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Sizing a service 230.90(A) Exception 3 and FBC Residential E3603.3.1 Exception.

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This weeks post comes from a couple of questions asked these past couple weeks about sizing a service.  I was asked why you have to add the breakers up to get the size of the main!  I told them to look at section 230.90(A) Ex.. #3in the NEC and in the Florida Building Code Residential E3603.3.1 exception.  This is not a new so I don’t understand how someone could come to the conclusion that the main “MUST” be based on adding up all the breakers in the panel or all the mains at a service.  The exception to this section allows us to size the main based on a calculation, and not by adding the breakers together, because if that was the correct way to size the main I would need 600 amps for the main in my home and my 2/0 wire would be way to small.  In the slides below there is a 400 ampere service with four 200 ampere mains, which to the layman would look like an 800 ampere service but in reality it is only a 400 ampere service, because the calculated load was only 340 amperes and we used 500 Kcmil Cu. wire which has an ampacity of 380 amperes at 75c which is good for a 400 amp service see 240.4(B).

 

230.90c

230.90b  

Hope this helps.

 

Jake

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Florida Statute 553.883 SMOKE ALARMS

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This will be the third time that we visit 553.883 the new statute that allows us to install battery operated smoke alarms.  As in my past requests I am still trying to find an alarm that is battery operated (sealed 10year type) that can be interconnected.  I have been trying to find one but can only find them in Europe. Has anyone come across ones we can buy here in the USA?

We have 10 year battery operated ones but they do not interconnect, or they interconnect but don’t have ten year battery.  I have been to inspector meetings and have taught classes that have had someone tell me they installed one or seen them used in an installation.  Please email a type that I can buy here in the good old USA.  At these meeting I have been told that the Statute requires interconnection (they say it is implied) but again I have not been able to find one that meets the requirements of the Statute and interconnects.  All of the specs sent to me are not sealed battery 10 year type.  Only one of all the smoke alarms that has been sent to me had 10 year battery and was inter-connectable and that was BRK SA410LLi but I can not find it anywhere here in the states to buy, it was only available in the UK.  Please read the Florida Statue 553.883 below.  So help me find what inspectors and other officials are saying is a requirement, and I will pass it on.  So we can all be on the same page.

553.883 REQUIRES a SMOKE ALARM to have:

10 YEAR NONPLACEABLE BATTERY

NONREMOVABLE BATTERY

“INTERCONNECTABLE” SMOKE ALARM   (I don’t believe that this was the intent)

 

 553.883 a

 

Till next week work safe be safe

 

Jake

Continue ReadingFlorida Statute 553.883 SMOKE ALARMS