Saving Money - 3 Phase Switchgear

That doesn't sound right, perhaps your friend has made some other changes (or something has changed recently) that could result in these perceived changes.

Change of seasons perhaps?

maybe yes and maybe no...no matter what phase it is you will still have the same power consumption due to loads operates at their rated power...

Not on the basis of what we have heard so far; instead, he has only spent some money.

If he has multiple large single phase sub-panels feeding a variety of separate buildings, he might be saving a little on the initial cost of the main switchgear. But otherwise, no.

There is a common "old wives tale" that says that 3 phase is more efficient than single phase. Even if it were true (and it is not), he would have had to change his motors to 3 phase as well, and he apparently didn't. It's a moot point either way though, there is no significant difference in the efficiency of modern motors between 3 phase and single phase. If you are worried about it, you can shop around and find high efficiency motors in either format.

PS: Another possible savings may have been that he bought used or surplus 3 phase gear for a song, compared to buying new 1 phase gear. But that would not be directly related to it being 3 phase.

This scenario is actually pretty common for zoned heating & cooling. The area to be climate-controlled is separated into several zones (usually one or 2 rooms with possibly a corridor), and each zone is served by a separate A/C unit and air handler. Rooms not in use are either not cooled at all or the temperature setting is much higher (say 80F) than for rooms in use. In the winter heating works the same way.

For small air conditioning loads a single phase unit is less expensive than a 3-phase one. He's saving money on the air conditioning equipment, the wire to each unit (2 wires vs. 3) and on the single phase disconnects at each unit. But the biggest savings is on his utility bill, because he's only heating/cooling the areas which need it. Our utility advises new construction customers to consider zoned climate control in their building design for improved energy efficiency.

It IS possible that the utility has a "better" rate for power with 3-phase.

If he is buying 3-phase power, then splitting it into 3 separate 1-phase loads (hopefully reasonably balanced) then he MAY be buying his power cheaper due solely to the utility's rate structure.

Most of us know that he is using the same amount of power, no matter what the phase of the service or loads.

It will depends the power factor controller install in the switchgear, usually a 3 phase PFC switchgear use the controller sampling the PF through one phase, this is used in a balance load grid, but you said his use a single phase panel, so I am a little confused. This type is for independent phase compensation, it can use in the situation you said.

maybe it will help you

if after your observations you have noted that your friend has single phase switchgear, that would suggest that the A/C is single phase, unless he has 3 single phase breakers attached to the A/C unit... clarity on this point would help.

Many commercial properties have 3 phase supplies, divided into single phase supplies to lights, power outlets, etc, etc.... all connected to single phase breakers/switchgear, which are in turn connected to the main incoming 3 phase supply.

However, doing that the goal is then to balance the total power demand over the 3 phases, that is, so many light on each phase, so many power outlets attached to each phase, then that goal is achieved.

So your friend has a single phase disconnect on his A/C.. not sure of what your problem is.. and need more info on how he can make the claim he's saving money.

Point of caution.. if he does have a 3ph A/C unit and is using 3 single phase disconnects, then in the UK that would be illegal as it would be defined as 3 SEPARATE points of isolation, and not one.

A 3-pole breaker can be used as a dbl pole and a sgl pole breaker or as 3 sgl pole breakers. Each pole is independent of each other, but throw all at the same time. Basically a 3P3T switch. I don't know what a 3-pole breaker sells for?

Hi there

Your friend runs single phase on three phase equipment....may be the equipment is running very slow, thats why his saving money??

cheers