MCB Lock Offs...

[the doctor]

nite nite chief:x

 

[welshwizard]

I ain't going to bed yet, Doc. :|

 

[steptoe]

i dont have any idea of the offical answer, nor do i really care for it that much, but heres my tuppence worth...

to isolate a circuit requires the live to be disconnected and locked off, a NEUTRAL is also a LIVE

to do it properly would require a DP MCB,

to do it practically would be the SP MCB we all use, as the main switch means killing every circuit thus causing untold inconvenience,(even in a household, never mind offices/factories etc.)

 

[The Godfather]

One has to draw the line somewhere:

DP would be best.

SP we normally accept as safe.

But we should always check for live, regardless of locking off.

 

[300TDI]

I see that when you buy a square D three phase dist board they throw in a free mcb locking toggle......they only recently started this as they have apeared in my last 2 or 3

 

[kme]

Now I seem to have read in the new bible, that if the system is TN, the neutral can be taken as being at earth potential; therefore only requiring SP disconnect.

As long as I`d tested polarity, I would personally only isolate at the MCB.

IMHO for what it`s worth.