type c and b

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Lee321

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when do you use type b or c for sockets or lighting?

 

DonkeyDong

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hi there,

Its normally when the circuit has a higher inrush current than a type b can handle with out tripping. Have a look in the big red book at the back. It shows the tripping characteristics (i haven't got the regs in front of me)

D.

 

Lee321

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yeah i know that type c has a greater ability to hold in when a surge occurs

but what determins typically when you would install c over b?

 

Admin1

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On a call out where you haven't enough time to look into a fault that keeps tripping a Type B BS60898 therefore, putting in a Typre C BS60898, as a temporary safety measure?

 

The Godfather

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yeah i know that type c has a great ability to hold in when a surge occursbut what determins typically when you would install c over b?
Large banks of Flourescant lighting.

Certain types of Workshop machinery for example.

Don

 

Lee321

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Don. I'm interested. What sort of workshop machinary? Is it items which require a very large starting current such as table saws/spindle moulders?
anything motor wise or fluoresent lighting has high start currents so the type b might not hold,

its all to do with inductive or resistive loads :)

 

The Godfather

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Don. I'm interested. What sort of workshop machinary? Is it items which require a very large starting current such as table saws/spindle moulders?
This would depend on the actual start up current, specified by the manufacturers of the machinery.

I have seen an instance of a 16A type B mcb, unable to supply (without tripping) a 1.8KW circular saw, for example.

Don

 

The Godfather

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anything motor wise or fluoresent lighting has high start currents so the type b might not hold,its all to do with inductive or resistive loads :)
Inductive yes, resistive no.

Don

 
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This would depend on the actual start up current, specified by the manufacturers of the machinery.I have seen an instance of a 16A type B mcb, unable to supply (without tripping) a 1.8KW circular saw, for example.

Don
my basic understanding 1800/240 = 7.5amps!

Must have a hell of a draw @ start up

I sent a mitre saw back as faulty as it kept tripping my MCB on a 13A supply

:|

 
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This would depend on the actual start up current, specified by the manufacturers of the machinery.I have seen an instance of a 16A type B mcb, unable to supply (without tripping) a 1.8KW circular saw, for example.

Don
Is that when you are removing those horses heads for the boys to dispatch? :|

 

Lee321

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my basic understanding 1800/240 = 7.5amps!Must have a hell of a draw @ start up

I sent a mitre saw back as faulty as it kept tripping my MCB on a 13A supply

:|
1 to be remembered ! especially if it comes back not faulty !

 

The Godfather

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Is that when you are removing those horses heads for the boys to dispatch? :|
I believe my boys, use whatever is available to hand, but the Don

never discussses such minor details.

The Godfather

 

steptoe

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yeah i know that type c has a great ability to hold in when a surge occursbut what determins typically when you would install c over b?
as a general rule C is motor rated, inductive load

and D is transformer rated, resistive load.

B is just a general use run of the mill middle of the road.

remember tho, if you go from a B to C you will half your permitted Zs, and from a C to D you will half it again.

Zs B = 46/MCBrating

Zs C = 23/MCBrating

Zs D = 11.5/MCBrating

I think. Pray

 

extension15

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as a general rule C is motor rated, inductive loadand D is transformer rated, resistive load.

B is just a general use run of the mill middle of the road.

remember tho, if you go from a B to C you will half your permitted Zs, and from a C to D you will half it again.

Zs B = 46/MCBrating

Zs C = 23/MCBrating

Zs D = 11.5/MCBrating

I think. Pray
Indeed so, consideration for the cable size, also comes into effect when using type C or D MCBs...

:D

 
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as a general rule C is motor rated, inductive loadand D is transformer rated, resistive load.

B is just a general use run of the mill middle of the road.

remember tho, if you go from a B to C you will half your permitted Zs, and from a C to D you will half it again.

Zs B = 46/MCBrating

Zs C = 23/MCBrating

Zs D = 11.5/MCBrating

I think. Pray
Once again Mr Steps.. another Important Gem' added to the topic! ; )Applaud Smiley

 

Lee321

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its a simplistic way of describing it, and how exactly would you describe the load from a transformer then?
it is inductive.

a filament light bulb or load that has no coil is resistive only

 

steptoe

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it is inductive.a filament light bulb or load that has no coil is resistive only
so we measure across a transformer with an AC voltage (NOT DC ala your meter!) why do we get a resistance? and that is why we need to use a different characteristic MCB to avoid tripping on this load?

ALL electrical loads are resistive to a degree or less, its the nature of the fundamentals of electricity, you still semm to have difficulty grasping the basics.

NOT everything can be found in a book or on google.

 

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