Generator question

[jl4182]

I am working on a building that has a 300 amp single phase service. After the meter the service is tapped in a trough with Polaris lugs going out to multiple panels. Directly after the meter, the neutral is bonded. Someone installed two separate backup generators on the building. I was called to figure out why lights keep burning out in building. I found that only flourescents with thermal overload ballasts were failing. When I opened the panels that were covered by backup generators, I found that the neutral bonds in those panels had been removed. I know this is standard procedure, but when you touch neutral to ground, it creates a humming sound. I found there to be no shorts in the building. When I went to the transfer switches, I found they had a neutral bonding jumper in each ATS. I am thinking this is a neutral problem. After looking up the specific models of generators, I found that the installation instructions show only one bonding jumper which should be in ATS. Finally, here is my question. Should I remove the bonding jumpers in the transfer switches or the bond after the meter? Or am I way off base? I appreciate any insight.

 

[ActionDave]

Finally, here is my question. Should I remove the bonding jumpers in the transfer switches or the bond after the meter?

I read and re-read your description and to be honest I don't know for sure. If the transfer switch is also the service disconnect then the bond stays there. If the the transfer switch comes after the service disconnect then the switch treated just like a sub-panel and wired accordingly.

Or am I way off base? I appreciate any insight.

While you may have some improper neutral bonding issues I can't see how that would make ballasts go bad.

 

[iceworm]

I am working on a building that has a 300 amp single phase service. After the meter the service is tapped in a trough with Polaris lugs going out to multiple panels. Directly after the meter, the neutral is bonded. Someone installed two separate backup generators on the building. I was called to figure out why lights keep burning out in building. I found that only flourescents with thermal overload ballasts were failing. When I opened the panels that were covered by backup generators, I found that the neutral bonds in those panels had been removed. I know this is standard procedure, but when you touch neutral to ground, it creates a humming sound. I found there to be no shorts in the building. When I went to the transfer switches, I found they had a neutral bonding jumper in each ATS. I am thinking this is a neutral problem. After looking up the specific models of generators, I found that the installation instructions show only one bonding jumper which should be in ATS. Finally, here is my question. Should I remove the bonding jumpers in the transfer switches or the bond after the meter? Or am I way off base? I appreciate any insight.

I read and re-read your description and to be honest I don't know for sure. ... While you may have some improper neutral bonding issues I can't see how that would make ballasts go bad.

I got to agree with Dave here. I'm not seeing the connection. So, is it the ballasts with the thermal overloads that are failing? The bulbs and non-thermally protected ballasts are working fine?
Qs:
Are the non-thermally protected ballasts running hotter than normal?
Are they connected to a different transformer?
Is the voltage different?
Are they drawing more/less current than comparable thermally protected ballasts?

Also agreeing with Dave, the plant has issues with Separately Derive Systems and NG bonding.

Do you have access to any one-lines? And I'm guessing no engineering staff?

Just curious:
Does the backup generation cover the whole plant or or just selected sections?
A 72KVA, single phase service (120/240?) is small. Definitely not industrial. Likely no motors other small (<5hp) HVAC
I'm guessing the generation is small, likely no more than 20kw - 50kw each.

Generally speaking, for every different configuration (generator\service line-up) there should be only one N-G bond. You will need to look at if the ATS are 2W or 3W (is the neutral switched). You will really need to put together a good one-line.

ice

 

[rlundsrud]

You are saying that the neutrals are bonded both after the meter and at the transfer switches? they shouldn't be bonded at both points, only at the first disconnect. This is also where the GEC should terminate. Although if I am undestanding this, it is incorrect, I don't believe it would cause these ballasts to fail, it would however create undesirable currents in the EGC. I hope that helps.

 

[augie47]

Lets look at the "lights burning out problem"...
What is failing, the lamps or the ballasts ?
Can you give the details... such as lamp and ballast catalog numbers ?
Have you taken voltage readings on the lighting circuits both with and without the generators running ?


Without a one line diagram and a lot more info it's difficult to give advice on the "grounding".
IF the service conductors from the wireway go directly into the transfer switches then in all probability there would be a neutral-grounding bond there and the neutrals & grounding conductors would be separated in your downstream panels.
The "humming" is of some interest... You state the neutral bonds in the panels have been removed. What method is being used to assure the equipment ground bars have a return path to the neutral-ground path in the transfer switch ?