Trunking and Steel wired armour cable

[L Plate]

Hello and good evening all !!

Before anything else i would like to say " HAPPY NEW YEAR TO ALL "

I am on my practical task concerning TRUNKING AND STEEL ARMOUR CABLE I do understand some of the questions but am not really sure if this is right ..

1) describe when steel trunking is normally used, with its advantage and limitations.

Answer : In domestic and commercial ? ( hospitals, hotels , garrage etc. )

: the advantage of this is for the future use, if incase you need to add or run new cables... while the limitation is , you cant overload the trunking because more cables will creat heat ?? PrayPray

2) State the precaution you must take when using galvanised steel trunking.

Answer : be very carefull on not to damage any cable that might cause short circuit and make sure there is no sharp bends or sides , this might cut or damage the cable shealth ??? Pray

3) describe the rules in respect of the numbers of cables allowed in steel trunking and the reason why this is used ?

Answer : as far as OSG says , sizes and types of cable or trunking other than those given in tables 5E and 5F ( OSG appendix 5 ) the number of cables installed should be such that the resulting space factor does not exceed 45% of the net internal cross-section area ??

4) how to ensure that the steel trunking is correctly "earthed " and where would you use the earthing rings??

Answer: Can i pass this one please ?Pray ( i will try , screw an earth cable into the trunking and connect it to the water pipe ??? headbangheadbang

5) Describe the spacing method of support stated in the OSG in respect of the steel wired armour cable .

Answer : Pass< can anyone please tell me where to find this in the OSG

6) give examples of why , when and where cable tray be used ?

Answer : Industrial ? this is used to support those big armoured cables.

7) how is the tray normally "earthed" to the steel trunking and describe a method of testing whether the tray is earthed correctly>

Answer : Pass to this question >>> Can anyone help me please Pray

( 7) You would normally use earthing straps to bond trunking or conduit....

shared by Andy )

thanks again guys for your help..

have a nice evening to all

 

[Zeespark]

7) You would normally use earthing straps to bond trunking or conduit.

AndyGuinness

 

[the doctor]

hi

that bonding straps thing is questionable.

i remember being on the arndale centre(got blew up by terrorists in 1996) on

nights re-wiring back of shop extract fans.....the install was conduit /trunking with no earth and no silly straps.....

i said to my mate" this is futile" and loop impedance tested a circuit one night before rewiring, we got 0.1ohms. we then spent all night re-wiring with a nice new equal size cpc. last job of the night was to test. guess what we got.....

0.1ohms

"see" i said, "told you"headbang... so i remain to be convinced....

 

[Zeespark]

Doc I would always use a seperate CPC with the straps as back up, never rely on them soley. I apologise if I have caused a mix up.

AndyGuinness

 

[the doctor]

no zeespark, not at all,

i am just questioning how we used to install with no cpc at all, then cpc and now, today cpc and straps/ curly leads etc....it just makes me wonder

 

[Zeespark]

Just suppose its the aim to make everything as intrinsically safe as possible now, much cant be a bad thing, and you do it to the best of your ability.

AndyGuinness

 

[L Plate]

hello guys ,

thanks for your reply to my thread,

I would assume ( since no one tell me its wrong ) that my answers are correct or close to the right answer??

thanks again for your help