Can ground and neutral be on same bus bar in a sub panel?

The answer is never. Grounds and neutrals should only be connected at the last point of disconnect. This would be at main panels only.

Can a sub panel have a separate ground?





An insulated neutral must also be separate from the ground bar at the subpanel and if installed in a separate building must have it’s own ground electrode with a solid #6 copper wire attached from electrode to the ground bar. The main service panel ground bar must be bonded and the subpanel unbonded.

Why are neutrals and grounds separated in a subpanel?

With ground and neutral bonded, current can travel on both ground and neutral back to the main panel. If the load becomes unbalanced and ground and neutral are bonded, the current will flow through anything bonded to the sub-panel (enclosure, ground wire, piping, etc.)

Can ground and common on same bus bar?

If the main service panel happens to be the same place that the grounded (neutral) conductor is bonded to the grounding electrode, then there is no problem mixing grounds and neutrals on the same bus bar (as long as there is an appropriate number of conductors terminated under each lug).

Does a sub panel in same building need a ground rod?

Yes, any sub panel outside of the main building requires it’s own ground rod and a ground wire back to the main building. And yes, a sub panel in the same building as the main does not need a ground rod – only the ground wire.

Why are neutral and ground tied together in main panel?





Bonding the neutral and ground wire in the main panel is important for the circuit breaker to function properly. A problem could continue without triggering a circuit breaker to cease the electricity if there isn’t a quick and drastic rise in electrical current.

Does sub panel need to be bonded?

Rule #3: In a subpanel, the terminal bar for the equipment ground (commonly known as a ground bus) should be bonded (electrically connected) to the enclosure. The reason for this rule is to provide a path to the service panel and the transformer in case of a ground fault to the subpanel enclosure.

Does a subpanel in a detached garage need a ground rod?

The detached structure is required to have its own Grounding Electrode System (GES) i.e. ground rods. The subpanel in the detached structure will have its grounds and neutrals separated.

Is one ground rod enough?

This “earth ground” is a very important part of your electrical system to ensure electrical safety. According to the National Electrical Code, or NEC, a ground system should have a grounding resistance of 25 ohms or less. 2 Achieving this may require more than one ground rod.

Can rebar be used as a ground rod?



Proper Grounding Rod
Use the proper type of grounding rod. In most cases, pipe or rebar can be used. The grounding rod needs to be made of galvanized steel and also needs to be at least four feet in length for best results.

Why are there two grounding rods?

If it has a ground resistance of 25 ohms or more, 250.56 of the 2005 NEC requires you to drive a second rod. But many contractors don’t bother measuring the ground resistance. They simply plan on driving two rods because doing so will meet the requirements of 250.56, regardless of actual ground resistance.

What size ground rod is needed for a 400 amp service?

The ground wire should be 1/0 copper with a rod 4 to 6 below grade. It’s possible that the conductors for 400 Amp services are 400 cir.

What size ground do I need for a 1200 amp service?



Ground Wire Size Table

Rating or Setting of Automatic Overcurrent Device in Circuit Ahead of Equipment, Conduit, etc. Not Exceeding (Amperes) Copper (AWG or kcmil) Aluminum (AWG or kcmil)
1000 2/0 4/0
1200 3/0 250
1600 4/0 350
2000 250 400

How many ground rods do I need for 600 amp service?

MIN. SIZE OF EQUIPMENT GROUNDING CONDUCTORS (EGC) for Grounding Raceway & Equipment

Rating or setting of Automatic Overcurrent Device (OCPD) in Circuit ahead of Equipment [i.e Circuit Breaker]. Not exceeding (Amps) Size (AWG or kcmil)
500 2 1/0
600 1 2/0
800 1/0 3/0
1000 2/0 4/0