- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
I have a single phase transformer with a 120/240 volt, 3-wire secondary. It supplies a MLO Panel less than 10 feet away. There are 10 breaker positions in use on that panel, and provisions for many more. Does this violate 240.21(C)?
Here?s my problem: Look at 240.21(B)(2)(2). There is an explicit requirement that the tap conductors must land on an overcurrent device. Now look at 240.21(B)(1), and while you are at it, check out 240.21(C)(2). Both cases share the 10 foot limit, and neither appears to require an overcurrent device at the load end of the tap conductors. There is a vague (IMHO) allusion to an overcurrent device in 240.21(B)(1)(1)(a), and another in 240.21(C)(2)(1)(a), but I don?t see an explicit requirement that there be an overcurrent device.
I have always required any panel immediately downstream of a transformer to have a main breaker. Now I am uncertain of a code-related basis for that requirement. Any thoughts?
Here?s my problem: Look at 240.21(B)(2)(2). There is an explicit requirement that the tap conductors must land on an overcurrent device. Now look at 240.21(B)(1), and while you are at it, check out 240.21(C)(2). Both cases share the 10 foot limit, and neither appears to require an overcurrent device at the load end of the tap conductors. There is a vague (IMHO) allusion to an overcurrent device in 240.21(B)(1)(1)(a), and another in 240.21(C)(2)(1)(a), but I don?t see an explicit requirement that there be an overcurrent device.
I have always required any panel immediately downstream of a transformer to have a main breaker. Now I am uncertain of a code-related basis for that requirement. Any thoughts?