3 phase ring main in a tool room. X6 16A sockets

[owensie]

Hi, I have been tasked with installing 3 phase ring main in a tool room. X6 16A sockets. Each pice if kit will pull no more than 5A. Planning on using 4mm SWA cable protected by a 63A breaker. Tool room dimensions are 7M X 5M. Any problems with this?

 

[Pete999]

Hi, I have been tasked with installing 3 phase ring main in a tool room. X6 16A sockets. Each pice if kit will pull no more than 5A. Planning on using 4mm SWA cable protected by a 63A breaker. Tool room dimensions are 7M X 5M. Any problems with this?

How many cores in the 4mm2

 

[owensie]

4 core

 

[Pete999]

4 core

Will this circuit be a a final circuit or a Distribution Ring? I see phasing problems, not the sort of circuit I would install. If it was my choice I would use some sort of Busbar 3 phase trunking and drop down to each outlet that requires power, using the appropriate trunking adaptors that are suitable for a W/Shop environment.

 

[westward10]

I think you need to reconsider your design, 16A sockets on a 63A protective device. As a ring final circuit, why?

 

[owensie]

63A Protect cable, each socket has its own 16A breaker. Supply's for a small drill, grinder, power saw and x2 extractors. The DB is in the room

 

[westward10]

It seems an odd thing to do but assuming each socket has additional rcd protection and is correctly designed with regard to vd and current carrying capacity it would be difficult to say it is incorrect, non-conventional maybe. BS7671 only references 30/32A ring final circuits whereby live conductors should not be less than 0.67 of the protective device so whether you can apply this I couldn't say for certain.

 

[owensie]

63A breaker isn't set in stone, was just thinking about the cable rating. Drill pulls less than 5A and the rest of the kit even less. Be rare more than 2 buts of kit will ever run at the same time. I am utilising gear we already have

 

[James]

I know a couple of companies that still have 200A rings round the units.

 

[owensie]

Thanks for the help, not my normal job role, was concerned about over looking something. Same tool room is to also have a 240 ring X6 16A sockets and a single 32A radial for a welder

 

[Lucien Nunes]

In practice it will be 100% fine, although it does seem a bit over-engineered for the present usage. Would run on two 20A radials, no local MCBs needed, and still have room for more.

 

[Strima]

I'd be looking at using 20 amp OCPD either ring or radial. Bear in mind that the devices will have no overload protection for the flexes.

 

[littlespark]

Maybe running load is under 5A, but startup current could be 3x that.

is a radial per machine not feasible?