Cable factors in trunking, conductors over 25mm^2.

[chrislee765]

Hi All,

I have been searching the forum but can't find this anywhere. Can you please see if my interpretation of this is correct:

50x50 trunking, 2m run with 1 90[SUP]o[/SUP] bend.
4 x 50mm conductors,
1 x 35mm conductor.

As there are no factors for over 25mm[SUP]2[/SUP] I have to work it out manually

50x50 = 2500mm[SUP]2[/SUP] (total space)
-
4x50 = 200mm[SUP]2[/SUP]
1x35 = 35mm[SUP]2[/SUP]
Total 235mm[SUP]2[/SUP] which is less than 45% of the trunking capacity, therefore 50x50 is compliant?

Thanks for your help,
(this is my first post )

 

[jc_150]

Hi Chris
I am using IET On Site Guide green book for reference and as you already know Table E5 goes up to cable size 25 mm sq. and Table E6 is for the trunking sizes. However the rest of the page under table E6 states what to do for cable sizes not tabulated in TableE5 (too long to type out here). It seems you are calculating correctly provided you are using the internal csa of the trunking, and keeping to 45% space factor, and assuming you are not breaking any rules for minimum internal bend radius ( Table D5) And as this is your first post, this is my first reply. Have fun
John

 

[plugsandsparks]

two things spring to mind, one is insulation, and the other is how to get them around the 90 degree bend. Some cables are better than others for this and some go to 90C which can help if you are having some issues with load.

 

[Dcf]

i take it the op is for some design project or something?
cos in real life the 50mm tails will be hanging out of the 90 degree bend by some distance.

 

[MarkieSparkie]

Hi All,

I have been searching the forum but can't find this anywhere. Can you please see if my interpretation of this is correct:

50x50 trunking, 2m run with 1 90[SUP]o[/SUP] bend.
4 x 50mm conductors,
1 x 35mm conductor.

As there are no factors for over 25mm[SUP]2[/SUP] I have to work it out manually

50x50 = 2500mm[SUP]2[/SUP] (total space)
-
4x50 = 200mm[SUP]2[/SUP]
1x35 = 35mm[SUP]2[/SUP]
Total 235mm[SUP]2[/SUP] which is less than 45% of the trunking capacity, therefore 50x50 is compliant?

Thanks for your help,
(this is my first post )

From my Trunking and Cable Data:
Trunking Factor for 50 x 50 One Bend = 1037
Cable Factor for 35mm[SUP]2[/SUP] = 95
Cable Factor for 50mm[SUP]2[/SUP] = 132.7

(4 x 50mm[SUP]2[/SUP]) + (35mm[SUP]2[/SUP])= a Combined Cable Factor of 548.8 + 95 = 643.8 which is less than the Trunking Capacity of 1037 and so complies.

 

[johnboy6083]

can you post a link to the data you have please markie sparkie?

 

[chrislee765]

Thanks all for your replies.

Yeah it's for a design project but I hadn't taken into consideration whether the conductors would fit in the bend. My naivety of the physical size of the cable assumed it would.
MarkieSparkie I would too be interested to find out the source of your cable factors please?