There are not many, if any advantages to installing the circuit as a ring on a 16A breaker. The only advantage I can imagine is if you should ever require more power up there with a ring main you can change the breaker to 32A (subject to testing).
A ring main can serve an area up to 100m² and a 20A/16A radial up to 50m².
If you can safely say you will never need that much power up there, either a 16A or 20A radial will be fine. A 2.5mm² in a conduit in a plaster gives it method 3. 2.5mm² method 3 has a rating of 23A. Ambient temp correction for 35deg derates cable to 21.62A, hence as long as the volt drop is less than 4% (@20A) and efli test is adequate for a 0.4s disconnection, then a 20A radial will be fine.
A ring main can serve an area up to 100m² and a 20A/16A radial up to 50m².
If you can safely say you will never need that much power up there, either a 16A or 20A radial will be fine. A 2.5mm² in a conduit in a plaster gives it method 3. 2.5mm² method 3 has a rating of 23A. Ambient temp correction for 35deg derates cable to 21.62A, hence as long as the volt drop is less than 4% (@20A) and efli test is adequate for a 0.4s disconnection, then a 20A radial will be fine.
