Here is the situation. Pole building with 5 units. One house meter. Plastic water line feeding each unit. 600 amp overhead service. Parreled 350mcm up 2 3" pipes on service. Using the NEC, I come up with a grounding conductor size of 1 ought. Can this go to just the 5/8x8' rod, or must it be a ufer gnd, or must it tie into the footing? Also, the building is already up and it would not be possible to tie into the footing. THank you for the speedy reply in advance. Tim
600 amp service
- Thread starter tim
- Start date
- Status
- Location
- Massachusetts
Re: 600 amp service
Tim You have 2 sets of 350s I have to assume copper for this 600 amp service.
2 x 350 = 700 kcmil using table 250.66 shows us a a 2/0 grounding electrode conductor for 600 to 1100 kcmil of service conductor.
However the GEC to a ground rod is never required by the NEC to be larger than 6 AWG no matter what service size.
In this area if the Concrete encased electrode is not available we ignore it, I have heard that in NJ for instance you must use it.
The Concrete encased electrode would only need a 4 AWG.
But is there no water service to this building?
The GEC to the water pipe will need to be 2/0
Hope this helps.
Tim You have 2 sets of 350s I have to assume copper for this 600 amp service.
2 x 350 = 700 kcmil using table 250.66 shows us a a 2/0 grounding electrode conductor for 600 to 1100 kcmil of service conductor.
However the GEC to a ground rod is never required by the NEC to be larger than 6 AWG no matter what service size.
In this area if the Concrete encased electrode is not available we ignore it, I have heard that in NJ for instance you must use it.
The Concrete encased electrode would only need a 4 AWG.
But is there no water service to this building?
The GEC to the water pipe will need to be 2/0
Hope this helps.
- Location
- Massachusetts
Re: 600 amp service
Tim it sounds like you will not be running a 2/0 anywhere.
It appears you will have two ground rods with a 6 AWG running to them.
Tim it sounds like you will not be running a 2/0 anywhere.
It appears you will have two ground rods with a 6 AWG running to them.
jim sutton
Senior Member
Re: 600 amp service
Tim, the way I would interpret the (2000) code is:
1)250.50 says if available you are to use each of the 7 listed electrodes bonded together. Where none are available install one or more of electrodes 4 thru 7.
2) If you choose to install ground rods in this case it would not be a supplemental electrode as required in section 250.53(D)(2) and you would use a 2/0 copper grounding electrode conductor.
Also if you use only one rod, you will have to test it to see if it has 25ohms or less to ground or drive more than one. Per 250.56
Check 250.53(G) also
I hope this helps
Tim, the way I would interpret the (2000) code is:
1)250.50 says if available you are to use each of the 7 listed electrodes bonded together. Where none are available install one or more of electrodes 4 thru 7.
2) If you choose to install ground rods in this case it would not be a supplemental electrode as required in section 250.53(D)(2) and you would use a 2/0 copper grounding electrode conductor.
Also if you use only one rod, you will have to test it to see if it has 25ohms or less to ground or drive more than one. Per 250.56
Check 250.53(G) also
I hope this helps
- Location
- Massachusetts
Re: 600 amp service
Jim the NEC never requires larger than 6 AWG copper or 4 AWG aluminum to a ground rod.
Take a look at 250.66(A)
Jim the NEC never requires larger than 6 AWG copper or 4 AWG aluminum to a ground rod.
Take a look at 250.66(A)
jim sutton
Senior Member
Re: 600 amp service
iwire, thanks for the reply
I just don't agree. This argument has been around for a while.
250.66(A) has some strange wording: "....that portion of the conductor that is the sole connection to the grounding electrode shall not be required to be larger than 6 awg copper...."
what are they referring to when they say "that portion of the conductor"? The conductor is the same its entire length right?
I think it means exactly what it says "that portion of the conductor" not the entire length.
I know this is strange but thats what it says.
