how long can a spur cable be

[oldandtired]

I want t run a spur(using 2.5mm cable) from a socket on a ring main . how long can the spur cable be?

 

[James]

There are no specific regs as to how long it is.
However it will have to meet regulations regarding volt drop calculations.

 

[telectrix]

as long as the Zs at the spurred socket is below 1.09 ohms it's good (assuming a 32A type B MCB), and of course VD below 5%. (11.5V).

 

[Dustydazzler]

If if longer than a drum of 2.5 then its too far...
In all seriousness if we are talking domesticated dwellings then it’s unlikely to ever exceed maximum permissible lengthy

 

[oldandtired]

There are no specific regs as to how long it is.
However it will have to meet regulations regarding volt drop calculations.

not sure how to do v/drop calc , the spur will be approx 4m. i want to run a tumble dryer from the spurred socket

 

[Pete999]

I want t run a spur(using 2.5mm cable) from a socket on a ring main . how long can the spur cable be?

Lots of imponderables to deal with Voltage at final destination ( have any volt drop calculations been done?)
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not sure how to do v/drop calc , the spur will be approx 4m. i want to run a tumble dryer from the spurred socket

What is the Electrical load of the tumble dryer?

 

[telectrix]

if you're going to run 4m 2.5 cable, why not run 2 cables and extend ring in existing socket using wagos or ideal in line splice connectors. it's less than a fiver for extra materials

 

[oldandtired]

Lots of imponderables to deal with Voltage at final destination ( have any volt drop calculations been done?)
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What is the Electrical load of the tumble dryer?
[/QU

if you're going to run 4m 2.5 cable, why not run 2 cables and extend ring in existing socket using wagos or ideal in line splice connectors. it's less than a fiver for extra materials

thought about extending ring but nearest point to break into it easily and fit conector block will be 6/7m . The 4m length would be fed from back of socket.

 

[telectrix]

why can't you run 2 legs from the socket. joint in back box?like here?

 

[Pete999]

thought about extending ring but nearest point to break into it easily and fit conector block will be 6/7m . The 4m length would be fed from back of socket.

You will need to be certain that the socket you intend spurring from is actually part of a RFC and not already a spur from the RFC, and your addition is NOT a spur from an existing Spur

 

[oldandtired]

You will need to be certain that the socket you intend spurring from is actually part of a RFC and not already a spur from the RFC, and your addition is NOT a spur from an existing Spur

the socket I am intending to spur from is part of the ring main. and is not a spur
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if you're going to run 4m 2.5 cable, why not run 2 cables and extend ring in existing socket using wagos or ideal in line splice connectors. it's less than a fiver for extra materials

thanks , will have another look at options

 

[telectrix]

the socket I am intending to spur from is part of the ring main. and is not a spur
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thanks , will have another look at options

see picture in post #9. it's 1 I did last year. obviouslytrhe red/blacks are existing. the brown/blues are my rfc extension., clipped about 3m under floor in crawl space. ( this is what thin apprentices are for. ).

 

[Deleted member 105166]

In all seriousness if we are talking domesticated dwellings then it’s unlikely to ever exceed maximum permissible lengthy

Don't say that, those none the wiser will take as licence to take a 2.5 T/E spur to their domesticated garden shed or barbeque position at the bottom of the garden!

 

[Dustydazzler]

Don't say that, those none the wiser will take as licence to take a 2.5 T/E spur to their domesticated garden shed or barbeque position at the bottom of the garden!

I should have said ‘within’ the domesticated dwelling

 

[sparks1234]

if you're going to run 4m 2.5 cable, why not run 2 cables and extend ring in existing socket using wagos or ideal in line splice connectors. it's less than a fiver for extra materials

Because there is no point

 

[telectrix]

Because there is no point

because today he wants to run a tumble dryer; next week he may want a dishwasher and a washing machine in the same location. as it's only a 4m run, why skimp for the sake of a few quid?

 

[sparks1234]

because today he wants to run a tumble dryer; next week he may want a dishwasher and a washing machine in the same location. as it's only a 4m run, why skimp for the sake of a few quid?

nope

because today he wants to run a tumble dryer; next week he may want a dishwasher and a washing machine in the same location. as it's only a 4m run, why skimp for the sake of a few quid?

but at the moment he wants to run a tumble dryer, end of, perhaps he might want a sauna, who knows, but for a tumble dryer, its fine

 

[fairlight]

because today he wants to run a tumble dryer; next week he may want a dishwasher and a washing machine in the same location. as it's only a 4m run, why skimp for the sake of a few quid?

There would be no reason why a WM and DW could not both run on a double socket from a properly wired spur.

 

[telectrix]

nope

but at the moment he wants to run a tumble dryer, end of, perhaps he might want a sauna, who knows, but for a tumble dryer, its fine

don't dispute that, but for the cost involved in extending the rfc, why limit the work to a single accessory point.

 

[Zerax]

That's a hell of a big cupboard he has there... room for a tumble drier, dishwasher, washing machine and now a sauna !!

 

[telectrix]

That's a hell of a big cupboard he has there... room for a tumble drier, dishwasher, washing machine and now a sauna !!

he 's got a Tardis.

 

[sparks1234]

Extend it, but there is no point, its a waste of materials

 

[telectrix]

There would be no reason why a WM and DW could not both run on a double socket from a properly wired spur.

so you'd be happy pulling 4.5 kW off a double socket, rated at 20A?

 

[sparks1234]

Its a tumble dryer, unless I've missed something it won't be 4.5Kw, even if it was, its still not 20 amps, why do you think spurs are legal Telectrix, you're over complicating it, no need to extend the ring

 

[fairlight]

so you'd be happy pulling 4.5 kW off a double socket, rated at 20A?

There is no reason why not, two laundry appliances are often plugged into a double socket and neither appliance will pull full load constantly even when running together. 4.5kw equates to 19.6a @ 230v, in practice it's likely to be 18.75a @ 240v. I would not claim a spur would be the best way to do it, but neither is it wrong, especially as the OP has stated the intention is only to run one appliance.

 

[telectrix]

Its a tumble dryer, unless I've missed something it won't be 4.5Kw, even if it was, its still not 20 amps, why do you think spurs are legal Telectrix, you're over complicating it, no need to extend the ring

mupost was in reply to fairlight's post re tumble dryer and washing machine both on a twin outlet. each will have a 2.2kW heater. add a bit for the restof the machines'bits.... 4.5kW.
i don't disputethatfor 1 appliance aspur complies, but that the cost and effort to extend ring is minimal.
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this had a washer and tumble dryer connected.

 

[fairlight]

i don't disputethatfor 1 appliance aspur complies, but that the cost and effort to extend ring is minimal.

It complies for two appliances plugged into a double socket on a spur. A preference for a ring is a perfectly legitimate point of view. But to suggest that a spur supplying a twin socket does not comply is plain wrong. And regardless of a ring or spur, the load on the socket will be the same.

 

[telectrix]

I'm not arguing that it complies or not. just that for what's involved, extending the rfc would be my preference. with a spur, if OP were to want another outlet adding at some time, he'd have to retro fit a FCU.

 

[fairlight]

The pic you have posted above of the burnt out socket shows both line pins overheated, this is probably due to a poor quality socket or plug top, and with those two appliances plugged into that twin socket it would make not a scrap of difference whether it was on a ring or a spur.

 

[Zerax]

I'm not arguing that it complies or not. just that for what's involved, extending the rfc would be my preference. with a spur, if OP were to want another outlet adding at some time, he'd have to retro fit a FCU.

I'm with you on this one Tele... I'll always try to extend a ring rather than spur.