3 core and earth 1.5mm flex cable

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I need to buy the above for UFH wired thermostats. Does that mean I need to buy cables with 4 wires in it or does the the cables include the earth? Maplins are doing a closing down sale and tempted to buy some that I need but all they are saying is that it is 13 amp cable. Would that match 1.5mm?
 
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Hi

That will be 4-core ,a supply and a switched live

Normally i'd use 5-core for stats ,but 4 will do depending on the type of stat
 
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I need to buy the above for UFH wired thermostats. Does that mean I need to buy cables with 4 wires in it or does the the cables include the earth? Maplins are doing a closing down sale and tempted to buy some that I need but all they are saying is that it is 13 amp cable. Would that match 1.5mm?

For "installation" cable, the number of cores quoted does not usually include the earth - hence Twin+Earth, 3-Core+Earth. For flex, the number of cores quoted generally does include the earth.
 
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The codes that are usually associated with the cable, what do they represent as it doesnt seem to be a reseller's product code e.g. 6242Y?
Why is it that flex cable includes the earth and installation cable does not?
 
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Why is it that flex cable includes the earth and installation cable does not?

Flex cable many or may not have a green/yellow conductor

Probably because it is a given that installation cables must have an earth cable as part of the regulations requiring an Earthed conductor being present at all installed fittings.

Items such as a double insulated table lamp are not installed and may not require an Earth
 
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There is no such thing as “13amp cable”

1.5mm cable may be capable of carrying 13amps, in an ideal situation.
Put 1.5mm cable through 2ft thickness of loft insulation and you may have an overheat situation if you draw 13A.
 
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Why is it that flex cable includes the earth and installation cable does not?

A 'core' typically means an insulated copper conductor.

So called 'installation cable' always has a bare copper earth conductor, so is referred to as 2 core and earth, three core and earth, etc etc.

Flex doesn't have a bare earth conductor - if it has a green and yellow core, this core is counted in the description.
 
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Flex is normally designed to be used where it can be seen, and as such it does have a amp rating as under normal conditions it will not be covered in any way. And it is designed to flex hence the name, it has many strands of thin wire, when installation cable is designed to be fixed, so has less strands in each core, and once installed should not be subject to much movement, and since it may be covered will not have a fixed amp rating, you need to look it up.

I would not expect the wiring to thermostats to move, so does not need to be flex, and I would expect flex marked as 13A to be 1.25 mm² there is nothing wrong using flex instead of the stiffer twin and earth, in fact items like caravans have to be wired in flex as the chassis and body can flex so the cable has to flex with it, main reason for not using flex is it costs more.

With hydraulic UFH the cable to the thermostat does not carry much current, however with electric it often does, and it depends on the cold junction as to if the cable used actually gets warm during use, cable in general comes in three temperature levels 60°C, 70°C and 90°C flex is often rated at 60°C with so many variables no one can say yes or no as we don't know route or how close to the heating mat.

Some one needs to sign that they have designed, that person should select the cable to use.
 
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ericmark,
So if the more rigid grey lighting 1.5mm 3 core and earth cable can be used instead of flex, then I might as well save on the cost. Is it possible to get different coloured 1.5mm cable just so that it is not confused with mains cable if in the future it something needs to be opened up?

My UFH is wet rather than electric.
 
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Is it possible to get different coloured 1.5mm cable just so that it is not confused with mains cable if in the future it something needs to be opened up?
No.

And if anybody is "opening things up" without knowing what they are opening up they should not be opening it up.
 
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Is it possible to get different coloured 1.5mm cable just so that it is not confused with mains cable if in the future it something needs to be opened up?
Should it be blue as its related to your wet underfloor heating? Do you think it might get full of water?:rolleyes:

Lets have redish cable for ovens that get warm, green cable for power that goes into the garden......
 
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ericmark,
So if the more rigid grey lighting 1.5mm 3 core and earth cable can be used instead of flex, then I might as well save on the cost. Is it possible to get different coloured 1.5mm cable just so that it is not confused with mains cable if in the future it something needs to be opened up?

You used to be able to get it in white or grey. But since the cores changed to blue/brown the white has disappeared.
 
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