exam question help (student stuck)

[josh494949]

hey there im a student training to become a electrician on a city and guild 2330 course

i have a simple question but just want to make sure

my question is as follows

------------------------------------------------------------
circuit / circuit breaker / rated short circuit current
lighting / 6A / ?
power / 32A / ?
------------------------------------------------------------

i think its 6000A for both but that does not seem right (i made some poor notes now not sure if this is correct)

the question refers to domestic single phase its a simple question so no need to over think it?

can any one help???

 

[ian.settle1]

hey there im a student training to become a electrician on a city and guild 2330 course

i have a simple question but just want to make sure

my question is as follows

------------------------------------------------------------
circuit / circuit breaker / rated short circuit current
lighting / 6A / ?
power / 32A / ?
------------------------------------------------------------

i think its 6000A for both but that does not seem right (i made some poor notes now not sure if this is correct)

the question refers to domestic single phase its a simple question so no need to over think it?

can any one help???

It depends upon what the PFC is when you do the design calculations. It could also be 10Ka

 

[Guest123]

For most domestic type B MCB's it will be 6000A or 6KA.

You'll find it on the front of the MCB in a box - 6000. Some may be rated at 10KA though so watch for that. Again it will be on the front of the MCB in a box - 10000.

 

[baldsparkies]

A lot of modern mcb's have a pfc rating of 6k (6,000 amps) so your notes are probably correct especialy if its a b type BS EN 60898 b types being the most populer in domestic installs

 

[josh494949]

thanx so much i had this wrote down but when you question your self you just cant stop lol
so this would be 6000a at 240v for a 6a and a 32a mcb?

thanx so much guys

 

[baldsparkies]

Josh, just relate to exactly what the 6000A means ie The mcb is a mechanical device and the manufacturer is saying it can withstand a maximum current under fault conditions of 6000 amps. That would however be a one off disconnection cus thats a pretty high fault current.In the real world it is very unlikely that an mcb would have to undergo that kind of punishment due to other governing factors,but thats another story.