Ground testing versus no bonding

[JMC01]

If a testing firm performs a a ground test on a building and the test results are good, does that verify that the grounding electrode system and the bonding have all been done in accordance with the NEC? I know for a fact that the only grounding is a driven rod at the main service and jumper from the ground bus to the bar joist, which does not connect to other sections of building.

 

[Dennis Alwon]

IMO, the ground test can be done and show -- not so good- and the grounding can be up to NEC compliance. I don't know what good is or what bad is. If you use 25 ohms as a guide then it may be done well but it still may not be to code. All electrodes are req. to be used in the grounding. You can get a low reading and still not have connected all the electrodes together or done something not to code.

 

[brian john]

All the electrical testing firm can tell you by a test is that the electrode under test meets a certain resistance on the day of the test. Which can change with temperature, precipitation, ETC...


Now if we are hired to do a system ground inspection and test we can make those determinations.

 

[JMC01]

So, maybe I should suggest they do a complete system ground?

 

[JMC01]

that should be complete system ground test?

 

[brian john]

Ground test and inspection

 

[zog]

that should be complete system ground test?

Yes, like Brian said, "Ground test" is a little vauge. You need to know what you are requesting to be tested. However, any testing company worth squat should have asked you. 80% of real testing companies are pretty good, but there are some out there that "say" they do testing but really just do it as an added service. You want a firm that does nothing else.

You should spec this:

NETA ATS?2003
Section 7.13
Grounding Systems
1. Visual and Mechanical Inspection
1. Verify ground system is in compliance with drawings, specifications, and NFPA 70 National Electrical Code.
2. Inspect physical and mechanical condition.
3. Inspect anchorage.
2. Electrical Tests
1. Perform fall of potential or alternative test in accordance with ANSI/IEEE 81 on the main grounding electrode or system.
2. Perform point-to-point tests to determine the resistance between the main grounding system and all major electrical equipment frames, system neutral, and/or derived neutral points.
3. Test Values
1. The resistance between the main grounding electrode and ground should be no greater than five ohms for large commercial or industrial systems and 1.0 ohm or less for generating or transmission station grounds unless otherwise specified by the owner. (Reference ANSI/IEEE 142)
2. Investigate point-to-point resistance values which exceed 0.5 ohm.

 

[JMC01]

Zog,

Thanks for the info. Now, how can I prove that the simple ground test performed by the testing company does not prove that the grounding and bonding of the building is in compliance with the NEC? This guy is doing everything he can to avoid installing a GES per code because he neglected to be on the job when the building was coming out of the ground. For instance, there is no connection to a concrete encased electrode which was available (of course not now because the floor is poured), isolated structural steel for bridge cranes that are not connected to other building steel, a seperate ground rod driven at the front of the building but not connected to the main grounding system, the office structural steel is isolated from the plant steel and not bonded to anything, there is a sprinkler piping system not bonded to anything, a steel gas piping system not bonded to anything, a 75 KVA transformer that is has no bond on the XO tap, embedded rails (like train tracks) in the floor that machinery travels on not bonded to anything. I could go on and on. Of course this is the work of a guy that told us that the main bonding jumper in the switchgear was of no consequence if he had the ground bus connected to a ground rod. I am at my wits end argueing this. The local building official (which is not an electrical inspector) gave them the OK based on the fact the testing firm issued a letter stating that grounding meets code.

 

[brian john]

Ask the testing firm what exactly meets code, ask them to state in writing that all aspects of the installation meet code. Get you camera, note book and NEC out and prove what you believe to be the case.

Explain in writing to you bosses your concerns and how they really do not want to be liable for possible future issues based on current violations.

 

[JMC01]

Brian, Thanks,

I can talk till I am blue in the face. They refuse to believe me. Mainly because I am the contractor awarded the equipment wiring job and the building contractor wanted it. Do you have any idea of exactly who could make the final call on whether or not the system meets code requirements......someone that they would believe??

 

[brian john]

Brian, Thanks,

I can talk till I am blue in the face. They refuse to believe me. Mainly because I am the contractor awarded the equipment wiring job and the building contractor wanted it. Do you have any idea of exactly who could make the final call on whether or not the system meets code requirements......someone that they would believe??

The AHJ
The Design Engineer
The facility electrician.
Document your concerns and move on.

 

[zog]

Zog,

Thanks for the info. Now, how can I prove that the simple ground test performed by the testing company does not prove that the grounding and bonding of the building is in compliance with the NEC? This guy is doing everything he can to avoid installing a GES per code because he neglected to be on the job when the building was coming out of the ground. For instance, there is no connection to a concrete encased electrode which was available (of course not now because the floor is poured), isolated structural steel for bridge cranes that are not connected to other building steel, a seperate ground rod driven at the front of the building but not connected to the main grounding system, the office structural steel is isolated from the plant steel and not bonded to anything, there is a sprinkler piping system not bonded to anything, a steel gas piping system not bonded to anything, a 75 KVA transformer that is has no bond on the XO tap, embedded rails (like train tracks) in the floor that machinery travels on not bonded to anything. I could go on and on. Of course this is the work of a guy that told us that the main bonding jumper in the switchgear was of no consequence if he had the ground bus connected to a ground rod. I am at my wits end argueing this. The local building official (which is not an electrical inspector) gave them the OK based on the fact the testing firm issued a letter stating that grounding meets code.

Not sure what I can do to help you here, you obviously have issues here, but the testng firm you hired was either clueless or did not have a clear specification of what they were there to test. This is exactly why people need to use industry standards, not just request a ground test or breaker test, or "fill in the blank" test.

Maybe hire a different testing company to come check it out again? One that knows what they are doing perhaps?