HorneTD wrote:

Turtle
Unless the panel is designed for tandem breakers installing them
violates the listing of the panel which violates the US National
Electric Code. If that violation were to cause a fire the insurance
carrier could walk away from the loss and decline to pay it.
Breakers
marked for replacement use only are recognized or listed for use in
panels that were designed for tandem breakers but were manufactured
before the requirement for circuit limiting (CTL) assemblies was
adopted. CTL assemblies will only accept the number of tandem or
half
width breakers for which they were designed. Pre CTL assemblies rely
on
the installer to obey the requirement of NFPA 70, section 110.3
Examination, Identification, Installation, and Use of Equipment which

reads in part B "B) Installation and Use. Listed or labeled equipment

shall be installed and used in accordance with any instructions
included
in the listing or labeling." That includes the list of breakers that

are include on the interior labeling. Just because a non CTL breaker

will physically fit in the panel does not make it OK to use in that
panel.
--
Tom H

OK......well and good for someone knowing the code and all. But, in
regular do-it-yourself language....how can I tell if a breaker box is
OK with a tandem breaker?