Single core vs Stranded

[gjh]

When quoting cable sizes does it matter if a cable is single core [one thick piece of copper] or stranded [multiple smaller strands].

Eg, i've added an electric towel rad to the bathroom and obviously need to bond it to the metal pipework in the bathroom. I have a reel of 10mm multi-strand [7 strands to be precise] cable, is this the same as 10mm single core.

Or am i being stupid and 10mm single core [in the sense of one thick strand of copper with a 10mm cross section] not actually exist as i can imagine it being impossible to work with!

Whilst on the subject, could I use 6mm multi-strand in the bathroom bonding instead as it would look a little neater [slightly smaller cable]. Also with the towel rad do I need to physically connect the bonding cable to the radiator itself or is it sufficient to just connect to the earth terminal in the wall mounted flex outlet [or do i need to do both]?

 

[andy]

above 2.5mm its stranded so it is more flexable. wouldnt like to have solid 16mm tails....

 

[ban-all-sheds]

Eg, i've added an electric towel rad to the bathroom and obviously need to bond it to the metal pipework in the bathroom. I have a reel of 10mm multi-strand [7 strands to be precise] cable, is this the same as 10mm single core.

Single/multi refer to the number of conductors in a cable, not the number of strands in each conductor.

This is a single-core cable, even though it is stranded:

This is not a single core cable, even though it has solid cores:

Whilst on the subject, could I use 6mm multi-strand in the bathroom bonding instead as it would look a little neater [slightly smaller cable].

You could use 4mm² if you wanted.

Also with the towel rad do I need to physically connect the bonding cable to the radiator itself or is it sufficient to just connect to the earth terminal in the wall mounted flex outlet [or do i need to do both]?

Just the earth terminal - as it is an electrical appliance the towel rail is not an extraneous-conductive-part, and therefore does not require bonding.

above 2.5mm its stranded so it is more flexable. wouldnt like to have solid 16mm tails....

AFAIK, all single-core cables are stranded....

 

[andy]

above 2.5mm its stranded so it is more flexable. wouldnt like to have solid 16mm tails....

AFAIK, all single-core cables are stranded....

your right. i was thinkin T+E

 

[mapj1]

To answer the original question, the number of strands per core (which is, I'm sure what he meant) is set by mechanical handling considerations (bend radius, flexibility, versus likely damage if too floppy). So flexes on appliences are more easily damaged or cut through, but more resilient against developing a 'broken neck' if kinked .
At high frequencies it starts to matter as the magnetic filed drives the current to flow in a skin on the surface, but at 50Hz, if no feromagnetic material around, this requires cables of many cm diameter to be a problem. (but note the national grid is multi-strand for this reason, but the conductors are arm and leg diameters.)

 

[ban-all-sheds]

Wonder what they use for DC transmision lines?

 

[Big_Spark]

Wonder what they use for DC transmision lines?

Stranded, usually 70 strands per cable, but on some it can be as high as 140 strands per cable.