1000 Amp Non-adjustable trip Breaker

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raider1

raider1

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Are there any 1000 ampere or above, Non-adjustable trip circuit breakers with the ability to disable the instantaneous trip portion commercial available?

This question is in regards to 240.87 (2011 NEC)

Chris
 
I believe the UL 489 standard for 'thermal-magnetic' molded case breaker requires that they have some type of inherent 'instantaneous' protection, or else they could not be used with switchboards and panels that only have 3-cylce fault ratings.
 
zog said:
Sure, molded case or power breaker?
Click to expand...

Either one. What I am trying to ascertain is whether there are 1000 ampere or higher breakers available that are non-adjustable type but could have the instantaneous trip function disabled for selectivity.

As currently stated 240.87 applies to all circuit breakers without an instantaneous trip.

Chris
 
jim dungar said:
I believe the UL 489 standard for 'thermal-magnetic' molded case breaker requires that they have some type of inherent 'instantaneous' protection, or else they could not be used with switchboards and panels that only have 3-cylce fault ratings.
Click to expand...

What about power circuit breakers or insulated case circuit breakers?

Chris
 
jim dungar said:
I believe the UL 489 standard for 'thermal-magnetic' molded case breaker requires that they have some type of inherent 'instantaneous' protection, or else they could not be used with switchboards and panels that only have 3-cylce fault ratings.
Click to expand...

The MCCB's that I am familiar with that have an "INST off" feature still have a trip with no delay that occurs at the ST withstand rating. So that meets the UL requirement, and seems to still apply to 240.87. (?) I think.
 
zog said:
The MCCB's that I am familiar with that have an "INST off" feature still have a trip with no delay that occurs at the ST withstand rating. So that meets the UL requirement, and seems to still apply to 240.87. (?) I think.
Click to expand...

Yes it does.

If the device is listed to UL489, regardless of its construction, it will always have some Instantaneous protection, even if the device setting is "OFF".
This inherent protection often plays havoc with selective coordination requirements in the "700" articles of the NEC.

Power breakers (e.g. built to ANSI C37 or UL 1066) have actual Short Time withstand ratings and therefore do not need inherent Instantaneous protection.
 
So would it be safe to say that I could purchase a non-adjustable trip power circuit breaker without instantaneous trip?

Chris
 
zog said:
Never heard of a non adjustable trip power CB
Click to expand...

That is what I am trying to ascertain whether or not there are any non-adjustable trip breakers (Power, MCCB, or other type) available that do not contain an instantaneous trip function or a instantaneous trip function that can be overridden for selectivity.

Chris
 
raider1 said:
That is what I am trying to ascertain whether or not there are any non-adjustable trip breakers (Power, MCCB, or other type) available that do not contain an instantaneous trip function or a instantaneous trip function that can be overridden for selectivity.

Chris
Click to expand...

Not sure what you mean by non adjustable trip breakers? That is like a residential breaker. I thought Jim and I answered the question clearly, now you are confusing me.
 
Sorry for the confusion.:)

Yes you both answered my question. I got confused myself.:)

I went back and re-read the section that I am researching and found that I read the section wrong.:ashamed::ashamed::ashamed:

Thank you for the input gentleman I really appreciate it.

I had read "adjustable trip breaker" instead of "adjustable instantaneous trip function".

Chris
 
Man I feel like an idiot.:ashamed::D

How did I read that so wrong.:slaphead:

You every have one of those days.............

Chris
 
I was researcing information in regards to a comment made to CMP 10 in regards to 240.87

I had read the wording in the comment as "Adjustable trip circuit breaker" where the comment actually read "Circuit breaker where the adjustable instantaneous trip is disengaged".

Thanks again for the help.

Chris
 
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