Circiut breaker terminology

[thinker]

We received a technical spec from Japan (in English) with reference to circuit breakers types ELB (earth leakage breaker) and NFB (non-fused breaker). Could anybody advise if these types have a corresponding designations in the USA? Or any reference to get educated about these types of breakers?

 

[rbulsara]

ELB are referred to as GFCI circuit breakers. GFCI=Ground Fauult Current Interrupting). This should not be confused with a breaker with a groound fault protection built in a trip unit or a relay.

In the USA all breakers are assumed to be non fused, unless it is specifially stated to be fused. So yes there are fused circuit breakers available. There no accepted abbreviations or acronyms for that that I know of.

There are two types of fused circuit breakers, ones that have Class L fuses only to provide back up short circuit protection and to have a higher short circuit current rating (SCCR or AIC) as a combination of the fuse and the breaker. Other type of fused breaker have current limiting fuses to make the assembly current limiting type and also have higher short circuit rating.

 

[jraef]

The term is actually "No Fuse Breker" and the equivalent in US terminology is a Magnetic only breaker a.k.a. MCP. The term "No Fuse" is probably a mistranslation of "No Thermal Element". You should know however that an MCP cannot be used in the US unless it is part of a listed and tested assembly, so it is doubtful that whatever device you have has been listed that way. You can however just use a regular Thermal-Mag circuit breaker.

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http://www.jraef.com

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[rbulsara]

I should correct one of my statements above:

All breakers are not "assumed" to be non-fused, but they generally are. The key, as your Japanese engineer did, is to specifically state in your specifications if you really do not want fused circuit breakers. Otherwise, a vendor will propose fused circuit breakers (to meet the short circuit ratings if needed). The fused circuit breakers have their own issues, such as cost, physical size and coordination challanges.

Visit website of GE, SQD, Cutler Hammer etc for more info.

 

[thinker]

Thanks a lot to everybody for fast response. It is now a bit more clear about the subject.