electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
Reducing breaker setting and conductors
- Thread starter electrofelon
- Start date
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Yes.
There is a lockable/sealable cover over the breaker setting. You meet the NEC as it does not require the settins to be inaccessible.
There is a lockable/sealable cover over the breaker setting. You meet the NEC as it does not require the settins to be inaccessible.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
Thanks jim
mayanees
Senior Member
- Location
- Westminster, MD
- Occupation
- Electrical Engineer and Master Electrician
Those are factory-default settings. If you're trying to coordinate with anything, let me know what the device is, and I'll send you the settings. I have access to a network package of SKM.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
Awsome thanks. Its probably not very critical in this case, its the breaker on a 400 KW generator (120/208). It will be feeding a 2000A transfer switch then a 2000A switchboard horizontal bus with 2 sections.
- Location
- Illinois
- Occupation
- retired electrician
The rules for this are in 240.6(B) & (C). Most breakers fall under (C).
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
Typically do these dials have indents at the numbers indicated and I Can only use them, or is it continuous and I can set it between two numbers?
Deltaforce
Senior Member
- Location
- India
- Occupation
- Electrical Engineer
Not calibrated between points
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Most of them, over the past 30 years, have pointers and detents.
Setting between detents will often confuse the breaker and probably cause it assume its lowest possible settings.
If they were infinitely settable you would need to injection test the breaker to make sure it was doing what you think it should do.
Electronic relays, like an SEL, are set using software any can accept any value of pickup point.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
Ok Ill just design around those available settings
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
one more question: Any advice on what I should set the other dials to? Long time will be set at about .5, maybe .6. This is the output breaker on a generator, 120/208, 400Kw. Feeding a switch board. I dont know off hand what the largest downstream OCPD is.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
I made good money choosing appropriate protection settings.
But, one thing you can do is to set your adjustable breaker to match the curve of an equivalent standard non-adjustable breaker. The short time, instantaneous, and ground fault adjustments will be based on the full rating of the breaker sensor, not what you set the long time to. There is nothing wrong with leaving them at the factory defaults, which are usually the minimums.
I tried to coordinate my GF settings with the smallest branch breaker I could. I did not want someone working on a live small branch circuit taking down my main breaker, but I didn't want to set them at the maximum either. For main breakers I liked trying to coordinate with a 30A. I also found setting the time delay was much more important than the pick up point. I don't think I was ever able to coordinate with any branch larger than 70A regardless of the settings, which is why I like 2 levels of GF.
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Those are switches, not variable resistors.
Many of the newer Square D breakers can also be programmed via a menu, and by pressing buttons on the front of the breaker. But that takes a lot more time, and it's harder to tell how its set. But that sometimes gives you access to settings that are more exact.