Maximum size MCB on a 16A socket outlet

[scotsparky]

Thanks guys I'm still sure the reg stated somewhere or other that a 20A MCB is the maximum MCB size for a 16A Socket outlet! I'm that sad i've just ordered guidance note 1 to find it! I know it doesn't sound right but i'm 99.9% sure that I've seen it somewhere in the regs! It's a pain because my regs book it in work in the van for the weekend!

ok being the devils advocate what happens if its a 1.5mm cable? do you install the MCB to protect the socket or cable?
This is basic stuff. The overcurrent device has to protect the cable but be suitable for the design current.

 

[Outspoken]

Hi guys this is my first post asking a question so here goes!

I'm currently having a debate with my boss who is adement that you can only have a 16A MCB on a 16A socket outlet. I'm sure I've seen somewhere in the regs or OSG that the maximum size MCB is a 20A on a 16A socket (Don't ask me why doesn't quite make sense) 7

I haven't got Guidance note 1 to hand but have found it is in there just wondering whether anyone knows where in the OSG or the Regs I could find it!

Would be a real help Thanks Jamie Morris

Jamie, is this socket for a caravan or other leisure equipment..if it is not, then you can ignore all those who point you to section 708 as that is for "Electrical Installations in Caravan/Camping Parks and Similar Locations". If you are installing this socket in an industrial/commercial location then s708 does not apply to your situation.

Realistically the most appropriate would likely be s705 (Agricultural and Horticultural Premises) because 705.533.1 deals with socket outlets and as Commando Plugs are BS EN 60309 standard, the 20A MCB protection does not relate as this is for BS 1363 socket outlets.

As BS EN 60309 outlets are designed to be used in industrial and related environments you need to consider the equipment that will be used in the outlet(s) and the cable and the over-current protective device should be so selected as to allow for the operating characteristics of the equipment. I would suggest that the cable should be a minimum of 4mm², possibly up to 6mm² depending on the distance between supply and equipment, ideally not the socket as some equipment may be on long leads that may add to the volt drop and thus the current loads on the circuit.(You have to judge this for each install as each are different). The ideal over-current device would be a 16A MCB but select either B,C or D type depending on the load applied and it's inrush currents at start up.

If this is movable equipment and not something that is normally left in one spot and not moved by one person, I would suggest that perhaps the installation of an RCD for added protection would be good practice and give greater protection should the lead become damaged.