Adjustable breakers

IMO one would think that the Breaker is tested before it leaves the factory so that whatever setting is dialed in when connected in the field it is accurate.
 
jim dungar said:
Yes, but the MEP designer/engineer rarely, if ever, provide the desired settings for all of these functions.
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I tend to agree in the past, but my company tends to do significant projects like public facilities hospitals etc. Every job I have done in recent years has required a coordination study and every breakers settings are provided. The one exception may be the long time setting of a motor load where we are directed to adjust if nuisance tripping occurs.
 
Strathead said:
I tend to agree in the past, but my company tends to do significant projects like public facilities hospitals etc. Every job I have done in recent years has required a coordination study and every breakers settings are provided. The one exception may be the long time setting of a motor load where we are directed to adjust if nuisance tripping occurs.
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That is pretty cool.

Do they put it on the plans or is it in some kind of binder with the TCC curves in it and stuff?
 
On our very large projects the contract usually would call for 3rd party testing. During that testing they would also set all of the adjustable settings which I assumed that they received from the engineers.
 
infinity said:
During that testing they would also set all of the adjustable settings which I assumed that they received from the engineers.
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Way too many horror stories of buildings going dark after they started to get occupied and actually push their power system.

I have had several orders to develop settings (especially ground fault ones) on projects that were fully commissioned per the job specs. Most of the settings were factory presets at minimums, so that is what the commission company tested them at. No one bothered to look at the coordination study, because it was not completed until the EC was already off site and it was needed for the final payment.
 
jim dungar said:
Way too many horror stories of buildings going dark after they started to get occupied and actually push their power system.

I have had several orders to develop settings (especially ground fault ones) on projects that were fully commissioned per the job specs. Most of the settings were factory presets at minimums, so that is what the commission company tested them at. No one bothered to look at the coordination study, because it was not completed until the EC was already off site and it was needed for the final payment.
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You're 100% correct. I was working in a new building under construction where the permanent elevators were transferred over the permanent power. All of the breaker settings in the switchboard were factory set to the minimum. Myself and two other electricians got in the elevator and it moved about 1.5 floors when the adjustable breaker tripped. We were stuck in the dark for 20 minutes. Fortunately one of us had a walkie talkie and we were able to call the foreman who was in another part of the building. He had to reset the breaker and turn the trip settings up to the maximum.
 
Elect117 said:
That is pretty cool.

Do they put it on the plans or is it in some kind of binder with the TCC curves in it and stuff?
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Depends. In healthcare in Florida, the coordination study which is mandatory per NFPA 99 is required to be part of the record drawings, and so it is done by the PE prior to even bidding. Then, if any changes are made, including a different manufacturer, or for example often the generator or HVAC equipment changes, the plans and study must be updated.

In other applications, the specs state that the EC must include a coordination and arc flash study, (the cost here is generally $5,000 to $7500) which we usually include in our estimating BOM and put the onus on whichever supplier and manufacturer they are bidding. The study itself is usually done shortly after submittal approval and if the entire design and construction team is on top of it, large HVAC (and other) equipment is not finalized an ordered until done, because it will also provide AFC at the equipment.
 
Strathead said:
large HVAC (and other) equipment is not finalized an ordered until done,
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In my experience this the exception.
Except for data centers, hospitals and government infrastructure like WWTP, contractors/owners are often willing to take the risk so they can get their projects completed as fast as possible.
 
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