Question about Bonding Structural steel
- Thread starter JJWalecka
- Start date
- Status
- Location
- Massachusetts
Re: Question about Bonding Structural steel
No to what?
milwaukeesteve
Senior Member
- Location
- Milwaukee, WI
Re: Question about Bonding Structural steel
This reply does not address the building steel aspect, rather the GE and GEC connections referenced by AllenWayne.
The GEC must be continuous from electrode back to Main. If there are several electrodes utilized in the building, they all can be serviced by one GEC, but that GEC must remain continuous through all connections.
Bonding jumpers are different. They can be tapped off of the GEC, the main panel, or an electrode.
For example, the conductor to the ground rod is your GEC. If you add a ground rod or two, they supplement the GE (ground rod). The conductor between them is a jumper.
You cannot however "jumper" this same way over to building steel from that ground rod, because that wire is not a jumper, but a GEC, and must be continuous.
Note: bonding interior water system (due to PVC from street) and grounding an electrode (metal water pipe from street) are also different conductors; one is a jumper and one is a GEC.
[ April 04, 2005, 05:28 PM: Message edited by: milwaukeesteve ]
This reply does not address the building steel aspect, rather the GE and GEC connections referenced by AllenWayne.
The GEC must be continuous from electrode back to Main. If there are several electrodes utilized in the building, they all can be serviced by one GEC, but that GEC must remain continuous through all connections.
Bonding jumpers are different. They can be tapped off of the GEC, the main panel, or an electrode.
For example, the conductor to the ground rod is your GEC. If you add a ground rod or two, they supplement the GE (ground rod). The conductor between them is a jumper.
You cannot however "jumper" this same way over to building steel from that ground rod, because that wire is not a jumper, but a GEC, and must be continuous.
Note: bonding interior water system (due to PVC from street) and grounding an electrode (metal water pipe from street) are also different conductors; one is a jumper and one is a GEC.
[ April 04, 2005, 05:28 PM: Message edited by: milwaukeesteve ]
Re: Question about Bonding Structural steel
Steve,
See the graphic below, Iwire has posted a similar graphic from the handbook in past threads.
Roger
[ April 04, 2005, 06:23 PM: Message edited by: roger ]
Steve,
the GEC only has to hit one part of the GES, everything else that must be used if available, can be joined with "bonding jumpers", this would include building steel or what have you.
See the graphic below, Iwire has posted a similar graphic from the handbook in past threads.
Roger
[ April 04, 2005, 06:23 PM: Message edited by: roger ]
- Location
- Massachusetts
Re: Question about Bonding Structural steel
That would be this one.
shortcircuit2
Senior Member
- Location
- South of Bawstin
Re: Question about Bonding Structural steel
Notice how every picture of a grounding electrode system posted shows the GEC hitting the water pipe electrode first...all others are jumpers.
Now...used to be that the water pipe electrode was to be used first over all other electrodes because of its low resistance connection to earth...
1935 NEC section 907..."A continuous metallic underground water piping system shall always be used as the grounding electrode where such piping system is available."
Times have changed though...but wouldn't a direct run to the water pipe electrode still offer lower impedance conductive path to earth than bonding through the building's metal frame?
Jus thinking out loud...
shortcircuit2
Notice how every picture of a grounding electrode system posted shows the GEC hitting the water pipe electrode first...all others are jumpers.
Now...used to be that the water pipe electrode was to be used first over all other electrodes because of its low resistance connection to earth...
1935 NEC section 907..."A continuous metallic underground water piping system shall always be used as the grounding electrode where such piping system is available."
Times have changed though...but wouldn't a direct run to the water pipe electrode still offer lower impedance conductive path to earth than bonding through the building's metal frame?
Jus thinking out loud...
shortcircuit2
jwelectric
Senior Member
- Location
- North Carolina
Re: Question about Bonding Structural steel
Here is a picture that shows things being done a little different. I agree that earlier codes required that conductor be continuous but these are days gone by. Some of the earlier codes required the equipment grounding conductor for a pool light be continuous but there was that junction box placed under the diving board that kept getting in the way.
Here is a picture that shows things being done a little different. I agree that earlier codes required that conductor be continuous but these are days gone by. Some of the earlier codes required the equipment grounding conductor for a pool light be continuous but there was that junction box placed under the diving board that kept getting in the way.
