Here is a picture of the fuse box. I want to put a hot water shower in. It will have an independent fuse trip. I'm guessing the top rail is black wire = live but what's the green wire? And where's the earth?

Hmmm, a worrying question, you need a sparks, guessing is not a thing to do with electricity.

Read this thread http://www.thaivisa.com/forum/topic/693630-how-to-make-your-thai-electrical-system-safe/

Green is the ground, you have a MEN installation.

The white wires on the block to the left are neutral.

When you plug in your new breaker the live will come from the bottom of the breaker.

You have no earth leakage protection. If you add a shower you should use either a single width RCBO for the shower circuit or add a front end RCBO (Safe-T-Cut).

EDIT What size (kW) shower do you intend installing, I see a 50A incomer is your meter a 15/45?

It's a 3.5kw shower. This is the breaker that was on it before in my old place. It was wired into the plug socket :-D (I didn't do it)

3,500 Watts (16A) on a 10A breaker was pushing it, it should have opened in between 100 and 500 seconds at that overload level.

I would use a 20A breaker and 2.5mm² cable to the shower. You should use an RCBO for safety, I think Square-D units will fit, but do check with your local outlet.

Ok. So the rcb plugs into the box . Right?

Thanks for your help.

Yes, your box takes plug-in (as opposed to DIN rail) MCBs and RCBOs.

With your level of knowledge I would not be attempting this myself, but you should be able to guide your sparks in his choice of parts.

If you want to have RCD protection for all circuits, do it as front end main breaker RCBO. If you just want for the shower, put on 20a breaker with 2.5mm2 wire (assuming 4500W or less) as all shower units these days have RCD protection already.

That's kinda what I was thinking, using you guys knowledge :-D

At the moment my sparks is the local odd job / motorcycle Taxi guy. Trying to get the wife networking a bit better, to find someone more qualified (if that's possible)

Where is ;ocal? There might be someone on here willing to give you a hand.

Nakhon Pathom

Sorry, too far for me. I live about 240 kilometers north of Bangkok.