I am going to get a couple of these as I currently don't use them. But what do they actually do to help keep the rig safer? I thought they tripped if you used too much power? Am I............correct?

No, their main role is to prevent electrocution or fire, by sensing any flow of electrical current to Earth. For example, somebody touching a live wire, or the metal case of an appliance (Or your lighting stand!) becoming live due to an internal fault.

They are usually used for outdoor appliances such as hedge trimmers to protect against electrocution in the event of a cable being cut but they are ideal for our line of work.

Most modern buildings and houses have these trips built in to the fuse box or electrical distribution board, but a lot of older buildings still do not, and so carrying them around with us and using one is a very good idea.

Of course this isn't an excuse for PAT testing or regular maintanance and checks of your leads and cables, but it gives you added defence should the worst happen.

Some of the more expensive ones also protect against circuit overload, but that isn't their main objective. Those devices that protect against overload are known as circuit breakers and often provide an easily resetable alternative to the old ceramic or wired fuses in the fuseboxes.

So a good idea to invest in a plug in, or wired RCD, they do save lives - Not a bad investment for under a tenner

Yep, I'll get em ASAP.

I agree its not an excuse for checks (I do loads, probably too many!) and PAT (which I have)

Cheers

I have two, always get the plug type as if you get the socket type you tend to forget them at the end of the gig, even after doing an idiot check.

I use them 2, but I use plug in 1 that plugs into the wall, then I plug a Surge Protector into it.

We have 2 extension leads both with RCD’s fitted, one for all the lighting & the other for sound. Had a little problem at one venue where the sockets were tucked up tight under the sound limmeter, not enough room to plug the RCD’s in. Luckily we had a couple of cheep 4 way extension leads, we could use between the socket & our normal power leads.