Wylex NB Type 2 MCB'S.......

[jimmy1234]

Hi, Could anybody please tell me the differences between Wylex NB type 1 and type 2 MCB'S, I have just bid and won a type 1 on Ebay and have only just now realised what I really needed was a type 2.

 

[Adam_151]

Tripping curve, 1 is faster than 2

If your circuit meets the requirements for a type 2, then it'll meet the requirements of a type 1 (as Z's is permitted to be higher, etc), however if the load is inductive then there is a higher likely hood of nuisense tripping then with type 2

 

[Pensdown]

Type 1, 2 & 3 (was there a 4?) were predecessors of Type's A, B, C, & D

Type 1 will trip faster that type 3

What is your application for the MCB?

 

[jimmy1234]

Hi, thanks for yor speedy response's....I have bought a 40 amp Mcb to use for an electric shower........have had the consumer unit I intend to use for the shower a few years now but it is only fitted with up to 30 amp type 2 fuses.....the shower will 9.5 kw and the run of 6mm cable will be approx 10 foot from the consumer unit

 

[Adam_151]

No problem with a type 1 on a shower, of course make your your Z's in spec (this will be easier on type 1 than type 2), thought can't imagine there being a poblem with the length you have in mind unless your Ze is out of spec

I would however question your use of a 40A on 6mm² its borderline for that size of cable and it depends on how the cable is routed

and you have notifyed your local building control office of this work haven't you?...

 

[Qedelec]

Type 1, 2 & 3 (was there a 4?) were predecessors of Type's A, B, C, & D

Yes there was a type 4
You will find a type 1 requires a maximum of 1.5 and type 2, 0.86 Ohms of Earth Loop Impedance.

 

[jimmy1234]

Hi, thanks again for speedy responses, the use of the 40 amp is purely so that I can use the consumer unit I already have because as far as I am aware Wylex do not make a 45 or 50 amp for this consumer unit

 

[Pensdown]

What Adams is saying is that the 40amp breaker is there to protect the cable's current carrying capacity, not your shower and it's a bit tight. he's not saying you can't up-rate the cable to 10mm and use the 40amp breaker

 

[jimmy1234]

Thanks for the clarification, I should have explained that apart from having an unused consumer unit I also had leftover 6mm cable and 45amp pull switch

 

[kai]

What Adams is saying is that the 40amp breaker is there to protect the cable's current carrying capacity, not your shower and it's a bit tight. he's not saying you can't up-rate the cable to 10mm and use the 40amp breaker

Surely the MCB Breaker in this case, is there to protect both the cable and the shower unit - as unlike an immersion heater circuit, there is no fuse-connection unit with a cartridge fuse downstream, adjacent the appliance itself.

 

[Pensdown]

It may protect the shower but thats not it's primary purpose. All designs are calculated to protect the system infrastructure not whats connected to it

 

[Jaymack]

Type 1, 2 & 3 (was there a 4?) were predecessors of Type's A, B, C, & D

Type 1 will trip faster that type 3

What is your application for the MCB?

Are the Chinese the makers of type A?

Jaymack

 

[plugwash]

Surely the MCB Breaker in this case, is there to protect both the cable and the shower unit - as unlike an immersion heater circuit, there is no fuse-connection unit with a cartridge fuse downstream, adjacent the appliance itself.

to be honest overcurrent protection is pretty useless for protecting heating aparatus anyway. even 100W is easilly enough to start a fire if its concentrated on a small area of suitablly combustible material and heating equipment usually has powers in the kilowatts.

the real protection for the shower itself mostly comes from a thermal cutout.