BS3871 Max Zs values

[sellers]

does anyone know where these are in the regs? or where can I find them?

 

[meerkat]

Hi Sellers,

try O.S.G page 103, table 2D,

what size and type of breaker you looking at?

(MEERKAT)

 

[Manator]

A good tip when you can not find any tables, or when you are onsite without your reference materials is to calculate the max Zs.

BS 3871 are from around 1965, they are split into type 1, type 2 and type 3. Type 1 allows 4 times the breakers rating type 2 is 7 and type 3 is 10.

So if we take a 15amp type 1 as an example we have 15x4 giving us 60, 230/60 = 3.83 max Zs.

 

[meerkat]

Hi Manator,

would the 3.83 max Zs reading then be multiplied by 0.8 to account for the thermal increase under fault conditions, cheers (MEERKAT)

 

[Manator]

If you wanted to calculate for temp to get the rule of thumb 80% value then yes.

 

[Litttle Shonet]

Have a look in the download section under Electrical Downloads - certificates.

I've just downloaded it. Looks quite good

 

[Barx]

If only there was an app for this sort of thing....

 

[Manator]

Looks like a good app to include barx and could be very useful for any PIR's