The main bonding jumper provides a ground connection between the neutral ground bus and the service panel.
Electrical panel neutral and grounding.
Sub panels are grounded through the cable that provides the sub feed circuit power.
Main panels and sub panels.
Grounding a sub panel.
When grounding an electrical panel the following applies grounding a main panel.
For multiple panels the situation is more complex.
Please see nec article 250 28 for when to make a neutral to ground connection.
There are several different ways main panels are configured in homes here it is in a nutshell.
Neutral is a circuit conductor that normally completes the circuit back to the source.
That is for simple single panel installations.
This is a bare copper wire that connects the neutral ground bus bar to a ground rod driven into the earth near the service panel or to metal rebar in the home s.
Another ground connection is made by the grounding electrode conductor or gec.
A second panel or sub panel should have the neutral and ground terminals or bars isolated from each other this is why the main circuit feed to the sub panel must have 4 wires with a dedicated insulated wire for the neutral and a separate wire for the ground.
The tripped breaker shuts off the circuit s current preventing a potentially dangerous situation.
Neutral is usually connected to ground earth at the main electrical panel street drop or meter and also at the final step down transformer of the supply.
The ground bar is bonded internally when an external bond to earth is installed as described at the link for electrical grounding below.
By shunting excess line voltage back to the panel s neutral pole the ground current forces the circuit breaker to trip.
The electrical path main panel.
Installing a ground wire to your electrical service panel can be done easily with a few hand tools.
If your electrical panel is the first service disconnect point and the utility has only provided normally current carrying conductors phase and neutral wires plus a ground wire then no you do not make a neutral to ground connection.
Basically grounding is connecting to the earth.
The panel that s located directly after the electric meter is the main service panel.
Two live hot wires and one neutral.
This is a brief walk through of a simple grounding and bonding system and what happens with the flow of current in normal operation and in a ground fault c.