breaking capacity of overcurrent devices

[Adam_92]

I’m wondering if someone can tell me in the OSG or regs that it has the short circuit breaking capacity of overcurrent devices someone said it was table 7.2A but can’t find it anywhere

 

[buzzlightyear]

what size breaker is in now ? .page 74 in byb, having blue in the van ,cant be a**t to get it.

 

[plugsandsparks]

didn't know there was a table, thought you just measure PSCC and make sure that the breaker capacity is greater.

 

[Richard Burns]

Try table 7.2.7(i) on page 79 osg. 18th blue edition.

 

[buzzlightyear]

didn't know there was a table, thought you just measure PSCC and make sure that the breaker capacity is greater

hit me down with a sock ,you live and learn .

 

[Strima]

7.2.7(i) OSG page 79.

 

[buzzlightyear]

Try table 7.2.7(i) on page 79 osg

7.2.7(i) OSG page 79

thats not fair, I'm now going to hide up in attic now .

 

[telectrix]

thats not fair, I'm now going to hide up in attic now .

don't chew the cables.

 

[Adam_92]

Thanks very much guys also quick question where do I find codes for types of wiring? I have found the codes for installation methods

Another pick of the brains I know earth bonding should be less than 0.05 ohms but where in the regs/osg does it state that?

 

[telectrix]

Thanks very much guys also quick question where do I find codes for types of wiring? I have found the codes for installation methods

Another pick of the brains I know earth bonding should be less than 0.05 ohms but where in the regs/osg does it state that?

types of wiring usually bottom of schedule of test forms. and earth bonding is not 0.05 ohms. that's a myth. the 0.05ohms refers to the resistance between a bonding conductor and the pipe its bonded to ( i.e. across the bonding clamp)

 

[davesparks]

I’m wondering if someone can tell me in the OSG or regs that it has the short circuit breaking capacity of overcurrent devices someone said it was table 7.2A but can’t find it anywhere

The short circuit capacity of circuit breakers will be printed on the circuit breaker and will usually be either 6kA or 10kA for mcbs but can be other values, mccbs and accbs will have higher ratings.
For fuses or other devices you'll have to look up manufacturers information.

 

[telectrix]

just to hi-jack thread, did a EICR yesterday . proteus 3871 MCBs, am i right in thinking 3kA?

 

[plugsandsparks]

Now i have been forced to look in a book, there appears to be a range of values for 3871 mcbs, M1-9 equals 1-9KA. TBH the table is a bit useless in my job, i always end up looking at breaker or selecting a breaking based on MI.....

 

[Lucien Nunes]

proteus 3871 MCBs, am i right in thinking 3kA?

The plug-in type were M3, but the normal DIN-rail type 2's I think were M6. The only breaking capacity I'd really trust them with would be to break in half, which seemed to be an unavoidable consequence of trying to install them.