I completely rewired my workshop which is in an extension to the house.

 

I have two (radial) circuits:

• Socket circuit with 4 sqmm wires which tails off to 2.5 sqmm in places
• Light circuit 1.5 sqmm wire; total consumption less than 150 W

 

I don't have a separate CU in my shop and only have one cable (3 X 4 sqmm) coming in from the house's CU. This cable is protected with a 20 A breaker.

 

Questions: Would it be necessary (or recommend) to protect the light circuit that only has 1.5 sqmm wires with a lower breaker i.e. 10 A or 6 A, rather than connecting it directly to the socket circuit?  Would a simple a 2P/ 10 A breaker in my shop be sensible in order to separate the light circuit?

What is your idea?

I guess if something needs extra protection then it will be the sockets and not the light? Or not?

Like it something goes wrong with a tool in your workshop then you want that the tool is disconnected but probably you still want that the light is on.

With a 20A breaker at the house end you should be fine. 

 

1.5mm2 is good for a load of 16A so 20A isn't really going to bother it and it would be a short term overload anyway until the 20A breaker operated.

 

If you have a very long run to the shed you might run in to issues with the adiabatic equation but I'd leave it as it is.

 

What you wouldn't want to do is up that 20A breaker (to support your new industrial welder) without putting a baby CU in the shop.

Thank you @Crossy for confirming this. Much appreciated!

 

Good practical point @OneMoreFarang.

 

I'll see if there are some reasonably priced mini CUs to put in the shop. Now a new industrial welder might might well be an option. :-)

 

 

I got a baby HiTek CU with a 30A 2-pole incomer and 20A + 16A 1-pole MCBs for < 500 Baht at MegaHome.

2 minutes ago, Crossy said:

I got a baby HiTek CU with a 30A 2-pole incomer and 20A + 16A 1-pole MCBs for < 500 Baht at MegaHome.

Nice. Sounds good.