How would you meter (kwh) a ring final

[Jimmy090]

I have a customer that requested kwh meters on the socket circuits of an office lock he rents out,(rooms are rented separately).
There are two 16amp radials which obviously are not an issue,
But the ring mains 4 of are causing me a headache for obvious reasons!
The question is how would you guys go about metering kwh on a ring final?

 

[James]

I would either use a meter with ct coils and not disturb the original wiring.

or run a 6mm cable from breaker to meter then terminate the ring from the outgoing side of the meter.

 

[mainline]

I have a customer that requested kwh meters on the socket circuits of an office lock he rents out,(rooms are rented separately).
There are two 16amp radials which obviously are not an issue,
But the ring mains 4 of are causing me a headache for obvious reasons!
The question is how would you guys go about metering kwh on a ring final?

Din rail meter ?

https://www.jwsmartmeters.co.uk/product-category/din-rail-mounted-meters/

 

[davesparks]

There are two 16amp radials which obviously are not an issue,
But the ring mains 4 of are causing me a headache for obvious reasons!

What are the obvious reasons?

I can't see why metering a ring circuit is any more of a headache than metering a radial circuit?

 

[Jimmy090]

I would either use a meter with ct coils and not disturb the original wiring.

or run a 6mm cable from breaker to meter then terminate the ring from the outgoing side of the meter.

The 6mm idea was one I had, but another spark I know was saying that it wouldn’t be right as then the circuit goes from a radial to a ring!

 

[MJPD29]

It wouldnt matter, the 6mm is more than capable of carrying the required current and the ring can still be accessed at the metering point for testing purposes.

 

[DPG]

The 6mm idea was one I had, but another spark I know was saying that it wouldn’t be right as then the circuit goes from a radial to a ring!

It's still a ring, it's just that the output of the OCPD has been extended by a few inches before the connection to the two legs of the ring.

 

[James]

The 6mm idea was one I had, but another spark I know was saying that it wouldn’t be right as then the circuit goes from a radial to a ring!

Ask him what reg no. it contravenes or if it’s something that he has made up himself.

 

[DPG]

What are the obvious reasons?

I can't see why metering a ring circuit is any more of a headache than metering a radial circuit?

I think he means because of the current splitting between the two legs of the RFC.

 

[Jimmy090]

What are the obvious reasons?

I can't see why metering a ring circuit is any more of a headache than metering a radial circuit?

Because there’s two legs on a ring and only one on a radial, hence it can go straight through a standard 240v meter!

 

[Jimmy090]

Ask him what reg no. it contravenes or if it’s something that he has made up himself.

Yeah I couldn’t find anything in the regs! It’s good to have other people’s opinions though.

 

[James]

Also remember the regs are not mandatory, however if you deliberately deviate from them you may at some point need to prove that what you have done is at least equal in the protection it gives and preferably better. (Documentation is important here)

 

[Vortigern]

Din rail is ok and I have used it for RFC in a CU. The only snag the MCB/RCBO cant go onto the live bus bar, it has to have it's own supply from the din rail meter. So it can be a bit of a fiddle and would have go at the end of the MCB/RCBO if you see what I mean. But in its own separate CU/supply fairly straightforward. I am getting increasing requests for this type of thing. Next one is separating/metering an office unit from a three phase square d submain! Having to think about that one.

 

[Jimmy090]

Din rail is ok and I have used it for RFC in a CU. The only snag the MCB/RCBO cant go onto the live bus bar, it has to have it's own supply from the din rail meter. So it can be a bit of a fiddle and would have go at the end of the MCB/RCBO if you see what I mean. But in its own separate CU/supply fairly straightforward. I am getting increasing requests for this type of thing. Next one is separating/metering an office unit from a three phase square d submain! Having to think about that one.

I’ve done most of the customers units on separate 3phase meters with no issues, I’d basically run the office a supply to their own meter and db!

 

[davesparks]

Because there’s two legs on a ring and only one on a radial, hence it can go straight through a standard 240v meter!

The ring can go straight through a standard 240V meter too.
Just take a bit of 4mm to the incoming side of the meter and connect both legs of the ring to the outgoing side.