Wiring a dryer, WMachine & Dwasher on same ring circuit

[et]

what would be the recommended cable size to wire up

Dryer P=2.4kW max
Washing machine P=2.2kW max
Dish Washer P=2.3kW max
-----------------
Total power P=6.9kW

and should it be done as a radial circuit or a ring circuit.

Note above system has been running for two years on 2.5mm ring circuit of round lengh 6m. Recently I inspected the wires and the where showing burn marks on the insulation. Can anyone recommend me what would be the best solution to this problem. Thank you very much in advance.

 

[breezer]

there own separate ring is fine even if they are all on at same time it will only draw 30 A

the burn marks i should say are cause by loose / bad connections.

why were you looking?

 

[andy]

Recently I inspected the wires and the where showing burn marks on the insulation.

on the appliance cable or the ring main cable?

if the appliance then itll have nothin to do with the ring

 

[et]

there own separate ring is fine even if they are all on at same time it will only draw 30 A

the burn marks i should say are cause by loose / bad connections.

why were you looking?

even if the circuit is made of 2.5mm which only has a 24A current rating

smell the burning

 

[et]

in the ring mains cable

I am considering replacing the whole circuit but not sure whether to doit with 2.5mm or 6mm, and if I use 6mm whether to make it a radial circuit or a ring circuit (6mm a bit thick for ring I think)

 

[breezer]

you will have a hard job getting two 6mm cables into a socket, as i said its very likely a loose or bad connection that is the cause

 

[plugwash]

a few more questions

1: is the burning only in a small area near accessory or joint
2: are the loads all close to the same end of the ring?


personally if you are going to rewire the appliances and you have the space in your CU i would go for 3 seperate 16A 2.5mm radials its only a tiny bit more cable than a single ring after all

 

[andy]

even if the circuit is made of 2.5mm which only has a 24A current rating

smell the burning

2.5 cable has a rating on 27 amps

a ring uses 2 2.5mm cables, givin a total CSA of 5MM. the to 2.5mm cables combined have a rating of 54A. in other words, a 2.5mm ring is able to take the load

 

[plugwash]

even if the circuit is made of 2.5mm which only has a 24A current rating

smell the burning

2.5 cable has a rating on 27 amps

a ring uses 2 2.5mm cables, givin a total CSA of 5MM. the to 2.5mm cables combined have a rating of 54A. in other words, a 2.5mm ring is able to take the load

only if the loading is in the exact centre of the ring
the IEE say each cable in a ring should be rated for at least two thirds of the fuse/breaker rating

this is ok in most cases but there could still be problems if a lot of high power appliances are located close to one end

 

[biblio]

andrew2022 said:
'a ring uses 2 2.5mm cables, givin a total CSA of 5MM. the two 2.5mm cables combined have a rating of 54A'

(The Electrician's Guide' Table 4.7, page 63) Can I assume these figures apply in principle for both ring circuits and for radial circuits, but that a ring can be rated at double the capacity?

(is CSA the cross-sectional area?)

 

[ban-all-sheds]

even if the circuit is made of 2.5mm which only has a 24A current rating

As has been pointed out, it's a ring circuit.

Read this: http://www.iee.org/Publish/WireRegs/Amd1andRC.pdf

 

[et]

Q: would a single 6mm radial wire be safe, I don't feel confident with fitting 2.5mm again, to close for comfort. Any advise guys.

Breezer yes a loose connection could be the problem here but all screws are tight on the mains. Could a loose connection on the appliance be the cause. Or could heavy use of the system be the real reason as all three have been running together fairly regular.

Q: Could the fact that they are all at one end of the circuit be putting more strain on one of the wires, therefore all the load running through that wire.

Q: Would it be wiser to use the spare space and create a separate ring for one of the appliances, and place the other two together there for reducing the load. or would just one bigger cable do it.

a few more questions

1: is the burning only in a small area near accessory or joint
2: are the loads all close to the same end of the ring?


personally if you are going to rewire the appliances and you have the space in your CU i would go for 3 seperate 16A 2.5mm radials its only a tiny bit more cable than a single ring after all

in answer to your question

1.- the burning is on live wire only at mcb end [only one of the wires]
2.- yes, all three sockets are next to each other 1 double, 1 single, could say that they are at middle of ring.
3.- possible but only got space for one more mcb.

only if the loading is in the exact centre of the ring
the IEE say each cable in a ring should be rated for at least two thirds of the fuse/breaker rating

this is ok in most cases but there could still be problems if a lot of high power appliances are located close to one end

A: 32A MCB, 27A cable rating should have been more than enough, unless the 30A load is not split evenly. Is that what you mean

As has been pointed out, it's a ring circuit.

Read this: http://www.iee.org/Publish/WireRegs/Amd1andRC.pdf[/QUOTE]

Thanks the article was very useful, recommend for others to read.

 

[breezer]

as i said you will no be able to make a 6mm ring or radial, be my guest to try the cables will not fit.

i still say its a loose / bad connection, but yes if you can split them up do so, but there is no need (other than to put your mind at rest) mind you you could always opt to re wire it in 2.5 and only use any 2 at the same time

 

[Damocles]

No burning on neutral? Unless something very strange is going on, the neutral in the cable should be carrying exactly the same current as the live. So something must be different about the live cable circuit than about the neutral cable circuit.

Are you sure one of the sockets does not have a bad connection with one pin on a plug, or a wire inside a plug might be loose? Do any plugs get hot while their equipment is operating? Or even more interesting if plugs get hot while they are not drawing current. (heat coming from something nearby through cable/socket connection?)

trapped insulation where a cable goes into the screw on the socket?

 

[ban-all-sheds]

Q: would a single 6mm radial wire be safe, I don't feel confident with fitting 2.5mm again, to close for comfort. Any advise guys.

I you don't want a 2.5mm² ring, why not a 4mm² radial? Why the jump to 6mm²?

Q: Could the fact that they are all at one end of the circuit be putting more strain on one of the wires, therefore all the load running through that wire.

yes, all three sockets are next to each other 1 double, 1 single, could say that they are at middle of ring.

Which is it? Are these loads roughly halfway round the ring, or not?