Electrical service/build-out leased space

[curriergroh]

I need some electrical info. Maybe someone can illuminate.

I'm currently working with the landlord of my space to get the electrical wired. The space doesn't have anything right now. The building has 3 phase 4 wire 120/208 service.

I will have a cnc mill using 3 phase, woodworking equipment, and computers. So it would be ideal to have 120, 240, and 3 phase service int he space.

Here is what the landlord is offering/suggesting and I need to know if it is possible/good idea:

He will run 3 phase from an existing breaker box to a breaker box in my space. He wants us to purchase a 3 phase watt meter to put inline in between the two breaker boxes to measure our usage. He bought a 3 phase box and put in breakers for 3 phase, 240, and 120. Then I would pay for surface mounting conduit and outlets where I need them.

Can 3 phase be run from one box to another?

Can a 3 phase meter be used to measure usage when the box in our space will be using 3 phase, 240, and 120?

What don't I know that I should know about this?


I have contacted some electricians to see if they can consult on the landlords end, he will use an in-house guy that is not licensed. Then the electrician could do the rest of the work for me.

[Geof]

Al the Man is the one for a definitive answer but what you are describing is the way my building is wired. Three phase 120/208 is pretty much the standard up here.

Because you have 208 not 240 you should check that your motors can run on 208. Most can but if you have older motors you may have a small problem with reduced power and overheating.

You don't mention amperage. What size breaker and wire is the Landlord using to supply your space? A 60 amp supply would probably be adequate but 100 amp would give you the capacity for getting more machines. Less than 60 amps may give you problems with the starting surge on motors tripping the breaker on the Landlord's side.

[Al_The_Man]

As Geof suggests, I would look at the 3ph issue first and see what you can run on 208 3ph.
Some machines have an internal transformer with adjustable taps.
If you can get away with using the 208, then that leaves 120/240, you already have the 120v.
See what single phase loads are critical on 208 instead of 240v 1ph, how many do you have at 240?
If the 240v loads are not that high then a 208/240v 1ph transformer may be a possibility.
It all comes down to your power demand for any particular voltages.
The landlords way is viable, but I would also opt for the 100a service while you are at it if you go that route.
Al.

[curriergroh]

The box he is going to mount in the space is 100A. Is the box the relevant item or is it at the other box where he is going to source ours from that matters?

I am waiting to buy a Hitachi X200 vfd (X200-022NFU) until the power is sorted. That will be paired with a Keling 2.2kw spindle that is already purchased. The spec sheet for the spindle says 220v. Is the X200 going to work on 208 3 phase?

There is currently no equipment needing 240 single phase.
I am planning for 3 20A breakers for the 120 service.

Is it possible to wire the breaker box to have 120 if its source is 3 phase?
Is a transformer needed or is it just a matter of wiring inside the box?

If you need more information let me know. Thanks for the help.

[Geof]

The 100 amp rating is the maximum that may be fed into your box. What matters is the breaker rating on his side that is supplying your box.

Yes you can get 120 from 208 three phase. You get 208 single phase between any two lines of the three phase supply and 120 single phase between any line and the neutral.

[curriergroh]

He is planning on using a 150A breaker on his end and our box is rated for 100A. Is that a problem?

I have contacted an electrician to come out and check things after the landlord has done his bit.

[Al_The_Man]

As long as there is current protection in the box your end for 100A, especially if it is going to be wired for this capacity.
Although the conductor size from his 150a to the 100A should be capable of carrying 150A.
Al.