- Location
- Massachusetts
Re: Question about Bonding Structural steel
We must always use the electrodes that are available.
There is no 'preferred' electrode in the current NEC or any of the NECs that I have worked under.
I can put a 4000 amp service out in a field and the only electrodes would be one or two ground rods connected with 6 AWG copper.
A grounding electrode does little at the voltages we work with.
Say you have a grounding electrode system that the total resistance to ground is only 10 ohms. (the code 'suggests' 25 is low enough)
Now imagine a fault to ground on a 240/120 service.
At most the current on the GEC would be 12 amps, not even enough to trip a 15 amp breaker.
And that is not taking into account the resistance of the utility grounding electrodes.
Bob
Edit; By the way shortcircuit2 I know you are just interested in doing a good job.
[ April 05, 2005, 06:06 AM: Message edited by: iwire ]
I do not see that the 1935 rule is any different than today.
We must always use the electrodes that are available.
There is no 'preferred' electrode in the current NEC or any of the NECs that I have worked under.
I can put a 4000 amp service out in a field and the only electrodes would be one or two ground rods connected with 6 AWG copper.
A grounding electrode does little at the voltages we work with.
Say you have a grounding electrode system that the total resistance to ground is only 10 ohms. (the code 'suggests' 25 is low enough)
Now imagine a fault to ground on a 240/120 service.
At most the current on the GEC would be 12 amps, not even enough to trip a 15 amp breaker.
And that is not taking into account the resistance of the utility grounding electrodes.
Bob
Edit; By the way shortcircuit2 I know you are just interested in doing a good job.
[ April 05, 2005, 06:06 AM: Message edited by: iwire ]
milwaukeesteve
Senior Member
- Location
- Milwaukee, WI
Re: Question about Bonding Structural steel
I am confused....
250.53 Grounding electrode SYSTEM installation
In this section, paragraph (C) it tells you what to do if a bonding jumper is used to connect the electrodes together.
But,
250.64 Grounding electrode conductor INSTALLATION
In this section, paragraph (C) states that the GEC shall be continuous, and in paragraph (F)To Electrode(s), it states that a GEC is permitted to be ran to any electrode OR to one or more individually (I can run one GEC for several electrodes or one GEC for each).
Therefore,
When I compare the two sections, I read it this way: when running GEC to the electrodes, I need to follow 250.64 and make them continuous(whether I run one or several GEC's.
Yet, 250.53 tells me what to do when I use a Bonding Jumper between electrodes.
However,
My only hang up with 250.53 is that it doesn't say I can use bonding jumpers in this fashion, it just tells me what to do if I use a bonding jumper.
Besides,
250.53 (B) describes the spacing requirements for made electrodes. It then states that when two or more of these made electrodes are bonded, they are considered one electrode.
(this is where I see it is fine to add more acorns and 'jumper' to your ground rods for additional rods, but only for 'made' electrodes)
Although,
250.50 states that all available electrodes shall be bonded together.
And,
250.53(D) states that when supplementing the underground water pipe electrode, that the supplemental electrode may be bonded at any convenient point.
Consequently,
I am still confused
Roger, IWire, I know what that drawing shows. I just have a problem with how I read things with all the shalls and shall nots. I haven't seen where it says what the picture shows. Let me know if I am missing something, please.
Thank you.
I am confused....
250.53 Grounding electrode SYSTEM installation
In this section, paragraph (C) it tells you what to do if a bonding jumper is used to connect the electrodes together.
But,
250.64 Grounding electrode conductor INSTALLATION
In this section, paragraph (C) states that the GEC shall be continuous, and in paragraph (F)To Electrode(s), it states that a GEC is permitted to be ran to any electrode OR to one or more individually (I can run one GEC for several electrodes or one GEC for each).
Therefore,
When I compare the two sections, I read it this way: when running GEC to the electrodes, I need to follow 250.64 and make them continuous(whether I run one or several GEC's.
Yet, 250.53 tells me what to do when I use a Bonding Jumper between electrodes.
However,
My only hang up with 250.53 is that it doesn't say I can use bonding jumpers in this fashion, it just tells me what to do if I use a bonding jumper.
