I would think NOT choosing 3-phase would cause issues for future use.

It would mean attracting a tenant that had equipment requiring 3-phase power would be very difficult.

If I recall correctly devices are either 3-phase or single-phase.  A 2-phase supply serves only to provide single-phase redundancy and is widely used in rural settings.  For commercial premises I would think 3-phase power is essential.

A 3-phase supply won't cause any issues with use cases, and will provide more flexibility and options for your tenants:

• Those who require 3-phase equipment like electric motors
• Those who require a greater power delivery than single phase can provide (typically 63A/15kW)

For example, your tenants might might want to plug in an EV or two, and that can easily overload a single phase when you have machinery and aircon running.

You don't lose anything in going 3-phase.  Might just cost a little extra at your switchboard, and a little extra design with your electrician to ensure loads are reasonably evenly distributed over the phases.

Three phase is great.  Three phase motors are more easily controlled and can be cheaper.  Lots of commercial equipment is three phase.

Factors to consider:

- Is it likely for the tenant to have equipment that needs 3 phase power? Basically anything Industrial style. Bigger welder, largish induction motor (big pump, big compressor, metalworking machine etc).

- What will the power requirements for the site likely to be & what is the max current per phase (often 63A, sometimes 100A, for commercial/industrial you can have basically as much as you are willing to pay for, but your monthly lines charge can get very expensive). Consider likely loads - Heating / Cooling, lighting, ventilation, and Tennant stuff (Might a pizza hut suit your site? they will need 15 - 25kW for their pizza oven's, might it suit a laundromat? if so and there is no gas connection, you will need 4kW per dryer. say 10 dryers, it comes out to 40kW) Each phase provides 15kW at 63A, or 23kW at 100A.

- What is the air-con setup going to be. As an example the biggest single phase Air Con fijitsu sells is 15.5kW. Their three phase units go up to 45kW.

- What is your local lines companies fee structure. As an example vector charges the same daily & kWh fees to "general" (non-residental sub 69kW, i,.e sub 230v, 100A three phase) customers, and if you step over that amount pricing jumps and you start getting hit with capacity charges, power factor fees etc. Other lines companies charge more daily fees for three-phase customers than single phase customer's

- Has the wiring already been done. Little point getting three phase metering set up if the sparky hasn't run enough wires to actually use it.

Without knowing anything about the site (and vector or similar lines fees), my gut feeling would be to get a 100 Amp three phase supply set up. It's the max without going to more expensive lines fees, but will give you the ability to offer your space to the widest range of tenant's (a pizza place or a laundromat simply won't rent a place without enough power / gas to run their gear).

Also should give the best future proofing. There is talk about perhaps phasing out natural gas in 2050. Means tenants currently using gas (like laundromats) will be looking for spaces with a lot of electrical capacity as we approach 2050.

Also if your tenant wants to put in (AC) ev chargers, there will be better odds of having capacity to accommodate.

Downsides of three phase:

- Slightly higher capital cost

- In some area's higher daily line charges

- Can suck with solar PV setup (and battery backups) - Current inverters don't dynamically balance accross phases, so if you are generating 3kW, and it is putting 1kW to each phase while you are using 3kW, you will be charged for 2kW of import rate, and paid 2kW of the much lower export rate

OldGeek:

 

If I recall correctly devices are either 3-phase or single-phase.  A 2-phase supply serves only to provide single-phase redundancy and is widely used in rural settings.  For commercial premises I would think 3-phase power is essential.

 

Generally, two phases it is to provide more capacity.

A family house is fed by two phases, as it was too big to run off a single 63A feed, and running a second phase was the way it was done at the time (guess the lines company preferred that a single 100A or bigger feed). They wanted to provision for three phase, but in that area, it was going to be very expensive, so they didn't.

That said, we did have a number of instances, where only one phase had an outage, and were able to run an extension cord to keep the fridge going from the other phase.

[edit] - should note that things with big induction motors, pritty much need three phase, where as something like a pizza oven / sauna etc is often wired for three phase, but is just a resistance on each phase, so a sparky can bridge the three phases if there is enough capacity on a single phase service.

For a little background on 3 phase and single phase power:

Single phase power has power transmitted as a sinewave along a single conductor. There are an additional 2 cables in the cord of a three phase appliance, one for neutral (loads are connected between this and active), and one for earth (sometimes not included appliance is double insulated).

Three phase has three conductors each carrying a sinewave that is 120deg out of phase of each other. For induction motors this is great as it gives smoother power (other conductors fill in when one is at zero voltage). And it means loads can be wired phase to phase giving about 400v (cheaper welders often do this, and sometimes ignore the third phase all together). Generally the cords include 5 conductors: 3 phases + neutral + earth. (but in circumstances where the load is well balanced, the neutral can be omitted)

Single phase loads can run fine on three phase power (as long as there is a neutral wired) - Sparky will simply pick any one of the three phases, and wire between that an the neutral. Best practice is for the sparky to try and balance loads between phases, so draw on each phase will be similar. 

It would cover all use cases at 3-phase

Dulouz:

 

I've purchased a small commercial unit to lease out. We are getting meters set up and can choose single, 2 or 3 phase. If we choose 3 phase does that cause any issues for use cases?

 

commercial is always 3 phase. you would never want a commercial unit with single phase. the big question is usually how big is the supply.