different sized conductors are used. Because the hot (black) and neutral (white) wires are both current carrying conductors the chance is even greater for potential hot spots. If the double-tap/lug becomes loose, it may begin to arc. This will build up carbon increasing resistance, which will make it more difficult for the conductor to make contact—thus increasing the current (electrical draw). The end result may be the current exceeding the rating of the breaker; it becomes hot and trips. There may be signs of over-heating such as discolored wires and terminal screws, melted wires, etc., or worse yet—the possibility of fire exists.

[Michael Larson]

This will build up carbon increasing resistance, which will make it more difficult for the conductor to make contact—thus increasing the current (electrical draw

Something wrong here but I have to run for a bit.

Increased resistance would lead to less current but voltage would be distributed across 2 loads resulting in insufficient voltage at the appliance.

[Jae Williams]

Originally Posted by mlarson

Something wrong here but I have to run for a bit.

Increased resistance would lead to less current but voltage would be distributed across 2 loads resulting in insufficient voltage at the appliance.

When you return...

The electrical draw (amperage) is increased--more "push" is required to supply the demand. The "draw" may not appear at the appliance, but it is happening at point of the carbon build-up. That's why the breaker disconnects--increased heat generated by the increase in demand.

[Michael Larson]

Originally Posted by jwilliams4

When you return...

The electrical draw (amperage) is increased--more "push" is required to supply the demand. The "draw" may not appear at the appliance, but it is happening at point of the carbon build-up. That's why the breaker disconnects--increased heat generated by the increase in demand.

Depends Jae.

The push(voltage) is not variable in this case.

The poor connection causing arcing because instead of a near zero resistance you now have a few ohms and the current flowing through that resistance is creating heat. The current actually goes down in the circuit controlled by the breaker. I'm speaking of resistive loads here.

If there are inductive loads, like a motor, the current would go up as low voltage across the motor will produced increased currents.

So it depends if the load is resistive like lighting or a toaster or if it's inductive like a refrigerator.

[Jim Port]

Originally Posted by mnahrgang

Okay, granted having a ground and neutral under the same lug is not acceptable according to the NEC.

Beyond it not being "code compliant" shat is the potential harm in this? I've seen pictures of the harm of double lugging neutrals, but not a neutral and ground.

For one thing, if the conductors are not secured under the screw properly, you not only lose the neutral return path you also lose the safety ground should a fault occur. There could be no path back to the panel to clear the fault.

[mnahrgang]

Originally Posted by Jim Port

For one thing, if the conductors are not secured under the screw properly, you not only lose the neutral return path you also lose the safety ground should a fault occur. There could be no path back to the panel to clear the fault.

You have that same potential if they are under a screw all by themselves if the screw is loose. I would think that if the lug was rated for more than one connection, then it wouldn't matter.

[Bruce A. King]

The reason many inspectors assume the current went up with a loose breaker wire that caused the breaker to trip is this:

The bad connection creates heat that causes the breaker to react even when the current is much less than the rating on the breaker. This is due to the sensor mechanism in the breaker being a thermal device. Some newer breakers may be designed differently.

I had a neighbor that had a 200 amp breaker tripping due to a loose wire on it. The current flowing when it tripped was around 30-40 amps.

[agallatin]

In the case of arching wouldn't there be an increase in current or load , causing a tripped breaker ?

[Jae Williams]

Originally Posted by agallatin

In the case of arching wouldn't there be an increase in current or load , causing a tripped breaker ?

Most likey--see post #7.