Consumer Unit issue

[Felipesed]

I have just moved in to a rented house, and have been checking the electrical supply.

There is no earth bonding, no 3-pin sockets,and I am getting shocks from the metallic part of any audio and satellite cable connectors.

I looked at the CU and it would appear to me that the Live feed has been incorrectly connected (apart from the rats nest that was in the CU!).

I have marked the Live with red tape,and attach photos.

Would anyone care to comment on my findings please.

[Crossy]

If you are certain that the red taped cable is the live, then yes it's the wrong way round and you need to get a man in to fix it.

How did you determine the live wire??

Shocks from AV kit is invariably via input filter capacitors, swapping your supply may or may not fix it, but a simple earth rod coupled to a case screw will kill the tickles dead.

[Felipesed]

Thanks for the reply. Determined by multimeter.

I swapped cables over, not much difference in the shocks though.

Next step is to fit a proper earth rod, although none of the house sockets are 3-wire.

I want to fit an RCD, but I am a bit concerned that there may be many "borrowed" neutrals which might cause problems. The wiring is a bit hit and miss.

Might be better to go for individual RCBs do you think?

[Crossy]

A single RCBO replacing your main switch is probably the easiest way to go, it won't worry about borrowed neutrals. Haco make them to fit your CU.

There are evidently some grounds in place and possibly a rod so it's worth investigating where it is.

With a metal CU I would not go about any activities 'live', get a local sparks to do the deed.

[Felipesed]

Many thanks.

I have seen a 63A Safe-T-Cut for about 1250 Baht in Home Expert Shop, seems too cheap.

Is that what you had in mind? Would this replace the 50A Mitsubishi breaker currently fitted between meter and CU, or should the RCD be fitted between this breaker and the CU?

Found one ground rod, but only seems to connect to external water heater, pump for well water and pump for water supply to house. All these are in a separate room. The earth wire also looks a bit small for my liking, and is also black in colour. Seems they had not heard of wiring colour codes when house was built!

Regards

[Crossy]

OK. If I'm reading this correctly you have an additional 2 pole 50A MCB between the CU and meter.

That being the case you can replace the 2-pole main switch in the CU with an RCD (it provides earth leakage protection only, overload will be provided by the Misubishi breaker).

Have a look here http://www.hacothailand.com/product-engshow.php?Page=7&setype=3&setype2=&txtsearch= the devices you want will be in the R7 series probably R7-263-30 unfortunately the 'detail' links don't seem to work but you need an RCD with a 30mA trip current and a rated current of more than 50A

[Felipesed]

Thanks very much. You did read correctly.

I will get one tomorrow.

If you are ever in Chiangmai, let me know and the beers are on me.

[Forkinhades]

I want to fit an RCD, but I am a bit concerned that there may be many "borrowed" neutrals which might cause problems. The wiring is a bit hit and miss.

Might be better to go for individual RCBs do you think?

A main RCD will work fine, with or without borrowed neutrals. Borrowed neutrals only really become dangerous when somebody is working on the circuitry.

An individual RCBO will trip if you have borrowed neutrals, more of a nuisance than anything else.

[Felipesed]

RCD as recommended bought and fitted, no problems so far.

Also bought earthing rod and wire; that is the next job. Rain stopping outdoor play at the moment.

Thanks for the help.