NEC 250.80

[erickench]

There was a change in the 2008 NEC which is now being used by New York. The above NEC section state's the following:

Metal enclosures and raceways for service conductors and equipment shall be connected to the grounded system conductor if the electrical system is grounded or to the grounded electrode conductor for electrical systems that are not grounded.

I am assuming that this applies to the case where meter enclosures are neutral bonded when they come from the factory. Is that the purpose of this rule?

 

[infinity]

There was a change in the 2008 NEC which is now being used by New York. The above NEC section state's the following:

Metal enclosures and raceways for service conductors and equipment shall be connected to the grounded system conductor if the electrical system is grounded or to the grounded electrode conductor for electrical systems that are not grounded.

I am assuming that this applies to the case where meter enclosures are neutral bonded when they come from the factory. Is that the purpose of this rule?

Sounds like you might be on the right track, also an ungrounded system is still required to have it's components grounded. How does this question apply to your situation?

 

[erickench]

I just came across this rule while reading one of Mike Holt's books. Is there any other rule that requires meter enclosures to be bonded to the grounded(neutral) conductor?

 

[erickench]

Okay, I now know the true purpose of this rule and why meter enclosures come with the neutral bond:

If lightning or a high-voltage line comes in contact with a metal service raceway/enclosure, the connecting path to the grounding electrode will limit the voltage.

 

[infinity]

Also think about a meter enclosure that has PVC or SE cable in and out of it. Without the neutral bonded to the metallic enclosure, the metal could become energized and nothing would clear the fault.

 

[don_resqcapt19]

2005 250.80 Service Raceways and Enclosures. Metal enclosures and raceways for service conductors and equipment shall grounded.

2011 250.80 Service Raceways and Enclosures. Metal enclosures and raceways for service conductors and equipment shall be connected to the grounded system conductor if the electrical system is grounded or to the grounding electrode conductor for electrical systems that are not grounded.

The change was not a real change. Wording was added to the 2011 code to make it clear exactly what the code wants us to do. There was no change in intent, just new words to tell us exactly how to "ground" the service equipment and raceways.

 

[erickench]

Also think about a meter enclosure that has PVC or SE cable in and out of it. Without the neutral bonded to the metallic enclosure, the metal could become energized and nothing would clear the fault.

If a bonded meter enclosure should come in contact with an ungrounded conductor there would be nothing to interrupt the circuit because it is upstream from the OCPD. The true purpose of the bond is to limit the voltage to earth. The new wording in the 2008 NEC demonstrates that there is a need for grounding the meter enclosure and service raceways to earth.

 

[erickench]

In a grounded system you would have the option of eliminating objectionable current by using PVC conduit or an unbonded(or insulated/isolated) connecting raceway between meter pan and service disconnect. However, you would still need the neutral bond in the meter pan in order to provide a current path to the disconnect where the grounding electrode is connected.