Technical Tips
Circuit Breakers and Supplemental Protection Devices
June 2018
Using a 3 pole L8 or L9 device on a 1or 2 pole load
Can you use a 3 pole L9 breaker on a 1 or 2 pole load?
Can you use a 3 pole L8 breaker on a 1 or 2 pole load?
Can I use just 2 of 3 poles from L9-10/3/C (2 phases from 3phase lines) 1st and second pole?
July 2016
L9 Circuit Breaker Auxiliary Contacts vs. Signal Contacts
What is the difference between Auxiliary Contact L9-AMRA3 and a Signal contact block L9-AMRS3?
June 2016
L8 and L9 Trip Curves and Trip Times on DC Applications
Are there trip curves and documentation for trip times when using L8 UL1077 supplemental protectors or L9 circuit breakers in DC applications?
May 2015
Troubleshooting Nuisance Tripping of Molded Case Circuit Breakers
The increased use of high efficieny motors requires a closer look at specifications when applied to circuit protection methods. Not considering all of the factors can lead to specification errors and nuisance tripping or worse.
Technical Guide
November 2014
Methods of Applying Protection Devices
Which protection devices are best for your application? Where do they fit in the schematic of your panel?
Quick Guide
September 2014
Applying UL1077 Circuit Protectors per UL and NEC guidelines
How to design for and apply supplementary protectors in accordance with UL & NEC guidelines.
Technical Guide
June 2014
Short Circuit Current Ratings (SCCR) and Control Circuits
Do the components in a control circuit have a short circuit current rating? UL and NEC rules define which components in a control panel require a short circuit current rating.
September 2013
How does a dual LED blown fuse indicator work?
Indicators on fuse holders and terminals form a parallel path with the fuse they are monitoring. Dual LED indicators may not necessarily utilize both LEDs to indicate a blown fuse.
March 2013
Can components be reused after a short-circuit?
Unlike the fuse box in most residential power centers, industrial circuit protection can rarely be reused after a short-circuit. Some products are specifically tested by UL to withstand a short circuit.
August 2012
How to specify motor circuit breakers
A variety of products can be used to perform as a circuit breaker for motor and non-motor loads, but some perform better than others.