Have a 100mA RCD, How can I improve to 30mA (and do I need to)

[SFK]

In my Garage I noticed that my Merlin Gerin Consumer unit has a 100mA RCCB protecting the MCBs circuits.

EDIT: This CU has its own independent supply, straight from DNO/mains, with its own meter, and no prior RCD.

Ignore the labels for large machines, these have all long gone, and the three phase reduced to one phase (all before my time). And although all socket circuits are rings - it is noted that they are 20A MCBs.

I am using sockets for Bandsaw, table sander, hand tools and lawn mower (outside).

So to my questions - I use the Sockets for small workshop tools, and I 'think' I would prefer to have 30mA protection rather than 100mA.

1) Am I correct in this assumption of wanting 30mA - or can I stay with 100mA protection?

2) If I wish to change to 30mA can I simply get the MCBs on only the 'Sockets' changed to RCBOs (this unit can also take Schneider RCBOs).

Thanks, SFK

 

[winston1]

First of all how is this garage CU fed? If it is already RCD protected in the house at 30mA you don't need to do anything.

 

[SFK]

Sorry should have said this garage is - straight from mains, to its own meter, to this CU.
No RCD prior to this CU.
SFK

 

[winston1]

In that case I would put in RCBOs as you suggest.

 

[SFK]

Winston,
With thanks for that.

My MCBs state that they are "B20"
Whereas most/all of the Schneider RCBOs state that they are "C20",

What is my risk in changing from Type B to Type C?

SFK

 

[ericmark]

In theroy it depends on the line - neutral loop impedance, I practice I would not worry.

 

[SFK]

With thanks to all.
Will have a look and see what I can get.
Sfk