twin and earth protection

[Baker1988]

Hi every one I am doing some drawing of different types of cables and labeling all the constructional parts I am just a bit confused on twin and cpc is the insulation around the actual conducor classed as basic protection and the out sheath based as mechanical protection or fault protection or am I wrong just not sure its be a about 2 years since I last did this

 

[rantoftheday]

Outer sheath is basic protection. Conduit, capping or the like is mechanical protection and the cpc is there for fault protection

 

[Baker1988]

Ahh I new it was something like that thank you

 

[Risteard]

The sheath is only for mechanical protection. That is why it is described as insulated and sheathed cable. The sheath is mechanical protection and does not meet the standard for insulation.

 

[Baker1988]

The sheath is only for mechanical protection. That is why it is described as insulated and sheathed cable. The sheath is mechanical protection and does not meet the standard for insulation.

so the outer sheath (gray bit) is there for mechanical protection

 

[Darkwood]

To be correct the outer sheath is environmental protection which has several sub sections one of which is its mechanical protection... T&E sheath has a very low mechanical protective property and is amongst other things a chemical, water, uv etc etc barrier although its resistance in some of these areas may be very low (standard grey T&E has low UV protection)....

It is wrong to say the outer sheath is for mechanical protection as this give the miseading idea it is its sole purpose, also confusion can arise to newbies thinking that it affords mechanical protection with regards to buried cables <50mm if you state the outer sheath gives mechanical protection...

Although it does to a minimal degree it should always be said to provide environmental protection then its not sending out the wrong message.

 

[Baker1988]

To be correct the outer sheath is environmental protection which has several sub sections one of which is its mechanical protection... T&E sheath has a very low mechanical protective property and is amongst other things a chemical, water, uv etc etc barrier although its resistance in some of these areas may be very low (standard grey T&E has low UV protection)....

It is wrong to say the outer sheath is for mechanical protection as this give the miseading idea it is its sole purpose, also confusion can arise to newbies thinking that it affords mechanical protection with regards to buried cables <50mm if you state the outer sheath gives mechanical protection...

Although it does to a minimal degree it should always be said to provide environmental protection then its not sending out the wrong message.

O ok then I understand so what is the pvc arou d the conductors classed as is it basic protection

 

[Darkwood]

The inner pvc around the copper is Insulation protecting against the voltage present (Dielectric strength)in the cable and on its own wont be suitable for alot of environments hence the need to be housed in conduit or trunking etc mostly because its mechanical protective properties are very low and requires additional even in the most basic install..

Check out appendix 5 .... this breaks down the external influences that cables are design for .... if you ever use FP200 specifically the older stuff the outer sheath was quite stiff but the inner insulation was very easily damaged as it could be split by simply pulling at it with your fingers.... this is mainly because its designed to withstand high temp's and the available materials at the time had downfalls which modern fp cables have managed to improve on while still affording similar protective qualities.

Be careful here im giving advice on what it actually is and does and you should use the terminology your college taught you if any ... i learnt this 25yrs ago

 

[martinh287]

Inner insulation provides basic protection.
Outer sheath like said offers mechanical protection although I do like the wording of environmental protection. As like said it does offer little mechanical protection

 

[Darkwood]

Ill just add im answering with regards to Twin pvc cables here and in the case of singles it would be classed as both insulation and environmental protection but even saying this the outer sheath of Pvc/Pvc does have its own dielectric strength that usally meets the purpose of the voltage its handled with but it is not there for its insulating values but as a protection of the inner insulation ...its insulation properties are similar if t the same normally as a back-up a double up for safety.

 

[Darkwood]

If colleges are teaching that the outer sheaths are there for mechanical protection then im not supprised this question keeps rearing its head its there for environmental protection of which mechanical is a category ... it also provides some UV protection but very little ...... now if you said its there for UV protection it misguides you to assume it can be used in direct sunlight where in fact it would degrade very quickly if done.

Hope you can see why it should not be expressed as been present for mechanical protection without explaining its level of protection and that is only part of the protection it provides

 

[KAS1]

Out sheath of T&E for mechanical protection whatever next...........................

- - - Updated - - -

outer......................

 

[Darkwood]

To put it concisely the outer sheath offers Mechanical Protection as well as other properties.. it is wrong to express it as - 'it is there FOR mechanical protection'

 

[GLENNSPARK]

Outer sheath is basic protection. Conduit, capping or the like is mechanical protection and the cpc is there for fault protection

no...Look in definitions

no it isn`t.

 

[Guest55]

no...Look in definitions

no it isn`t.

did you get some coloured crayons for xmas ?
lol ;-)