Circuit Breakers & RCD. What's the difference?

[mottsy]

Hi all,

I'm not an electrician so please don't be offended if this is a silly question, but what is the difference between a MCB & RCD?

The only reason I ask is the my garage has a small consumer unit with two MCB's. (One for lights and one for power.) Should I get a RCD socket fitted or will the MCB do the same job?

Many thanks

Mottsy

 

[JohnD]

An MCB works like a fuse does, it cuts the circuit if there is an overload (or short circuit).

An RCD detects a fault to earth, e.g. you cut through your lawn-mower flex and grab the end, or your steam iron has a water leak inside which drips onto electric parts and starts to make the metal casing live. The RCD detects the current leak and cuts the power in a fraction of a second.

Lots of mini-consumer units made for garages include an RCD as the "main switch" and are available for less than £50. If you can lay your hands on a digital camera, put up a pic of the one you've got.

If you have sockets in your garage you are quite likely to use them with tools to work on the car ot garden, so an RCD is well worth having.

 

[mottsy]

Thanks John.

I'm at work so can't do a phot at the minute. The garage consumer unit is an old wired fuse type with the fuses replaced with MCB's. I don't think it will have a RCD fitted.

In view of this what are my options?

1. A new garage consumer unit with RCD fitted. (I assume this will then protect the two double sockets in the garage)

2. Is there a RCD that can be fitted between the consumer Unit and the fist socket. (Is this any better or cheaper than replacing the old consumer unit?)

3. Any other options.

Many thanks

Mottsy.

 

[Moss5]

http://www.screwfix.com/app/sfd/sea...&pn=1&pd=1&pi=1&cn=1&cd=1&q=garage+cu&x=9&y=4

http://www.toolstation.com/shop/Electrical/CircuitProtection/d190/sd2615

 

[Qedelec]

You could replace both double sockets with RCD protected outlets.
The one advantage is that if you trip the RCD only one socket goes out.
Less than £20 each.

 

[JohnD]

Option 2 is possible, so are the RCD sockets, but I think option 1 is best.

 

[mottsy]

Many thanks,

Another job on the "TO DO" list!

Mottsy