And thanks again, I learn new stuff all the time
[ December 31, 2003, 03:49 PM: Message edited by: jim sutton ]
iwire, thanks for the reply
I just don't agree. This argument has been around for a while.
250.66(A) has some strange wording: "....that portion of the conductor that is the sole connection to the grounding electrode shall not be required to be larger than 6 awg copper...."
what are they referring to when they say "that portion of the conductor"? The conductor is the same its entire length right?
I think it means exactly what it says "that portion of the conductor" not the entire length.
I know this is strange but thats what it says.
And thanks again, I learn new stuff all the time
[ December 31, 2003, 03:49 PM: Message edited by: jim sutton ]
Re: 600 amp service
Would a person then bond each plumbing system in each unit from each units panel? Also I put two rods down with #4 bare and tied them together. It passed. Thanks for the responses so far. Grounding and bonding have to be the most controversial topics when it comes to our inspectors here in central Illinois. Tim
Would a person then bond each plumbing system in each unit from each units panel? Also I put two rods down with #4 bare and tied them together. It passed. Thanks for the responses so far. Grounding and bonding have to be the most controversial topics when it comes to our inspectors here in central Illinois. Tim
jim sutton
Senior Member
Re: 600 amp service
yes, tim,
250.104(A)(2)
yes, tim,
250.104(A)(2)
- Location
- Massachusetts
Re: 600 amp service
Jim the wording in 250.66(A) is just trying to make clear that only the conductor to the rod can be 6 AWG
600 amp service in question, leave the service disconnect with 2/0 copper and go to the water pipe, from there continue to the ground rod(s) with 6 AWG. This is OK and meets code.
Leave the same service with 6 AWG go to the rod(s) from there continue to the water pipe with 2/0.
This is not OK and will not meet code.
The reason a ground rod does not require larger than 6 AWG is because the rod is itself is not able to pass enough current to need larger than 6 AWG.
A water pipe on the other hand under the right (or wrong depending on your point of view) may have to carry the full fault current of the utility transformer.
Jim the wording in 250.66(A) is just trying to make clear that only the conductor to the rod can be 6 AWG
600 amp service in question, leave the service disconnect with 2/0 copper and go to the water pipe, from there continue to the ground rod(s) with 6 AWG. This is OK and meets code.
Leave the same service with 6 AWG go to the rod(s) from there continue to the water pipe with 2/0.
This is not OK and will not meet code.
The reason a ground rod does not require larger than 6 AWG is because the rod is itself is not able to pass enough current to need larger than 6 AWG.
A water pipe on the other hand under the right (or wrong depending on your point of view) may have to carry the full fault current of the utility transformer.
jim sutton
Senior Member
Re: 600 amp service
iwire,
you said---"Jim the wording in 250.66(A) is just trying to make clear that only the conductor to the rod can be 6 AWG"
The wording stands as is, it is in plain english, no offense.
I see your point exactly, if you are talking about a GEC that loops from each of the chosen or available 7. But here we are talking about the ground rods as being the sole electrode.
I respect your position and I have heard this before.you said--"The reason a ground rod does not require larger than 6 AWG is because the rod is itself is not able to pass enough current to need larger than 6 AWG."
Electricians are not required to be engineers, is the above statement in the NEC somewhere?
you said--"600 amp service in question, leave the service disconnect with 2/0 copper and go to the water pipe, from there continue to the ground rod(s) with 6 AWG. This is OK and meets code."
this is not the case here, he has plastic feeding the building, the rods are his only grounding electrode.
Most if not all plans that I have seen from engineers require the GEC to be sized per 250.66 and cadwelded to ground rods.
On my small jobs that are not engineered, I am not going to run a no. 6 as the only GEC just by someone elses interpretation.
If I am missing something here, please correct me! Back up your comments with code sections.
iwire,
you said---"Jim the wording in 250.66(A) is just trying to make clear that only the conductor to the rod can be 6 AWG"
The wording stands as is, it is in plain english, no offense.
