I an trying to determine the maximum Zs for the spare 16 amp MCB with a 5 second disconnect time.
The maximum Zs of the SWA distribution circuit will be less than 1.4 ohms using a third core as the CPC not including the armour, so it will be lower.
Edit- taking Ze as 0.8 ohms TNS.
professional-electrician.com/.../
If not you could go at it the other way - it will be a type 1 or 2 in domestic, so a lot better than a C type, and comparable to a B type.
Taking the 1,4 ohms figure, I get PSSC to earth of 230/1.4 or 160 Amps - ten times the breaker rating of 16A. You are in luck , and in the 'instant trip' part of the curve for a type 3 as well. ;-) Or you could worry about Cmin, and hot cables, and only be really sure about types 1,2,
The older (10,15 30 series not 10 16 32) of type 1s. As hosted on TLC website.
And same idea for type 3 where 160 amps is right on the line between instant and thermal. I'd expect that maybe in a more industrial setting.
Mike.
If not you could go at it the other way - it will be a type 1 or 2 in domestic, so a lot better than a C type, and comparable to a B type.
Taking the 1,4 ohms figure, I get PSSC to earth of 230/1.4 or 160 Amps - ten times the breaker rating of 16A. You are in luck , and in the 'instant trip' part of the curve for a type 3 as well. ;-) Or you could worry about Cmin, and hot cables, and only be really sure about types 1,2,
The older (10,15 30 series not 10 16 32) of type 1s. As hosted on TLC website.
And same idea for type 3 where 160 amps is right on the line between instant and thermal. I'd expect that maybe in a more industrial setting.
Mike.