Besides,
250.53 (B) describes the spacing requirements for made electrodes. It then states that when two or more of these made electrodes are bonded, they are considered one electrode.
(this is where I see it is fine to add more acorns and 'jumper' to your ground rods for additional rods, but only for 'made' electrodes)
Although,
250.50 states that all available electrodes shall be bonded together.
And,
250.53(D) states that when supplementing the underground water pipe electrode, that the supplemental electrode may be bonded at any convenient point.
Consequently,
I am still confused
Roger, IWire, I know what that drawing shows. I just have a problem with how I read things with all the shalls and shall nots. I haven't seen where it says what the picture shows. Let me know if I am missing something, please.
Thank you.
Re: Question about Bonding Structural steel
Steve, let's simplify this. When we bond all the items in 250.52(A)(1) through (A)(6) we have one Grounding Electrode System and the GEC must be continuous (per 250.64(C) to any one convenient point of this system which complys with 250.64(F).
If you choose to, you can make it a continuous conductor, but the portion of this conductor that would be considered the GEC is the portion of the conductor from the Neutral grounding point to the first point of connection to the GES.
Roger
[ April 05, 2005, 12:09 PM: Message edited by: roger ]
Steve, let's simplify this. When we bond all the items in 250.52(A)(1) through (A)(6) we have one Grounding Electrode System and the GEC must be continuous (per 250.64(C) to any one convenient point of this system which complys with 250.64(F).
If you choose to, you can make it a continuous conductor, but the portion of this conductor that would be considered the GEC is the portion of the conductor from the Neutral grounding point to the first point of connection to the GES.
Roger
[ April 05, 2005, 12:09 PM: Message edited by: roger ]
milwaukeesteve
Senior Member
- Location
- Milwaukee, WI
Re: Question about Bonding Structural steel
Hey Roger,
I guess I do see that 250.64(F) states that the GEC can be ran to ANY convenient electrode in the SYSTEM. (read this section differently before)
And 250.50 states that available electrodes shall be bonded together to form that SYSTEM.
I was looking at this only in terms of the Grounding Electrodes and the Grounding Electrode Conductors, and not looking at this as a Grounding Electrode System.
Thank you,
Steve
Hey Roger,
I guess I do see that 250.64(F) states that the GEC can be ran to ANY convenient electrode in the SYSTEM. (read this section differently before)
And 250.50 states that available electrodes shall be bonded together to form that SYSTEM.
I was looking at this only in terms of the Grounding Electrodes and the Grounding Electrode Conductors, and not looking at this as a Grounding Electrode System.
Thank you,
Steve
Re: Question about Bonding Structural steel
Even in places where water services are REQUIRED to be in metal pipe, it still is not necessarily the kind of ground that you think that it is:
1. The outside of the water main is painted with insulated paint to reduce corrosion form the outside.
2. The corporation stop that is used to tap the main is usually installed with rather thick and insulating thread dope.
3. Some water companies such as Canton, Ohio deliberately install a dielectric union in between the main and the service lateral so that the water main cannot serve as a ground bus. One electrical inspector told me about an 8 unit condominium with an 8 meter electrical service and individual water services for each unit. He had to make the EC run 2/0 copper from the electrical service to the last water service unbroken. The electrical inspector had to make the EC put in 7 crimped taps for the other 7 water services because the water company installs dielectric unions at the water main.
[ April 06, 2005, 02:03 AM: Message edited by: mc5w ]
Even in places where water services are REQUIRED to be in metal pipe, it still is not necessarily the kind of ground that you think that it is:
1. The outside of the water main is painted with insulated paint to reduce corrosion form the outside.
2. The corporation stop that is used to tap the main is usually installed with rather thick and insulating thread dope.
3. Some water companies such as Canton, Ohio deliberately install a dielectric union in between the main and the service lateral so that the water main cannot serve as a ground bus. One electrical inspector told me about an 8 unit condominium with an 8 meter electrical service and individual water services for each unit. He had to make the EC run 2/0 copper from the electrical service to the last water service unbroken. The electrical inspector had to make the EC put in 7 crimped taps for the other 7 water services because the water company installs dielectric unions at the water main.
[ April 06, 2005, 02:03 AM: Message edited by: mc5w ]
- Status