Type of Breaker

[jimmyray]

Hi all. I installed a ring main the other day, and the breaker was a Type C 32A. I was wondering why the breaker was Type C and not B, as the circuit was feeding twin socket outlets in dado trunking, with only PCs and office stuff connected. This tends to be the case for all circuits where I work. I thought a Type C was for loads with a higher inrush current on startup. Any help appreciated. Cheers. Jim

 

[Simonslimline]

Have you asked at work? what was your highest Zs reading for the ring final?

 

[jimmyray]

Hi Simon, max Zs was 0.51 Ohms. I haven't really been given a straight answer at work, so I thought I'd ask in here to see the typical scenarios where you would use Type C over a Type B for a ring main. Cheers. Jim

 

[Simonslimline]

Well the maximum Zs for a C 32 is 0.72 ohms so disconnection times will be met for the circuit, what sort of environment does the ring serve?

 

[jimmyray]

The disconnection times were met, and I looked at the Type B, which was double the Zs value, so would have been well below. The circuit serves an office(3 x twin socket outlets) a fire alarm vacuum sensor, and a desk in the corridor(2xtwin socket outlets)

 

[telectrix]

your boss probably has a surplus of type C.

 

[markc123]

...either that tel, or like you oldies - his eyes might be going, and he thought it was a B...

Haha.

:leaving:

 

[D Skelton]

Some people think that if it ain't in a domestic board they need to type C the lot. In reality, they are just poor designers most of the time.

 

[jimmyray]

It is a commercial(academic) building, so that would follow that logic. Just seemed weird.