I saw a tandem 14 sq-d in a bolt on panel in a resturant the other day. I was a bit suprised. I have never seen tandems in a bolt on before. Is this common? Or did somebody jury rig here. I didn't remove the panel cover, as I was there to look at something else.
#64059 - 03/30/0612:58 AMRe: Need more room in Panel...
Square D Panelboards accept both QOB (bolt on) and QO (plug on) breakers. I have been told that they recommend using QO breakers instead of QOB when adding additional breakers in the field. I can pretty much guarantee that the panelboard was not listed for tandem breakers and I’m sure the breaker used was clearly marked non-CTL for replacement use only.
BigB, what new Homline tandem breakers are you referring to? HOMT breakers in 15 and 20 amp have been available since the beginning of Homeline. They later added the larger quad breakers (30-50).
#64060 - 03/30/0612:06 PMRe: Need more room in Panel...
The old Square D tandem breakers were front-to-back. The tandems since the 80's have been side-by-side. The new design gives the 2 pole devices the appearance of a quad breaker, but it is really (1) 2pole + (2) 1poles.
All UL Listed panels built since the 60's are CTL. So non-CTL breakers should only be installed in panels that are over 40 years old that have wiring diagrams showing which spaces are designed for tandem circuits.
My personal belief is that non-CTL tandem breakers should go the way of the old delta breakers.