I see your point exactly, if you are talking about a GEC that loops from each of the chosen or available 7. But here we are talking about the ground rods as being the sole electrode.
I respect your position and I have heard this before.you said--"The reason a ground rod does not require larger than 6 AWG is because the rod is itself is not able to pass enough current to need larger than 6 AWG."
Electricians are not required to be engineers, is the above statement in the NEC somewhere?
you said--"600 amp service in question, leave the service disconnect with 2/0 copper and go to the water pipe, from there continue to the ground rod(s) with 6 AWG. This is OK and meets code."
this is not the case here, he has plastic feeding the building, the rods are his only grounding electrode.
Most if not all plans that I have seen from engineers require the GEC to be sized per 250.66 and cadwelded to ground rods.
On my small jobs that are not engineered, I am not going to run a no. 6 as the only GEC just by someone elses interpretation.
If I am missing something here, please correct me! Back up your comments with code sections.
- Location
- Massachusetts
Re: 600 amp service
Jim the only relevant code section is 250.66(A)
If you have access to the 2002 NEC handbook you can see a great illustration of what I am talking about.
Exhibit 250.29 Grounding electrode conductor and bonding jumpers sized in accordance with 250.66 for a service supplied by 3/0 AWG ungrounded conductors.
Jim the only relevant code section is 250.66(A)
If you have access to the 2002 NEC handbook you can see a great illustration of what I am talking about.
Exhibit 250.29 Grounding electrode conductor and bonding jumpers sized in accordance with 250.66 for a service supplied by 3/0 AWG ungrounded conductors.
jim sutton
Senior Member
Re: 600 amp service
Iwire,
I dont have a 2000 handbook, I do have a 99 handbook.
I am looking in it to find referenced illustration.
I see your point but, the only thing I see that tells you that a #6 is OK refers to supplemental rods.
In this case the rods are not supplemental, they are the sole electrode.
Iwire,
I dont have a 2000 handbook, I do have a 99 handbook.
I am looking in it to find referenced illustration.
I see your point but, the only thing I see that tells you that a #6 is OK refers to supplemental rods.
In this case the rods are not supplemental, they are the sole electrode.
- Location
- Massachusetts
Re: 600 amp service
Jim feel free to call me Bob, I do not have the 99 book so we can not compare, but going back to 250.66(A) it makes no distention between a sole electrode and a supplementary one.
If we say it applies to a supplementary one, which is there in case the water pipe one is lost, if the water pipe one is lost it is now the sole electrode.
Why then would it make a difference if it is the sole or supplementary electrode?
This is not a real reference but I install a good deal of large temporary services for our jobs.
600, 800, 1200 amps 480 3 phase temp services, the only grounding electrode is typically two ground rods run with 6 AWG.
I work for a professional, safety conscious, large company in states with NEC adoption and inspections, never do the inspectors question this 6 AWG to a rod.
Jim feel free to call me Bob, I do not have the 99 book so we can not compare, but going back to 250.66(A) it makes no distention between a sole electrode and a supplementary one.
If we say it applies to a supplementary one, which is there in case the water pipe one is lost, if the water pipe one is lost it is now the sole electrode.
Why then would it make a difference if it is the sole or supplementary electrode?
This is not a real reference but I install a good deal of large temporary services for our jobs.
600, 800, 1200 amps 480 3 phase temp services, the only grounding electrode is typically two ground rods run with 6 AWG.
I work for a professional, safety conscious, large company in states with NEC adoption and inspections, never do the inspectors question this 6 AWG to a rod.
jim sutton
Senior Member
Re: 600 amp service
Bob, thanks for the reply.
You are right, there is no distinction in 250-66A
My problem is with the wording of the section: "....that portion of the conductor "
I have 2 plans to bid on the table, both have fully sized GEC's to the rods.
Thanks again, Happy New Year
Bob, thanks for the reply.
