Three Separate Buildiings. NEC 250.32 and Bonding Questions

[well grounded in Kansas]

I started a thread last year that is now closed regarding a site with three separate buildings and getting power from one 1600 amp three phase panel feeding the other buildings. (3 phase Wye) The thread was Three Phase Site with Multiple Issues. And the issues still remain.

The site has ballast go out on a regular basis, low voltage lights burn out simultaneously, Arc Fault breakers trip regularly, PTAC (HVAC units) thermostats burn up and regular issues with low voltage systems like the fire alarm. Emergency lights activate when no power failure seems apparent. Last week a worker changing a light fixture was "zapped" when he touched the white neutral.

A EC has said the site meets code so we are not the repair team, but have found things the repair team misses. We found that the spec required all branch circuits to have their own neutral and that was not done. Neutrals are shared in the field. Building 2 has the main disconnect and is feed by the Utility. That building started out only having two ground rods. No Ufer or water pipe. A second GES was installed having three rods bonded and laid in a straight line and added to the existing ground buss. The other buildings, 1 and 3 do not have a GES and that would appear to be a code violation (250.32) and is not to spec/drawings which detail them. The disconnect at 1 and 3 have the ground wires from building 2 only. So there is a ground, just not one of their own. A Entech (382357) clamp on ground resistance tester at building 1 and 3 had to much noise to provide a reliable reading. Building 2 did have a good ground reading, but with five rods that stands to reason.

My questions are:
1) Has anyone seen similar electrical system anomalies when separate buildings are not grounded in accordance with NEC 250.32?
2) The building domestic water is fed by non metallic pipe so no water pipe ground is available (or needed), but the sprinkler riser is 6" metal. Should it be connected to the grounding system? It can't be used as a "ground system", but I believe it should be connected.
3) This site also has a Kohler Generator and we need to have a generator tech look at the connections. It may have ground and neutral bonded at the gen set. The transfer switch is good and no load side bond is inside it. The question is for someone familiar with generator wiring. Is ground and neutral connected together at the generator when the transfer switch only changes the three phases?

Thanks for any feedback.

 

[augie47]

My questions are:
1) Has anyone seen similar electrical system anomalies when separate buildings are not grounded in accordance with NEC 250.32?

I am not convinced that the anomalies you describe would have much realtion to the grounded electrode system, but thats just an opinion. I would probably be more concerned about a loose grounded conductor connection

2) The building domestic water is fed by non metallic pipe so no water pipe ground is available (or needed), but the sprinkler riser is 6" metal. Should it be connected to the grounding system? It can't be used as a "ground system", but I believe it should be connected.

The sprinkler codes do not allow sprinkler wiring to serve as grounds.

3) This site also has a Kohler Generator and we need to have a generator tech look at the connections. It may have ground and neutral bonded at the gen set. The transfer switch is good and no load side bond is inside it. The question is for someone familiar with generator wiring. Is ground and neutral connected together at the generator when the transfer switch only changes the three phases?

Thanks for any feedback.

If the transfer switch does not switch the neutral, there should be no neutral (grounded) to grounding connection at the generator. You should have both a grounded and grounding conductor at the generator but they should not be connected.

 

[Sparky3141]

The site has ballast go out on a regular basis, low voltage lights burn out simultaneously, Arc Fault breakers trip regularly, PTAC (HVAC units) thermostats burn up and regular issues with low voltage systems like the fire alarm. Emergency lights activate when no power failure seems apparent. Last week a worker changing a light fixture was "zapped" when he touched the white.

Sounds like you might be having some power quality issues. Might want to invest in some monitoring equipment. Your lack of earth grounding at your sub-panels aren't going to cause whacky power problems. Maybe a good exorcism.... :::grimace:::


Sent from my iPhone using Tapatalk

 

[well grounded in Kansas]

Power Quality was done

Power Quality was done

The site invested in a power quality study by Emerson and it did show a few occasions of Current Harmonics in the 20% range and routinely hitting 15%. During the three week study not one issue was observed. The neutral did have higher than expected current and Emerson said it was due to the unbalanced load and harmonics, (obvious) but not anything to be concerned with. The voltage range was as low as 97 and as high as 127 if I recall. The 97 was momentary. I used a logging Fluke and recorded lows in the 106 range and highs near 130VAC.

 

[well grounded in Kansas]

Am I wrong?

Am I wrong?

I am not convinced that the anomalies you describe would have much realtion to the grounded electrode system, but thats just an opinion. I would probably be more concerned about a loose grounded conductor connection


The sprinkler codes do not allow sprinkler wiring to serve as grounds.


If the transfer switch does not switch the neutral, there should be no neutral (grounded) to grounding connection at the generator. You should have both a grounded and grounding conductor at the generator but they should not be connected.

The Electrical Contractor installed GES (Ground Rods) in the two separate buildings and disconnected the ground from the main service at the detached building and also then bonded the Neutral and Grounds in the two separate buildings. So, to paint a better picture; Building 2 has a the main 1600 amp service that feeds disconnects for all three buildings. Through PVC pipe to Buildings 1 and 3 they initially ran ground wires to the main 600 amp disconnect in Buildings 1 and 3 and connected to the ground bar, but no bond to neutral. Since NEC 250.32 states all separate (new) buildings shall have their own ground, they added them today. But, they removed the interconnecting ground and added Neutral and Ground bonds in Buildings 1 and 3. Does that sound right?

 

[augie47]

The Electrical Contractor installed GES (Ground Rods) in the two separate buildings and disconnected the ground from the main service at the detached building and also then bonded the Neutral and Grounds in the two separate buildings. So, to paint a better picture; Building 2 has a the main 1600 amp service that feeds disconnects for all three buildings. Through PVC pipe to Buildings 1 and 3 they initially ran ground wires to the main 600 amp disconnect in Buildings 1 and 3 and connected to the ground bar, but no bond to neutral. Since NEC 250.32 states all separate (new) buildings shall have their own ground, they added them today. But, they removed the interconnecting ground and added Neutral and Ground bonds in Buildings 1 and 3. Does that sound right?

It does not sound correct. Building 1 & 3 should have a equipment grounding conductor from Building 2. A Grounding Electrode System should be established at Buildings 1 & 3 with a grounding electrode conductor connected to the equipment grounding buss along with the panel bond. There should be no neutral to grounding connection at those two buildings.

 

[well grounded in Kansas]

Thanks for the quick reply.

Thanks for the quick reply.

It does not sound correct. Building 1 & 3 should have a equipment grounding conductor from Building 2. A Grounding Electrode System should be established at Buildings 1 & 3 with a grounding electrode conductor connected to the equipment grounding buss along with the panel bond. There should be no neutral to grounding connection at those two buildings.

That's exactly what I thought.