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Discussion Starter · #1 ·
Have a residential 120/240 service previously was a house that got remodeled in to a small office like building old existing pnl was replaced with a new simens pnl and new circuits were ran. One of the new lighting circuits contains about 12 Comercial florescent R.C. Cans. The customer claims that through out the day the cans will very slowly dim and then slowly come back to 100% according to them some of the cans will dim down faster and some will also come back to 100% faster. Now all these cans are brand new the bulbs are brand new they are on regular C.R. Toggle switches all these lights are on one dedicated circuit with no other loads on the circuit, there are also 3 emergency ballasts wired in to 3 of the cans that do test fine. So far the following has been done / checked and still the same problem.
1. All of the connections from the C.B. to all and in all the cans have double checked.
2. All circuit breakers in the pnl have been pulled out and the buss and all breakers inspected.
3. The voltages at the pnl are all good to neutral and P to P.
4. Everything in the pnl has been tightened down.
5. On this 200a service they are on the average only using about 30ish amps per leg.
6. All of the ballasts in all of the cans have been changed out for brand new.
7. The circuit has been moved to a different circuit breaker and from A to B.
Usually according to the customer the whole dimming down to back up to 100% happens over a 2hrish period of them dimming slowly and brightening back up slowly to full brightness. Any ideas to why this is happening
 

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Ditch Digging Dummy
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It could be demand being utilized from the poco. When peak demand hits, small (but noticeable) voltage drop can be seen throughout periods of the day. I had a similar problem with a customers lighting with incandescent fixtures that would dim down.
 

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Have a residential 120/240 service previously was a house that got remodeled in to a small office like building old existing pnl was replaced with a new simens pnl and new circuits were ran.
Been in a similar situation about three years ago. *sigh*. We ended up changing every damn breaker unfortunately.

One of the new lighting circuits contains about 12 Comercial florescent R.C. Cans. The customer claims that through out the day the cans will very slowly dim and then slowly come back to 100% according to them some of the cans will dim down faster and some will also come back to 100% faster. Now all these cans are brand new the bulbs are brand new they are on regular C.R. Toggle switches all these lights are on one dedicated circuit with no other loads on the circuit, there are also 3 emergency ballasts wired in to 3 of the cans that do test fine.
It has to detect a fault condition in the low-voltage wiring within the breaker enclosure. When there is that much load you have to be cautious. I've lost many breakers that way unfortunately. Had to get a whole bunch of replacements for new circuit breakers. For large currents or high voltages are usually arranged with pilot devices to sense a fault current and to operate the trip opening mechanism. The trip solenoid that releases the latch is usually energized by a separate battery.

So far the following has been done / checked and still the same problem.
1. All of the connections from the C.B. to all and in all the cans have double checked.
Did you ensure you cleaned the wiring with isopropyl alcohol?

2. All circuit breakers in the pnl have been pulled out and the buss and all breakers inspected.
3. The voltages at the pnl are all good to neutral and P to P.
4. Everything in the pnl has been tightened down.
5. On this 200a service they are on the average only using about 30ish amps per leg.
Double check the amps on each leg once more and make sure everything is super tight. When a current is interrupted, the arc has to be checked. This arc should be contained in a controlled manner. Make sure the gap between the contacts can again withstand the voltage in each circuit.

6. All of the ballasts in all of the cans have been changed out for brand new.
7. The circuit has been moved to a different circuit breaker and from A to B.
Usually according to the customer the whole dimming down to back up to 100% happens over a 2hrish period of them dimming slowly and brightening back up slowly to full brightness. Any ideas to why this is happening
Hopefully the issue gets resolved. Maybe the breakers are tripping intermittently.
 

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Discussion Starter · #13 ·
It could be demand being utilized from the poco. When peak demand hits, small (but noticeable) voltage drop can be seen throughout periods of the day. I had a similar problem with a customers lighting with incandescent fixtures that would dim down.
but the weirdest thing is that other non can florescent 4ft fixtures that are from same PNL do not have this problem it is only the 11ish cans and supposedly some start dimming b4 the others do which is the odd thing.
 

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Discussion Starter · #15 ·
It could be demand being utilized from the poco. When peak demand hits, small (but noticeable) voltage drop can be seen throughout periods of the day. I had a similar problem with a customers lighting with incandescent fixtures that would dim down.
I thought of that and will be installing a power recorder on the pnl and let it log for a day while I am working at another place, but I do know that usually the ballasts if you read the factory specks that they will operate just fine with a +/- 10% of there rated voltage so if its a 120/277 standard ballast then unless in my case 120v drops bellow 108v or above 132v the ballasts should still function properly
 

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Ditch Digging Dummy
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I thought of that and will be installing a power recorder on the pnl and let it log for a day while I am working at another place, but I do know that usually the ballasts if you read the factory specks that they will operate just fine with a +/- 10% of there rated voltage so if its a 120/277 standard ballast then unless in my case 120v drops bellow 108v or above 132v the ballasts should still function properly
Technically they are still operating properly they are just dimmer. Have you looked into what harmonics can do to your circuit with such a small amount of cans. But I've seen weirder things
 
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