b type or c type

[Farmelectrics]

been doing some domestic testing for a freind of mine who has his own firm now i allways use to use b type breakers in domestic dwellings but ive noticed quite alot of c type recently on theses tests your thoughts

 

[kingeri]

Had to use occasionally on lighting circuits due to inrush current.

 

[Darkwood]

As long as it meets Zs requirements then not an issue, type 'd' would be just as good as long as Zs is met.

 

[MarkieSparkie]

The usual reason for choosing to use Type C MCB in preference to a Type B would be in situations where switching surges would be likely to operate a Type B MCB. Typical situations occur frequently in commercial and industrial installations where there is a wide spread use of discharge lighting, small motors and pumps. For example the highly inductive nature of fluorescent lighting banks are a particularly common source of switching surges requiring a less sensitive MCB. In domestic situations they are required occasionally for home workshop machine tool motors, welder supplies, and shower pumps etc.
Type B MCBs typically operate in the conventional time (0.1 to 5s) at a trip current between 3 and 5 times the nominal current rating (In) of the device. Whereas Type C MCBs are less sensitive and typically operate at a trip current between 5 to 10 In.

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[i=p/u]

what can i say, you guys know as much as me..

 

[Amp David]

Used Type C's on a rewire sometime ago. Loads of halogens installed, so instead of going for the standard of type B MCBs then it tripping everytime a lamp blows, thought i'd fit type C MCBs.

I designed the circuit so knew that my Zs would easily comply with that of a type C.

 

[Darkwood]

Used Type C's on a rewire sometime ago. Loads of halogens installed, so instead of going for the standard of type B MCBs then it tripping everytime a lamp blows, thought i'd fit type C MCBs.

I designed the circuit so knew that my Zs would easily comply with that of a type C.

If your lamps were selv then the inrush on the transformers would be given extra allowance with a type c, if they are standard 240v GLS or GU10's well any filament lamp then your thinking it reduces tripping when lamps blow is incorrect, as the filament collaspes it leaves an ionized path which has zero resistance and creates a short circuit long enough to trip the mcb irrespective of B,C or D types the time curve is instant on a short with high ampage.

 

[Guest55]

what can i say, you guys know as much as me..

no need for insults lol.
;-)

 

[Amp David]

If your lamps were selv then the inrush on the transformers would be given extra allowance with a type c, if they are standard 240v GLS or GU10's well any filament lamp then your thinking it reduces tripping when lamps blow is incorrect, as the filament collaspes it leaves an ionized path which has zero resistance and creates a short circuit long enough to trip the mcb irrespective of B,C or D types the time curve is instant on a short with high ampage.

Oh right, how come the breakers held then. 3 have popped since installation.

 

[Darkwood]

They dont always blow that way, its random but if the breaker does trip it would have tripped a 'b,c or d'.... it might sound strange but just ask yourself why a mcb would trip just cos the filament broke as its not inductive when it breaks it open circuits and the gas is inert.

 

[telectrix]

Oh right, how come the breakers held then. 3 have popped since installation.
you've just been lucky. or could be , however, that the C or D types might withstand the fault current as it's of extremely short duration. nobody can tell the magnitude of said fault current when a lamp blows. it could just be within the capability of the C or D.

 

[i=p/u]

in short its a short when lamp blows...

 

[ipf]

in short its a short when lamp blows...

Depends if it shorts or not.

 

[telectrix]

bit cool for shorts tonight.

 

[i=p/u]

halogen lamps trip breaker/fuse if lamp fails... in my expierience..... 9 times out of ten, sure doo..

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not for this sweaty betty