birddogger
Electrical
- Feb 23, 2004
- 31
I am trying to determine if a Square D type NEHB panelboard with type EHB branch circuit breakers (both discontinued) can be used in series with a type KI breaker, on a system with approx. 35kA available fault current.
The EHB breakers are rated for 14kA at 277/480, but literature from our Square D binder indicates that when they are applied to the load side on an I-LIMITER breaker, they are UL listed for use on systems with up to 100kA avail. fault current.
The KI breaker is a current-limiting device, and carries the I-LIMITER name. However, since the KI series of breakers came out well after the NEHB literature stating the series-rating conditions, I'm hesistant to assume that KI and NEHB are automatically compatible under this fault current condition.
Unfortunately, all of Square D's series-connected compatibility charts only cover their current lines of breakers and panelboards. So there are no cross-referencing information on EHB breakers (or NEHB boards) with type KI breakers.
If we get our I-Line panel with a factory-installed KI breaker, the added cost of the breaker will easily offset the labor & materials required to replace the downstream NEHB panel with a modern NF panel (in which case we would only need a type KC breaker in the I-Line), and to re-terminate all of the existing branch circuits on the new panel.
If the existing NEHB panel was quite old, I would replace it without hesitation. But it's a 1996 vintage, a little too new to demo if I can justify otherwise.
The EHB breakers are rated for 14kA at 277/480, but literature from our Square D binder indicates that when they are applied to the load side on an I-LIMITER breaker, they are UL listed for use on systems with up to 100kA avail. fault current.
The KI breaker is a current-limiting device, and carries the I-LIMITER name. However, since the KI series of breakers came out well after the NEHB literature stating the series-rating conditions, I'm hesistant to assume that KI and NEHB are automatically compatible under this fault current condition.
Unfortunately, all of Square D's series-connected compatibility charts only cover their current lines of breakers and panelboards. So there are no cross-referencing information on EHB breakers (or NEHB boards) with type KI breakers.
If we get our I-Line panel with a factory-installed KI breaker, the added cost of the breaker will easily offset the labor & materials required to replace the downstream NEHB panel with a modern NF panel (in which case we would only need a type KC breaker in the I-Line), and to re-terminate all of the existing branch circuits on the new panel.
If the existing NEHB panel was quite old, I would replace it without hesitation. But it's a 1996 vintage, a little too new to demo if I can justify otherwise.
