sevis
Member
- Location
- Baton Rouge, LA
Hi all,
The situation is that we have a hotel renovation which involves replacing fan coil units for all guest rooms. These units are hydronic cooling units with electric heat strips.
The question I have is 2 parts. For the units we are installing, the largest units have a 22A MCA and 25A MOCP. I have read many articles and seen videos by Mike Holt and others on the MCA/MOCP debate and we now abide by these numbers for HVAC equipment installations, so we are frequently installing wiring with smaller ampacities than the breakers. My first question is about article 240.4(D)(5) which states that #12 wire can't be protected by an overcurrent device larger than 20A unless there is an exception in 240.4(G).
240.4(G) contains an exception for Air Conditioning and refrigeration equipment circuits (440, Parts III and IV). I'm wondering why there isn't also an exception for heating equipment like I described above. Or am I thinking about this completely wrong? Is there another section of code that states that we can use the manufacturer provided MCA/MOCP on equipment regardless of the small conductor rules and exceptions?
The second question is that after diving into this hotel, we realized that several existing fan coil units are circuited together, sometimes up to 3 on a circuit. Considering that most of the existing units have an MOCP of 15, is it possible for them to be on 20A or 25A circuits without there being some kind of code violation or manufacturer warranty violation? As far as I can tell, there is no local overcurrent device like an enclosed circuit breaker adjacent to the units to help satisfy the manufacturer 15A MOCP requirement, so I'm wondering how these installations passed inspection.
Thank you for any help and I am happy to provide more information.
The situation is that we have a hotel renovation which involves replacing fan coil units for all guest rooms. These units are hydronic cooling units with electric heat strips.
The question I have is 2 parts. For the units we are installing, the largest units have a 22A MCA and 25A MOCP. I have read many articles and seen videos by Mike Holt and others on the MCA/MOCP debate and we now abide by these numbers for HVAC equipment installations, so we are frequently installing wiring with smaller ampacities than the breakers. My first question is about article 240.4(D)(5) which states that #12 wire can't be protected by an overcurrent device larger than 20A unless there is an exception in 240.4(G).
240.4(G) contains an exception for Air Conditioning and refrigeration equipment circuits (440, Parts III and IV). I'm wondering why there isn't also an exception for heating equipment like I described above. Or am I thinking about this completely wrong? Is there another section of code that states that we can use the manufacturer provided MCA/MOCP on equipment regardless of the small conductor rules and exceptions?
The second question is that after diving into this hotel, we realized that several existing fan coil units are circuited together, sometimes up to 3 on a circuit. Considering that most of the existing units have an MOCP of 15, is it possible for them to be on 20A or 25A circuits without there being some kind of code violation or manufacturer warranty violation? As far as I can tell, there is no local overcurrent device like an enclosed circuit breaker adjacent to the units to help satisfy the manufacturer 15A MOCP requirement, so I'm wondering how these installations passed inspection.
Thank you for any help and I am happy to provide more information.
