Hi, as part of a project for my level 3 C&G 2365 course, we need to provide power to a number of 230v single phase socket outlets on a ring final circuit for a workshop area within a building designed for light industrial work.
The considerations about current carrying capacity and other aspects are dealt with elsewhere in the project, the specific part this question relates to is conduit selection.
I am needing to calculate what diameter of conduit I would need to use to provide power to a number of metal clad socket outlets to be used in that area. Basically, I need to prove that the diameter of conduit I select would be adequate, given that, if possible, I will be looking to run 2 x 2.5mm 90 degree thermosetting cables (line and neutral) and one CPC (probably 1.5mm CSA I'm not 100% sure yet, but for the sake of getting some guidance here let's just say it's a 1.5mm CPC), and then if necessary I will run another piece of conduit back up to the trunking with the same number and type of cables, for the continuation of the ring.. OR if I could get away with it I would prefer to run both sets of 3 cables in the same piece of conduit, so 4 x 2.5mm and 2 x 1.5mm 90 degree thermosetting singles.
We are told in the brief that we must use 90 degree thermosetting non sheathed cables (i.e. singles, I'm told these are called 'tri-rated' if they are the 90 degree thermosetting type) and that the conduit must be steel. The runs would not have any bends, they would drop straight out of a steel trunking section directly down into the metal socket outlets, and would be less than 3 metres in length.
I note that the OSG appendix E gives details about how to calculate maximum number/combinations of 70 degree thermoplastic cables which can be safely run in conduit of various sizes, but I can't find any details there about thermosetting cables of 90 degree. Nor anything definitive online which contains any suggestions about conduit size limitations with regard to 90 degree thermosetting cables.
From my limited experience, I have come across conduit in 3 sizes, 20mm, 25mm and 32mm. I suppose I could just err on the side of caution and use 32mm conduit (the back boxes of the metal clad socket outlets I'm using are 47mm in depth, so I guess I could say I would hole saw 32mm holes where necessary into the back boxes to accommodate conduit adapters, and the trunking size I'm not certain of yet but given that it will be carrying a lot of cables to feed not only this ring final circuit but also quite a lot of other equipment including 3 phase equipment, I am certain it would be big enough for me to be able to terminate 32mm conduit adapters into it. But this is just based on a best guess, and I expect our tutor will require us to come up with something a bit more concrete than that.
I could ask the tutor, but to be fair I am already sending him lots of questions, and prefer to reserve contacting him for queries that I can't resolve myself/with help elsewhere, so I thought I'd ask in here in case anyone has any words of wisdom.
I have had a brief search on this site for other threads like this but can't find anything addressing this exact topic
The considerations about current carrying capacity and other aspects are dealt with elsewhere in the project, the specific part this question relates to is conduit selection.
I am needing to calculate what diameter of conduit I would need to use to provide power to a number of metal clad socket outlets to be used in that area. Basically, I need to prove that the diameter of conduit I select would be adequate, given that, if possible, I will be looking to run 2 x 2.5mm 90 degree thermosetting cables (line and neutral) and one CPC (probably 1.5mm CSA I'm not 100% sure yet, but for the sake of getting some guidance here let's just say it's a 1.5mm CPC), and then if necessary I will run another piece of conduit back up to the trunking with the same number and type of cables, for the continuation of the ring.. OR if I could get away with it I would prefer to run both sets of 3 cables in the same piece of conduit, so 4 x 2.5mm and 2 x 1.5mm 90 degree thermosetting singles.
We are told in the brief that we must use 90 degree thermosetting non sheathed cables (i.e. singles, I'm told these are called 'tri-rated' if they are the 90 degree thermosetting type) and that the conduit must be steel. The runs would not have any bends, they would drop straight out of a steel trunking section directly down into the metal socket outlets, and would be less than 3 metres in length.
I note that the OSG appendix E gives details about how to calculate maximum number/combinations of 70 degree thermoplastic cables which can be safely run in conduit of various sizes, but I can't find any details there about thermosetting cables of 90 degree. Nor anything definitive online which contains any suggestions about conduit size limitations with regard to 90 degree thermosetting cables.
From my limited experience, I have come across conduit in 3 sizes, 20mm, 25mm and 32mm. I suppose I could just err on the side of caution and use 32mm conduit (the back boxes of the metal clad socket outlets I'm using are 47mm in depth, so I guess I could say I would hole saw 32mm holes where necessary into the back boxes to accommodate conduit adapters, and the trunking size I'm not certain of yet but given that it will be carrying a lot of cables to feed not only this ring final circuit but also quite a lot of other equipment including 3 phase equipment, I am certain it would be big enough for me to be able to terminate 32mm conduit adapters into it. But this is just based on a best guess, and I expect our tutor will require us to come up with something a bit more concrete than that.
I could ask the tutor, but to be fair I am already sending him lots of questions, and prefer to reserve contacting him for queries that I can't resolve myself/with help elsewhere, so I thought I'd ask in here in case anyone has any words of wisdom.
I have had a brief search on this site for other threads like this but can't find anything addressing this exact topic
