I was looking in a residential service panel today. 150A, 30 circuits, 15
per side.

For the circuits that run down the right side of the panel there is a bus
bar that holds the ground wires and a separate bus bar for the neutrals.
The ground wire to the water meter was attached to the neutral bar.

For the circuits that run down the left side of the panel there is a single
bus bar and the grounds and neutrals from each circuit are paired up under
each screw.

A strap connects the neutral bus bar on the right side to the
neutral/ground bus bar on the left side.

Why are there 2 separate bus bars on one side but a combination bus bar on
the other? Aren't they all electrically at the same point? If so, why
separate them on one side?

On 03/21/2014 12:12 AM, DerbyDad03 wrote:
I was looking in a residential service panel today. 150A, 30 circuits, 15
per side.

For the circuits that run down the right side of the panel there is a bus
bar that holds the ground wires and a separate bus bar for the neutrals.
The ground wire to the water meter was attached to the neutral bar.

For the circuits that run down the left side of the panel there is a single
bus bar and the grounds and neutrals from each circuit are paired up under
each screw.

A strap connects the neutral bus bar on the right side to the
neutral/ground bus bar on the left side.

Why are there 2 separate bus bars on one side but a combination bus bar on
the other? Aren't they all electrically at the same point? If so, why
separate them on one side?


Generally, in the first panel after the meter, the grounds and neutrals may land on the same bar.

For the second panel (sub-panel), the neutrals and grounds must be kept separate.

Jimbo wrote:
On 03/21/2014 12:12 AM, DerbyDad03 wrote:
I was looking in a residential service panel today. 150A, 30 circuits, 15
per side.

For the circuits that run down the right side of the panel there is a bus
bar that holds the ground wires and a separate bus bar for the neutrals.
The ground wire to the water meter was attached to the neutral bar.

For the circuits that run down the left side of the panel there is a single
bus bar and the grounds and neutrals from each circuit are paired up under
each screw.

A strap connects the neutral bus bar on the right side to the
neutral/ground bus bar on the left side.

Why are there 2 separate bus bars on one side but a combination bus bar on
the other? Aren't they all electrically at the same point? If so, why
separate them on one side?


Generally, in the first panel after the meter, the grounds and neutrals
may land on the same bar.

For the second panel (sub-panel), the neutrals and grounds must be kept separate.

Thanks for that information, but it only answers half of my question. This
part remains unanswered:

Why are there 2 separate bus bars on one side but a combination bus bar on
the other?

In other words, based on your answer, it's easy to wire the box as the
first panel because it doesn't really matter where you connect the grounds.
However, if the panel was used as a sub-panel then the grounds for any
circuit coming into left hand side would have to be run around the box to
the ground bar on the right hand side.

On Fri, 21 Mar 2014 04:12:51 +0000 (UTC), DerbyDad03
wrote:

I was looking in a residential service panel today. 150A, 30 circuits, 15
per side.

For the circuits that run down the right side of the panel there is a bus
bar that holds the ground wires and a separate bus bar for the neutrals.
The ground wire to the water meter was attached to the neutral bar.

There should also have been a green tinted screw or a dedicated strap
bonding the neutral bar to the can and grounding bar since this seems
to be the service panel.

For the circuits that run down the left side of the panel there is a single
bus bar and the grounds and neutrals from each circuit are paired up under
each screw.

This is a hazardous practice. A loose or faulty connection could cause
the ground to become hot through the neutral with current flow. Most
panels allow more than one grounding conductor per grounding bar
terminal.
Neutral bars sometimes are listed for more than one neutral.
I have never seen a panel approved to mix neutral and grounding
conductors in the same terminal.

A strap connects the neutral bus bar on the right side to the
neutral/ground bus bar on the left side.

This is commonly done to supply the needed number of neutral
connections and usually allow the circuits to be reasonably close to
each other.

Why are there 2 separate bus bars on one side but a combination bus bar on
the other? Aren't they all electrically at the same point? If so, why
separate them on one side?

Think grounding conductors to grounding bar, neutrals to neutral bar
but if a service panel the grounding conductors may be terminated to
the properly bonded neutral bar.
--
Mr.E

On 3/21/2014 12:12 AM, DerbyDad03 wrote:
I was looking in a residential service panel today. 150A, 30 circuits, 15
per side.

For the circuits that run down the right side of the panel there is a bus
bar that holds the ground wires and a separate bus bar for the neutrals.
The ground wire to the water meter was attached to the neutral bar.

For the circuits that run down the left side of the panel there is a single
bus bar and the grounds and neutrals from each circuit are paired up under
each screw.

I thought it was against code to put more than 1 wire under each
ground/neutral screw?

A strap connects the neutral bus bar on the right side to the
neutral/ground bus bar on the left side.

Why are there 2 separate bus bars on one side but a combination bus bar on
the other? Aren't they all electrically at the same point? If so, why
separate them on one side?

On 3/20/2014 10:12 PM, DerbyDad03 wrote:
I was looking in a residential service panel today. 150A, 30 circuits, 15
per side.

For the circuits that run down the right side of the panel there is a bus
bar that holds the ground wires and a separate bus bar for the neutrals.
The ground wire to the water meter was attached to the neutral bar.

For the circuits that run down the left side of the panel there is a single
bus bar and the grounds and neutrals from each circuit are paired up under
each screw.

A strap connects the neutral bus bar on the right side to the
neutral/ground bus bar on the left side.

Why are there 2 separate bus bars on one side but a combination bus bar on
the other? Aren't they all electrically at the same point? If so, why
separate them on one side?


In addition to what others have said...
My guess is that a ground bar was added to give more total spaces to
land ground and neutral wires.