In no particular order ...
Not sure if this has been explicitly stated before, or if you'd twigged, but for your purposes you can largely think of the 3 phase supply in terms of 3off single phase supplies. For premises with a single phase supply, all that happens is that the DNO picks one phase and feeds that in from the street - feeding different premises from different phases so the loads get balanced.
There is 415V between circuits on different phases, but that's not usually a practical consideration*.
For the quantity of services you are looking at, you will may be looking at it being done in trunking (or cable tray if it's hidden) and conduit. Adding additional circuits is relatively easy later on if everything is surface mounted - it does become more of an issue if you want concealed wiring which would require chasing out for solid walls. Rather than having trunking at a high level and lots of conduits dropping down the walls, it may (depending on your layout) be worth considering dado trunking so you'd just have the outlets (whether "industrial" sockets, 13A sockets, or wired connection plates) on the trunking or just below it.
Multi compartment trunking would then give you somewhere to run other cabling (data, av etc).
Looking back a few posts, I'm thinking again about those dedicated 10A supplies for the treadmills. It's hard to see why they need dedicated supplies other than the manufacturer doing a CYA exercise. 8A startup isn't a problem, and 3-4A running is definitely not a problem for several machines running on one 32A circuit (either ring on 2.5mm cable or radial on 4mm cable) with either 13A sockets or fused spurs (FCU, Fused Connection Unit). 6 units on one circuit is only 18-24A, and 8A for starting shouldn't be a problem - again, as long as you don't have a number of users carefully synchronising their starts. it's hard to see why 4 should not be OK under pretty well any circumstances. That cuts down the number of circuits down somewhat - from a planned 20 to perhaps only 4 or 5, with a commensurate reduction in cost.
I think an FCU per machine would count as a dedicated supply. And if you think about it, once you get back to your main distribution board, then all the supplies come together anyway !
Now, as to doing some of the work yourself. You need to find your lecky and discuss the project with him first. Many will be happy for you to act as labourer - provided they think you will be a help rather than a hindrance. What they are likely to take a very dim view of is coming to a job to find it's half done without any prior discussion, and they are expected to sign it off.
If chasing is required, then I think you'll find there's no objection whatsoever to you doing that yourself - but discuss things first.
* It may be if lighting is split across phases - then there may be 415V between wires in the back of the switch, but that's really only of concern to (hopefully) competent electricians who should be aware of this risk.
Not sure if this has been explicitly stated before, or if you'd twigged, but for your purposes you can largely think of the 3 phase supply in terms of 3off single phase supplies. For premises with a single phase supply, all that happens is that the DNO picks one phase and feeds that in from the street - feeding different premises from different phases so the loads get balanced.
There is 415V between circuits on different phases, but that's not usually a practical consideration*.
For the quantity of services you are looking at, you will may be looking at it being done in trunking (or cable tray if it's hidden) and conduit. Adding additional circuits is relatively easy later on if everything is surface mounted - it does become more of an issue if you want concealed wiring which would require chasing out for solid walls. Rather than having trunking at a high level and lots of conduits dropping down the walls, it may (depending on your layout) be worth considering dado trunking so you'd just have the outlets (whether "industrial" sockets, 13A sockets, or wired connection plates) on the trunking or just below it.
Multi compartment trunking would then give you somewhere to run other cabling (data, av etc).
Looking back a few posts, I'm thinking again about those dedicated 10A supplies for the treadmills. It's hard to see why they need dedicated supplies other than the manufacturer doing a CYA exercise. 8A startup isn't a problem, and 3-4A running is definitely not a problem for several machines running on one 32A circuit (either ring on 2.5mm cable or radial on 4mm cable) with either 13A sockets or fused spurs (FCU, Fused Connection Unit). 6 units on one circuit is only 18-24A, and 8A for starting shouldn't be a problem - again, as long as you don't have a number of users carefully synchronising their starts. it's hard to see why 4 should not be OK under pretty well any circumstances. That cuts down the number of circuits down somewhat - from a planned 20 to perhaps only 4 or 5, with a commensurate reduction in cost.
I think an FCU per machine would count as a dedicated supply. And if you think about it, once you get back to your main distribution board, then all the supplies come together anyway !
Now, as to doing some of the work yourself. You need to find your lecky and discuss the project with him first. Many will be happy for you to act as labourer - provided they think you will be a help rather than a hindrance. What they are likely to take a very dim view of is coming to a job to find it's half done without any prior discussion, and they are expected to sign it off.
If chasing is required, then I think you'll find there's no objection whatsoever to you doing that yourself - but discuss things first.
* It may be if lighting is split across phases - then there may be 415V between wires in the back of the switch, but that's really only of concern to (hopefully) competent electricians who should be aware of this risk.
