conduit sizing question

[Adie moore]

I'm using some conduit on a job and I feel like I'm going round in circles. when deciding what size conduit is required I can't find anything in the byb, just things similar to the link below. and am I right in thinking this is purely a guide as to what can be pulled in easily? the only other consideration I can think of is grouping factors (table 4c1). am I missing anything?

cheers adie

http://www.eyreandelliston.co.uk/pdfs/tech_4.pdf

 

[cliffed]

Really only 2 sizes to choose from,20mm & 25mm if anything bigger needed then metal trunking.

 

[Ian1981]

Have a look in the on site guide.
Gives you the cable factors for singles and the overall conduit factor

 

[soms]

I'm using some conduit on a job and I feel like I'm going round in circles. when deciding what size conduit is required I can't find anything in the byb, just things similar to the link below. and am I right in thinking this is purely a guide as to what can be pulled in easily? the only other consideration I can think of is grouping factors (table 4c1). am I missing anything?

cheers adie

https://www.google.co.uk/url?sa=t&s...ghnMAU&usg=AFQjCNG1wMqAHAibd4EwYONqtCLnHModzw

This appears to be a reproduction of the tables from The On Site Guide, Appendix E.
At the start of this appendix it is stated that this is guidance, which takes into account the ease of drawing-in single-core PVC insulated cables but not the electrical effects of grouping.

 

[Pete999]

I'm using some conduit on a job and I feel like I'm going round in circles. when deciding what size conduit is required I can't find anything in the byb, just things similar to the link below. and am I right in thinking this is purely a guide as to what can be pulled in easily? the only other consideration I can think of is grouping factors (table 4c1). am I missing anything?

cheers adie

https://www.google.co.uk/url?sa=t&s...ghnMAU&usg=AFQjCNG1wMqAHAibd4EwYONqtCLnHModzw

16mm 3mm what about these two?

 

[Squid]

Really only 2 sizes to choose from,20mm & 25mm if anything bigger needed then metal trunking.

Do they still make 32mm?

 

[Pete999]

Do they still make 32mm?

Still in the sizing data in BYB so I would assume so. Only used rarely a right syd to work with.

 

[Squid]

Still in the sizing data in BYB so I would assume so. Only used rarely a right syd to work with.

Tell me about it as a scrawny 22 year old I had to fit out a plant room on the roof of a building on London Wall, I bounced and bounced until I robbed a short length of scaffold pole to make life easier, threading it though..........

 

[Pete999]

Tell me about it as a scrawny 22 year old I had to fit out a plant room on the roof of a building on London Wall, I bounced and bounced until I robbed a short length of scaffold pole to make life easier, threading it though..........

Even worse than bending it.

 

[Marvo]

I'm guessing the table you've highlighted would allow for a 40 or 50% air gap in the conduit which is critical for cooling. If you overfill the conduit then the current carrying capacity of the wires would be less than the figures given in the regs for the conduit installation method and you should derate accordingly.

 

[Ian1981]

You shouldn't be over filling the conduit in any event as for example a 4 meter length of 20mm conduit has a factor of 286 straight so your cables installed in the conduit and adding the total factors for individual cables shouldn't go over 286.

A single stranded 1.5mm conductor for example has a factor of 22 were the length of conduit exceeds 3 meters and a factor of 31 were it doesn't exceed 3 meters in length

 

[freddo]

Do they still make 32mm?

You can also buy 1 1/2" and 2" conduit.
Barton Conduit and Fittings | Hub Le Bas - http://www.hublebas.co.uk/products/product-overview.aspx?pid=76e1d76e-e67d-438f-a490-7fd1d6edaadd