250.121

[m sleem]

In light of 250.121, can to grounding point that located in electrical room other than main electrical room goes direct to earth?

 

[don_resqcapt19]

I have no idea of what you are asking.

 

[m sleem]

I meant the EGC of the electrical panels goes direct to earth.

 

[don_resqcapt19]

You cannot do that. The EGC must be run back to the location of the main or system bonding jumper, which ever may apply. 250.4(A)(5) prohibits the use of the earth as the effective ground-fault current path. 250.4(A)(3) requires all non-current conductive parts of electrical equipment to be connected to an effective ground-fault current path. If you are asking about connecting the code compliant EGC to earth at additional locations, there is no rule that prohibits that.

 

[m sleem]

You cannot do that. The EGC must be run back to the location of the main or system bonding jumper, which ever may apply. 250.4(A)(5) prohibits the use of the earth as the effective ground-fault current path. 250.4(A)(3) requires all non-current conductive parts of electrical equipment to be connected to an effective ground-fault current path. If you are asking about connecting the code compliant EGC to earth at additional locations, there is no rule that prohibits that.

Thanks

 

[m sleem]

... If you are asking about connecting the code compliant EGC to earth at additional locations, there is no rule that prohibits that.

Please correct me if i am wrong,

Grounding rods outside the building are intended for:

1- Eliminate sudden voltage due to lightning strikes.
2- Eliminate sudden voltage due to the starting current of motors.
3- Electrostatic discharge.

 

[GoldDigger]

Please correct me if i am wrong,

Grounding rods outside the building are intended for:

1- Eliminate sudden voltage due to lightning strikes.
2- Eliminate sudden voltage due to the starting current of motors.
3- Electrostatic discharge.

Grounding rods are not capable of eliminating anything. They:
1. May reduce sudden voltages due to lightning strikes. The high frequency components of the lightning related voltages, either induced or from direct strikes may be effectively reduced by a ground rod even though the DC resistance of the rod to soil is fairly high.
2. I do not see any way that a ground rod could significantly affect this voltage disturbance.
3. As long as there is an earth ground at the POCO secondary, any added ground on the customer end will have no noticeable effect on electrostatic discharge.

 

[m sleem]

2. I do not see any way that a ground rod could significantly affect this voltage disturbance.

If so, what is the use of SPD on motor panels?

3. As long as there is an earth ground at the POCO secondary, any added ground on the customer end will have no noticeable effect on electrostatic discharge.

What if POCO supply is medium voltage delta connection?

 

[m sleem]

If so, what is the use of SPD on motor panels?


What if POCO supply is medium voltage delta connection?

Also, release to earth the small leakage in network.

 

[m sleem]

If so, what is the use of SPD on motor panels?


What if POCO supply is medium voltage delta connection?

 

[Little Bill]

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