Saddle / Fixing Spacings

[Patryk]

Hello guys. This is my first post so go easy on me.

I have had a install job at the company I work for currently. It is pvc 20mm conduit run on the wall horizontally. Seeing that the 18th edition in reg (521.10.202) Note 3 says that plastic clips are not meant to be used as a sole means of support and suitably spaced metal fixings should be used. So for the sake of this argument and this installation, we are using all metal saddles. My confusion begins that according to my supervisor the saddles are meant to be spaced at 250mm apart and no more then 150mm from a bend. I referenced back to the onsite guide Appendix D, Table D3 which says that distance between supports (metal saddles) for 20mm Rigid Insulating (PVC) should be be no more then 1.5m Horizontally and 1.75m vertically. Note B mentions clips should be no further then 300mm from a bend.

I have heard from various sources that the spacing should be 250mm between the saddles. My question is, am I right to think that the spacings they are using is unnecessary or are they correct. If so, what regulation specifically says this and/ or what table shows this. I really want to do my work correct but I also want to be able to reference it back and understand it.

Thanks in advance guys

 

[Ian1981]

Hello guys. This is my first post so go easy on me.

I have had a install job at the company I work for currently. It is pvc 20mm conduit run on the wall horizontally. Seeing that the 18th edition in reg (521.10.202) Note 3 says that plastic clips are not meant to be used as a sole means of support and suitably spaced metal fixings should be used. So for the sake of this argument and this installation, we are using all metal saddles. My confusion begins that according to my supervisor the saddles are meant to be spaced at 250mm apart and no more then 150mm from a bend. I referenced back to the onsite guide Appendix D, Table D3 which says that distance between supports (metal saddles) for 20mm Rigid Insulating (PVC) should be be no more then 1.5m Horizontally and 1.75m vertically. Note B mentions clips should be no further then 300mm from a bend.

I have heard from various sources that the spacing should be 250mm between the saddles. My question is, am I right to think that the spacings they are using is unnecessary or are they correct. If so, what regulation specifically says this and/ or what table shows this. I really want to do my work correct but I also want to be able to reference it back and understand it.

Thanks in advance guys

There’s guides for each spacing but ultimately I’d go with the manufacturers recommendations.

 

[davesparks]

250mm sounds ridiculously close to my mind.
On the rare occasions I use plastic conduit I've always worked to 1m spacings,

 

[Dave OCD]

I tend to go for around 600mm vertically and a bit less horizontally with 20 and 25mm pvc but that's just me. 250mm is ridiculous though !

 

[JeanGenie]

Sounds to me like they're getting the distances confused with flexible conduit (copex). 250mm spacings on plastic would look stupid.

 

[westward10]

Is this inside or outside.

 

[Patryk]

Is this inside or outside.

This is ran outside but over a roofed wall so direct contact with rain wont be an issue, running at a height of 2m. This is also a communal area for 2 flats. Regarding what the circuit is for.... it is meant to provide emergency lighting to the emergency escapes of both flats and to the emergency outside staircase. It also provides emergency lighting to an outside corridor with a roof that leads around the front of the house. PVC is not ideal and I do realise as it expands and contracts under hot/ cold conditions but this is what has been requested.

 

[westward10]

I would be more liberal with the fixings if it is external as the temperature fluctuations can cause the tube to deform if slip joints are not employed.

 

[ruston]

I would be more liberal with the fixings if it is external as the temperature fluctuations can cause the tube to deform if slip joints are not employed.

It looks awful too, common on south facing walls.

 

[Andy78]

Agree with more frequent spacings outside for PVC.

No-one likes a droopy tube

 

[westward10]

It looks awful too, common on south facing walls.

Funnily enough was on a job recently where the tubes had totally sagged and pulled out of their connections. They were actually bent into shape and couldn't be refitted.

 

[Dustydazzler]

I do 300mm (one hammer length) for external plastic tube , it helps prevent dandy droopy conduit

Inside I would just do what ever the OSG states