16A MCB in the consumer unit?

[cdh]

There's a cable from the consumer unit to the garden shed (1.5 SWA cable) at a depth of 18 inches and running 25m long which runs a shed light operated by a pullcord switch.

I've got a spare rcd weather proof socket which I would like to install in the shed and possibly use the same cable.

I've been told if I use a 16A MCB in the consumer unit and a fused spur (with 3A or 5A fuse) installed in the shed for the light, it should be OK.

Does anyone know if this is right?

Thanks

 

[ban-all-sheds]

There's a cable from the consumer unit to the garden shed (1.5 SWA cable) at a depth of 18 inches and running 25m long which runs a shed light operated by a pullcord switch.

What breaker is it on right now?

I've got a spare rcd weather proof socket which I would like to install in the shed and possibly use the same cable.

I've been told if I use a 16A MCB in the consumer unit and a fused spur (with 3A or 5A fuse) installed in the shed for the light, it should be OK.

Does anyone know if this is right?

• //www.diynot.com/wiki/electrics:mcbtocable
  
  
• http://www.tlc-direct.co.uk/Book/4.3.1.htm
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf
  
  
• http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html
  
  
• http://www.tlc-direct.co.uk/Book/5.3.1.htm
  
  
• http://www.tlc-direct.co.uk/Book/8.1.1.htm - testing is very important if you're changing an MCB, as you'll see when you read the info above about voltage drop and earth fault loop impedance.
  
  
• And changing an MCB is notifiable.
  
  

 

[cdh]

It's on a 6A

 

[ban-all-sheds]

OK - yes, you would need an FCU for the lights at the other end, and as I said changing the MCB is notifiable and really should not be done without checking that the existing cable is OK for voltage drop and above all fault-loop impedance.

If you read the information linked to above you'll see why.

 

[plugwash]

on 25M run you will be way out of spec on volt drop.