GROUND WIRE SIZE FOR 100 AMP SERVICE INSTALL

It is very common in this area to not see any of the four used in residential wiring and only a single rod is normally used.Īrticle 250 is very complex and it takes a lot of reading and discussion to understand it. Made and other electrodes are only to be used where none of the four specifed are not available. The latest copy I have here at my house is a 1981 copy and in 250-81 for grounding electrode system there are four different means of obtaining a system and if they are 'available' they are to be used. I know in the 2003 there were some changes made to the grounding electrode system section. I do not have a copy of the 99 NEC here at my house it is at work.

I do not know what you mean by two ground rods.

GROUND WIRE SIZE FOR 100 AMP SERVICE INSTALL

Now you will install the bonding jumper that came with your panel.Īs per table 250-66 you will need to install a #4 copper conductor to your grounding electrode system. Discard it.įrom your 200 amp feeder panel to the main you will install a neutral and equipment ground wire and they will connect to the neutral bar in the main. Do not connect the bonding jumper that comes with these panels. The nuetral bar in each feeder panel is to be isolated. All of the equipment grounding conductors coming in your branch circuit cables will go to this. Both of the sub-panels will require a seperate ground bar that is attached directly to the panel. In your case the 200 amp feeder would require a #6 copper grounding conductor and the 100 amp would require a #8 copper grounding conductor. 250-122 is based on the size of the overcurrent device protecting the circuit. As you will notice 250-66 is based on largest service entrance conductor or equivalent area for parallel conductors. Table 250-122 is for sizing equipment grounding conductors. Roy, Table 250-66 is for sizing your grounding electrode conductor which is specifically for service entrance. I have an indoor sub panel (100A) in the garage, being fed off a 100A DP breaker in the outdoor load center. I have an indoor sub panel (200A) fed thru the feed thru lugs on the outdoor load center the disconnect for it is the main breaker on the outdoor load center. I have an outdoor load center (200A) with feed thru lugs, its being used as the main panel. Thanks in advance, these two tables somewhat confused me even after reading the sub sections after and before them.

This table would be used to calculate the gauge I would need for both sub panels? If this were true then my 200A sub panel would need a #6 copper or #4 aluminum ground wire, and my 100A sub panel would need a #8 copper or #6 aluminum ground wire? Using table 250-122 Minimum Size Equipment Ground Conductors for Grounding Raceway and Equipment. Using table 250-66 GEC for Alternating Current System, I’ve come up with that the conductor from my outdoor load center (200A) to the two ground rods would have to be #4 copper or #2 aluminum because my largest service conductor is 2/0 copper? Also is this table only used to calculate the GEC going to the ground rod, this would not calculate the ground wire gauge going to my sub panels? I have an indoor sub panel (100A) in the garage, being fed off a 100A DP breaker in the outdoor load center.I have an indoor sub panel (200A) fed thru the feed thru lugs on the outdoor load center the disconnect for it is the main breaker on the outdoor load center.I have an outdoor load center (200A) with feed thru lugs, its being used as the main panel.By the way I’m using NEC 1999 edition (My County has not gone to a different edition yet). This is what I’ve interpreted it as, am I correct? Or am I looking at this all wrong. I’m somewhat confused with my interpretation of the two different ground tables in the NEC. I’m trying to size my GEC and my ground wire to my sub panels.

Ground wire size for 100 amp service