Series rated NEC 240.86

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highpowered

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los angeles
I am confused about this section of the code. How do I "prove" That my downstream circuit breakers that are part of the series combination remain passive during the interruption period of the line side fully rated current limiting device? Is this done through fault current calculations? I've never been asked to prove this before. I am assuming I must submit my details from siemens on the breakers I'm installing. Plus submit Fault current calculations. They are also requiring I make placards stating the Catalog numbers of all breakers. My system is as follows:
Utility stated AIC= 42,000
Single phase system 400A 120/240V EMT 2" 4/0 Parallel conductors (3) per pipe 28' length. terminates to 400A 85KAIC Siemens 3VA53 Molded case breaker.
Downstream to power mod 16 units + 1 house panel. 60A 65 KAIC 2 pole breakers at meters. Siemens Q260HH
To the units shortest distance is 40' longest 175'. Main lug panels the breakers there are 10,000AIC. EMT flex combination.

Thanks in advance
Jason
 
I have never heard of any professional engineer taking responsibility for making 'series ratings' in the field.

In 99.9999% of installations the series ratings are taken from breaker manufacturer's literature which is based on actual "witnessed" testing.

This requirement has been in the NEC for many decades. You can get more information from breaker manufacturers.
 
jim dungar said:
I have never heard of any professional engineer taking responsibility for making 'series ratings' in the field.
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The only opportunity to "make a series rating" is from 240.86(A), which is for existing installations only and I do not know any modern day PEs that would take on that risk.

highpowered said:
I am confused about this section of the code. How do I "prove" That my downstream circuit breakers that are part of the series combination remain passive during the interruption period of the line side fully rated current limiting device?
Click to expand...

If there is a circuit breaker or fuse that tries to open the circuit during a fault, they are not passive. A passive component would be something like conductors or busway that attempt to withstand the current and remain passive, although I would claim that conductors and busway and other passive equipment, do in fact change their impedance characteristics during a fault as they heat up and potentially damage and I wouldn't consider passive
 
highpowered said:
I am confused about this section of the code. How do I "prove" That my downstream circuit breakers that are part of the series combination remain passive during the interruption period of the line side fully rated current limiting device? Is this done through fault current calculations? I've never been asked to prove this before. I am assuming I must submit my details from siemens on the breakers I'm installing. Plus submit Fault current calculations. They are also requiring I make placards stating the Catalog numbers of all breakers. My system is as follows:
Utility stated AIC= 42,000
Single phase system 400A 120/240V EMT 2" 4/0 Parallel conductors (3) per pipe 28' length. terminates to 400A 85KAIC Siemens 3VA53 Molded case breaker.
Downstream to power mod 16 units + 1 house panel. 60A 65 KAIC 2 pole breakers at meters. Siemens Q260HH
To the units shortest distance is 40' longest 175'. Main lug panels the breakers there are 10,000AIC. EMT flex combination.

Thanks in advance
Jason
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Maybe stupid questions, but have you confirmed there is more than 10 k at the 10K branch breakers? And have you checked that what you have does not meet a tested combination?
 
electrofelon said:
Just as a little aside, what is the point of this? I mean if it's existing, who is caring about or requiring an approved series rating?
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I always performed device evaluations as part of my studies in existing facilities, especially as part of NFPA 70E compliance.
 
electrofelon said:
Just as a little aside, what is the point of this? I mean if it's existing, who is caring about or requiring an approved series rating?
Click to expand...
You would be surprised how many utilities change the available fault current over decades, as the grid changes. Many of my clients get primary medium voltage service, and the fault current of 20-30 years ago was smaller than now.
 
To be clear I am replacing the existing 200Amp service for 16 unit apartments to a 400 Amp. The units are 10kaic. Closest unit is 40 feet. furthest is 185ft. 60amp. single phase 120/240. Metalic Raceway. My corrections from the Authority having Jurisdiction are to summarize
1) Provide supporting Documentation Systems employing series rating...
A, Manufacturers Catalog sheets verifying an approved series rated system. ( I cant find anything saying it is Series Rated) The main breaker is Siemens 3VA53 400A MJAS 85KAIC)
B. Comply section 110.22 and 240.86A This is Labeling?

electrofelon said:
Maybe stupid questions, but have you confirmed there is more than 10 k at the 10K branch breakers? And have you checked that what you have does not meet a tested combination?
Click to expand...
 
Have you calculated the available fault current at each unit? This is step one.
You know the new main breaker, what are the unit breakers?
Is this a multi-meter center? It looks like you may need a rating for 3 breakers in series assuming there is a breaker feeding each unit. What is the feeder breaker.
 
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jim dungar said:
I have never heard of any professional engineer taking responsibility for making 'series ratings' in the field.

In 99.9999% of installations the series ratings are taken from breaker manufacturer's literature which is based on actual "witnessed" testing.

This requirement has been in the NEC for many decades. You can get more information from breaker manufacturers.
Click to expand...
In Siemens Catalog it does not specifically say what they are asking. Siemens hasn't responded in weeks. I will keep trying
 
jim dungar said:
Have you calculated the available fault current at each unit? This is step one.
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Yes I used the Excel sheet from this site !! my 40 ft unit is the highest at 6,600. My house panel which is the closest to the service is 8,200. I dont understand if my Main breakers for these panels are rated 65KAIC would that not trip first? Protecting anything downstream? I get doing Fault Calculations for anything close to the utility transformer but the further you travel from the source the fault is always well below 10k?
 
electrofelon said:
Just as a little aside, what is the point of this? I mean if it's existing, who is caring about or requiring an approved series rating?
Click to expand...
Because I am replacing the service. I assume since Multimeter panels are hard to get they want correct documentation for them. I have waited 3 years for this panel I almost went to Mexico myself to get them!
 
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