need clarifiction

[hotblueelectric]

Just checking if I am correct. This is confusing me. If I undeerstand this right I use table 250.66 to size my cold water ground, and table 250.122 to size my conductor to the ground rod.
250.66(A) is throwng me off.

 

[dana1028]

Just checking if I am correct. This is confusing me. If I undeerstand this right I use table 250.66 to size my cold water ground, and table 250.122 to size my conductor to the ground rod.
250.66(A) is throwng me off.

No - you cannot use 250.122 for sizing any electrode conductor.

250.66(A) - says...if you leave your svc panel and go directly to the items mentioned in (A) and terminate there...ie. go no further, you do not connect to any other electrodes, then...you can use a size #6AWG conductor to connect those items listed in (A).

 

[infinity]

Table 250.66 for all GEC's and bonding jumpers. The rod conductor need not be larger than #6. 250.66(A).

 

[hotblueelectric]

Ok using tabls 250.66 I build a 200 amp resi service and my ungrounded service entrance conductors are 2/0 or 3/0 it tells me to use a #4 to the gec (ground rod) correct?

Table 250.122 tells me that my 200 amp service requires a #6 EGC to the water piping.

Im still confused

 

[jwjrw]

Ok using tabls 250.66 I build a 200 amp resi service and my ungrounded service entrance conductors are 2/0 or 3/0 it tells me to use a #4 to the gec (ground rod) correct?

Table 250.122 tells me that my 200 amp service requires a #6 EGC to the water piping.

Im still confused

I believe 250.122 is for equippment grounding not grounding electrode system.

 

[infinity]

Ok using tabls 250.66 I build a 200 amp resi service and my ungrounded service entrance conductors are 2/0 or 3/0 it tells me to use a #4 to the gec (ground rod) correct?

Table 250.122 tells me that my 200 amp service requires a #6 EGC to the water piping.

Im still confused

Take a look at post #3 again, the GEC or bonding jumper to a ground rod is never required to be larger than #6. All GEC's/bonding jumpers are sized according to Table 250.66 not Table 250.122. So for #2/0 or #3/0 Cu service entrance conductors your water pipe electrode would be a #4 Cu according to 250.66.

 

[hotblueelectric]

No - you cannot use 250.122 for sizing any electrode conductor.

250.66(A) - says...if you leave your svc panel and go directly to the items mentioned in (A) and terminate there...ie. go no further, you do not connect to any other electrodes, then...you can use a size #6AWG conductor to connect those items listed in (A).

Ok what if you continue and go to another ground rod, how do you size that conductor?

 

[infinity]

Ok what if you continue and go to another ground rod, how do you size that conductor?

It wouldn't change the requirement for a GEC or bonding jumper to not be larger than #6.

 

[hotblueelectric]

Im confused by 250.122 Isn't a 200 amp load center considered equipment?
A 200 amp service would be considered a grounded system according to 250.130 (A). Under 250.122 egc is #6. So if we go to a 300A sys why would we not use a #4. Sorry just trying to get this right.

 

[Tommy Hobbs]

I will try to say this as simple as possible,
(1) 250.66 is for grounding electrode conductor
(2) 250.122 is equipment grounding conductor
(3) Above items 1 & 2 are 2 different things
(4) 250.66 is for items pertaining to main service
(5) 250.122 is for items beyond the main service, say you are feeding a sub-
panel off of a 400 amp breaker in the main panel, then you could use a
no. 3 egc

 

[hotblueelectric]

Thanks Tommy that clears it up. (items beyond main service) Where is that found?

 

[1793]

I will try to say this as simple as possible,
(1) 250.66 is for grounding electrode conductor
(2) 250.122 is equipment grounding conductor
(3) Above items 1 & 2 are 2 different things
(4) 250.66 is for items pertaining to main service
(5) 250.122 is for items beyond the main service, say you are feeding a sub-
panel off of a 400 amp breaker in the main panel, then you could use a
no. 3 egc

Agreed. 250.66 is for the Service "Line" side and 250.122 is for the "Load" side.

 

[Volta]

Agreed. 250.66 is for the Service "Line" side and 250.122 is for the "Load" side.

Good way to say it.

 

[Tommy Hobbs]

I will not try to list all locations to help you to understand, but look at the following,

(1) article 100 - definitions
(1) grounding conductor, equipment
(2) grounding electrode conductor

(2) article 250 - grounding and bonding ( from front to rear, actually )
(1) Part I
(2) Part II
(3) Part III
(4) Part IV
(5) Part V
(4) Part VI
(8) Part VII

(3) All the above should help you understand it better

 

[hotblueelectric]

thank you all as always, you guys are great at helping our trade out, and in understanding the NEC