Ring Final Circuit - spurs only

[UNG]

Because it is a safe method of isolation, you can't get more isolated than fully disconnected.

Really that was the point I was making to the post I quoted to see what response SJW would post as a reply

 

[davesparks]

Whatever standard and non-standard are.

In this situation standard refers to the standard circuits described in bs7671 and associated publications. They are best described in the on-site guide I believe.
Standard circuits refers to the 32A ring final, 20A radial and 32A radial circuits described in those publications. Details are given for minimum cable size, maximum length of cable etc etc

Non-standard refers to any other circuit which you will have designed yourself.

 

[nicebutdim]

Sockets are not for permanently used appliances. They are to be plugged in and out. Permanently wired in appliance need to be hard wired. And that in theory includes a 24/7/365 fridge.

Manufacturers have ensured that there's nothing permanent about fridges, nor any other white goods, and a fridge is one appliance that I'd never consider supplying from a ring in any new installation.

This one appliance is very likely to be the greatest source of trouble in your theoretical circuit, despite its relatively low power consumption, and for reasons you've failed to take into account.

 

[John-SJW]

And then, when the homeowner needs a new fridge, he has to get a sparky out to disconnect the old one and reconnect the new one.

Makes perfect sense to use a plug, especially since it will come with a pre fitted one.

Yep. Some fridges use 750 watt. That needs hard wiring.

 

[John-SJW]

Assuming the average ring circuit has 10 sockets on it and you save 3m of cable per socket that's a saving of 30m of cable.
At current prices that could be about £25 saved.

Depending on your preference for joint boxes they could realistically cost you £25.
Then you need to consider the additional time involved.

Other considerations are best practice, it is generally accepted that best practice is to avoid unnecessary joints in cables, every joint being a potential point of failure.

Also you need to consider maintainence and fault finding, it is going to be a lot harder to fault find a ring circuit where you can't readily get to the ring itself.

MF jboxes.

 

[DPG]

Yep. Some fridges use 750 watt. That needs hard wiring.

What? A fridge that takes 750 Watts must be hard wired and not use a plug/socket?

Please explain.

 

[John-SJW]

So why do some manufacturers consider removal of the plug from the socket is safe isolation of the appliance when they need to carry out warranty work. Back to the old you can't cut the plug off without voiding the warranty debate

Manufacturers come out with all sorts of nonsense at times

 

[DPG]

Manufacturers come out with all sorts of nonsense at times

It's not nonsense. A plug and socket is classed as acceptable for safe isolation. Check the regs

 

[nicebutdim]

Yep. Some fridges use 750 watt. That needs hard wiring.

In case it gets missed, I'll repeat the question from @DPG

Can you explain why this fridge might need to be hardwired?

 

[davesparks]

Yep. Some fridges use 750 watt. That needs hard wiring.

No it doesn't, the requirement for appliances of any power rating to be hard wired.

 

[John-SJW]

Why would you us a ring for this? Dedicated circuits for heavy appliances are normally better off installed as radials.

A ring serving only heavy appliances may be the better solution. And a cheaper solution if say using AFDDs. Then only one needs to be used.

Three radials say with expensive AFDDs or RCBO's, can be quite expensive for no to little gain over a ring.

 

[nicebutdim]

A ring serving only heavy appliances may be the better solution. And a cheaper solution if say using AFDDs. Then only one needs to be used.

Three radials say with expensive AFDDs or RCBO's, can be quite expensive for no to little gain over a ring.

Better in what regard?

Certainly not in terms of dealing with earth leakage, where 30mA protection is mandated at source. At the present time, there's no requirent to fit AFDDs for circuits suppling applainces, in the vast majority of domestic installations, so their realtively high cost (for now) is of little consequence.

 

[John-SJW]

Can you explain why this fridge might need to be hardwired?

Because it works 24/7/365, drawing a fair bit of amps. Sockets were not intended or designed for such permanent use. No one would wire a 3kW immersion on a 13A socket. I have seen large fridge sockets get brown with heat.

 

[DPG]

A ring serving only heavy appliances may be the better solution. And a cheaper solution if say using AFDDs. Then only one needs to be used.

Three radials say with expensive AFDDs or RCBO's, can be quite expensive for no to little gain over a ring.

You're just turning this into the thread that was closed last week.

 

[DPG]

Because it works 24/7/365, drawing a fair bit of amps. Sockets were not intended or designed for such permanent use. No one would wire a 3kW immersion on a 13A socket. I have seen large fridge sockets get brown with heat.

If a plug and socket have a problem with 750 Watts then you haven't fitted them properly.

 

[Fazz711]

Because it works 24/7/365, drawing a fair bit of amps. Sockets were not intended or designed for such permanent use. No one would wire a 3kW immersion on a 13A socket. I have seen large fridge sockets get brown with heat.

Surely a fridge Dosnt draw full power all the time.
It is switching off and on when it needs to cool

 

[nicebutdim]

Because it works 24/7/365, drawing a fair bit of amps. Sockets were not intended or designed for such permanent use. No one would wire a 3kW immersion on a 13A socket. I have seen large fridge sockets get brown with heat.

'Drawing a fair bit of amps' at 750W? 3.26A to be precise.

No one would place a 3kW immersion heater on a 13A socket because doing so would involve terrible design, exceed its 13A rating and also would be out of step with the regulatory reccomendation that all fixed loads over 2kW be placed on their own dedicated circuit.

As such, any comparision between a 750W fridge and 3kW immersion heater is pointless.

Would you consider powering a 3kW immersion heater from your theoretical 'ring final busbar'?

 

[davesparks]

A ring serving only heavy appliances may be the better solution. And a cheaper solution if say using AFDDs. Then only one needs to be used.

Three radials say with expensive AFDDs or RCBO's, can be quite expensive for no to little gain over a ring.

Why has one appliance circuit suddenly become 3? You're moving the goal posts to suit your point.

Yes of course 1 circuit is cheaper to install than 3, that's pretty obvious.

 

[davesparks]

No one would wire a 3kW immersion on a 13A socket.

As a temporary measure most people will do exactly that, but no you wouldn't normally as a permanent connection.

But an immersion heater is very different to a fridge.
A fridge is a stand-alone appliance, supplied with a flexible cable and plug and is intended to be connected by that cable and plug.
An immersion heater is a component to be installed into a larger system, it is supplied without any cable or plug and is designed to be connected, by whatever means is appropriate, by whoever assembles that larger system.
There's nothing to say that immersion heater can't be connected by a plug and socket, but I think most of us would be more likely to use a 15A or 16A socket rather than a 13A one.

I have seen large fridge sockets get brown with heat.

We've all seen sockets burned out. Not that long ago I had to replace a 63A socket which had completely burned out and had a plug stuck in it. This doesn't prove anything.

 

[John-SJW]

Why has one appliance circuit suddenly become 3?

I never mentioned a number, you did.