You are right, there is no distinction in 250-66A
My problem is with the wording of the section: "....that portion of the conductor "
I have 2 plans to bid on the table, both have fully sized GEC's to the rods.
Thanks again, Happy New Year
- Location
- Massachusetts
Re: 600 amp service
The POCO around here many times wants 4/0 cad welded to the rods around a transformer pad.
Happy New Year, Bob
That is why I have been careful to say the NEC does not require it.
The POCO around here many times wants 4/0 cad welded to the rods around a transformer pad.
Happy New Year, Bob
russ
Senior Member
- Location
- Burbank IL
Re: 600 amp service
I didn't give this much thought before, because where I live their's almost always a water pipe.
Before reading a comment in the hand book I would have agreed with Bob.
1999 HB 250-66 a light blue section right after (c) Connections to ground rings.
(small section of paragraph)
"If the grounding electrode conductor from the service equipment were run, for example, to the ground rod first and then to the water pipe, the conductor to the ground rod would also have to be full sized, per Table 250.66."
There does seem to be a wording clarification needed. Depending which way you tilt your head it can look different.
[ December 31, 2003, 06:34 PM: Message edited by: russ ]
I didn't give this much thought before, because where I live their's almost always a water pipe.
Before reading a comment in the hand book I would have agreed with Bob.
1999 HB 250-66 a light blue section right after (c) Connections to ground rings.
(small section of paragraph)
"If the grounding electrode conductor from the service equipment were run, for example, to the ground rod first and then to the water pipe, the conductor to the ground rod would also have to be full sized, per Table 250.66."
There does seem to be a wording clarification needed. Depending which way you tilt your head it can look different.
[ December 31, 2003, 06:34 PM: Message edited by: russ ]
A
a.wayne3@verizon.net
Guest
Re: 600 amp service
Tim i just got in and recieved your email,anyway as I look at it depending upon the inspector we all know its their interpetation as long as they can substantiate it with reason.As far as 600 amp services go I go by the incoming feeder sizing table.That`s the max needed by any articles.Yeah you can pick the nec apart and find other articles that say otherwise but as long as what is it 250.66 lists ,don`t have my book here.Says that a larger size grounding conductor is required I go with that.I`m sure this will open some doors
Tim i just got in and recieved your email,anyway as I look at it depending upon the inspector we all know its their interpetation as long as they can substantiate it with reason.As far as 600 amp services go I go by the incoming feeder sizing table.That`s the max needed by any articles.Yeah you can pick the nec apart and find other articles that say otherwise but as long as what is it 250.66 lists ,don`t have my book here.Says that a larger size grounding conductor is required I go with that.I`m sure this will open some doors
A
a.wayne3@verizon.net
Guest
Re: 600 amp service
Oh I forgot about the footer bonding....Duhhhh
If the ufer was not done and/or inspected the NEC says a ditch 30 inches deep and 20 ft long with the ground wire in it.Here the AHJ wants ground rods with it but for a 200 amp service the NEC requires a # 2 wire so do you double the sizing acoordingly to the the amperage of the service???
Oh I forgot about the footer bonding....Duhhhh
If the ufer was not done and/or inspected the NEC says a ditch 30 inches deep and 20 ft long with the ground wire in it.Here the AHJ wants ground rods with it but for a 200 amp service the NEC requires a # 2 wire so do you double the sizing acoordingly to the the amperage of the service???
Re: 600 amp service
Wants again, I say thank you to all the responces so far. There sure are not any clear cut answers here. That is between you all, LOL. Hope to see some more opinions. I think grounding and bonding are very important and that is why everyone is so compasionate on the topic. Have a very safe and happy New Year. Tim Hausmann.
Wants again, I say thank you to all the responces so far. There sure are not any clear cut answers here. That is between you all, LOL. Hope to see some more opinions. I think grounding and bonding are very important and that is why everyone is so compasionate on the topic. Have a very safe and happy New Year. Tim Hausmann.
- Status