Cables ran in parallel?

[dobo99]

Just wondering what you would put on PIR. Supply to separate DB is two 10mm twin and earths ran together, never seen it before ?:|

 

[batty]

Is that three phase dobbo.

Batty

 

[dobo99]

No mate single

 

[batty]

I have seen it at a butchers shop I used to work at but it was for a three phase supply. Not sure what reg it contravenes.

Batty

 

[dobo99]

No i wasnt either. Was thinking of noting it on the sheet just to cover myself but cant find anything glaringly obvious in the red book to back it up. :|

 

[Andy™]

you can double up on cables. easier if they are both the same size. cant remember all the regs on it, but im sure someone will know them

 

[binky]

There was an article about sizing CPCs under such circumstances in the last NICEIC mag - have a look at website - ergo nothing wrong with the practice. Basically it adds up to 20mm sq so obviously someone didn't have any 16mm cable to hand. Would make note ad leave it at that.

 

[green-hornet]

I agree with binky, it does not really contravene any regulations providing they are clearly marked and terminated correctly.I sometimes do a continuity check and put the readings on the PIR for future reference.

One of the more common practices I have seen is individual 2.5 bunched together to provide neatral for a block of flats.The live and earth being single core 16mm, no idea why they used seperate neutrals unless they ran out!

 

[binky]

One of the more common practices I have seen is individual 2.5 bunched together to provide neatral for a block of flats.The live and earth being single core 16mm, no idea why they used seperate neutrals unless they ran out!

Harmonic currents perhaps ?:| ? :| ?:| ? :| ?:|

 

[Barx]

Seen a bunch of 1.5 double insulated blues in place for the neutral tail in a house. In fact, seen it twice (not sure if it was same guy who done em, different areas). Replaced anyway. just didn't seem right.

 

[Andy™]

its kinda similar to a split con layout - singe core live and stranded neutrals

 

[dobo99]

Thanks guy`s ill just note it on the cert

Now for some :Y

 

[Badger]

Harmonic currents perhaps ?:| ? :| ?:| ? :| ?:|

no it was what they had spare after re stringing their guitars :^O :^O

 

[Evans Electric]

Called them Parallel feeders years ago, used to be done with SWA ,s often in aluminium. Cables must be the same size and run together. You can't run a 10mm and a 6mm to equal 16mm. Bit odd in your case but it does the job.

Deke

 

[SPECIAL LOCATION]

Just wondering what you would put on PIR. Supply to separate DB is two 10mm twin and earths ran together, never seen it before ?:|

Hi Dobo99

The regs you need to check.. to make sure your installation complies with 17th BS7671 are as follows...

Page 75:-

433.4 Overload protection of conductors in parrallel.

433.4.1 Equal current sharing between parallel conductors.

433.4.2 Unequal current sharing between parallel conductors

Page 76:-

434.4 fault current protection of conductors in parrallel.

Page 104:-

523.8 current carrying capacity of cables conductors in parallel.

As a quick guide....

# It is preferable to have same CSA, material, & length of parallel conductors

# NO branches in one leg of parallel conductor. {excluding ring circuits!}

# You should balance load equally across conductors.

# You can have single protection device.

# If single protective device not effective then multiple protective devices for each leg of parallel conductor.

# For more than two conductors in parallel a fault protective device shall be fitted at supply and load both ends of each parallel conductor.

# Where adequate current sharing not possible or more than four conductors needed consideration of using bus-bar trunking should be made.

Also Pages 353