Calculation for 240V/1 or 240V/2 Phase system

[electricalintern]

This is my first time seeing a 240V/2 Phase breaker.

The utility company said they can provide the store with 400 amp with (2) 100:5 CT.

Does that mean the store will get (2) 200 AMP 240V/1 Phase or 400 AMP 240V/2 Phase?

I know 1 Phase has 3 wires and 2 Phase has 5 wires, but how would you add all the loads up to make sure the circuit is not overloaded.

 

[don_resqcapt19]

2 phase is very rare and it is very unlikely you will be getting a new 2 phase service.

A 2 pole 200 amp breaker at 240 volts will support 48kVA of load. You will have to do a load calculation per Article 220 to determine the load.

 

[infinity]

To echo what Don stated forget about 2 phase in any new construction. Since they're providing two CTs you have single phase.

 

[electricalintern]

To echo what Don stated forget about 2 phase in any new construction. Since they're providing two CTs you have single phase.

How many CT will they provide if the service is 240V/2 Phase?

Here is an example of the what 1 Phase and 2 Phase is available at the store

My load is around 150kva but the utility company is not providing the store with 3 Phase service.

So I was wondering what my options are with 240V/2 Phase if it will get me more power at 400 AMP.

But I don't know how to calculate the 150kva to 2 Phase.

I know for 3 Phase you do sqrt 3 = 1.73

 

[don_resqcapt19]

What utility is still providing 2-phase, 5 wire services?

 

[zbang]

Peco, or whatever they're called now- center city Philadelphia (and hartford CT?) are about the only places that have it.

From Peco's Metering requirements doc (2022)-

8.9.1 Two-Phase (Maintenance Only - Not for New Construction)
Obsolete equipment in Figures 8.09 and 8.10 were removed from this Revision. For
maintenance only applications acceptable equipment is listed in Figure 8.15

 

[JoeStillman]

How many CT will they provide if the service is 240V/2 Phase?

Here is an example of the what 1 Phase and 2 Phase is available at the store

My load is around 150kva but the utility company is not providing the store with 3 Phase service.

So I was wondering what my options are with 240V/2 Phase if it will get me more power at 400 AMP.

But I don't know how to calculate the 150kva to 2 Phase.

I know for 3 Phase you do sqrt 3 = 1.73





View attachment 2569339

That sure looks like the PECO S&M form. I don't think they will give you a new 2Ø, 5W service - only upgrades like zbang said. If you do get a 2Ø service, it's a good idea to put a scott-connected transformer right after the main and feed everything with conventional 3Ø equipment.

Your 150 kVA will draw 312.5A on the two-phase side. The calculation is I = S/(2 x V) = 150,000 / (2 x 240). Here's a couple of pages from an old Electricians Handbook 9th ed. (c) 1970... (The electrician who gave it to me worked at Philadelphia Navy Yard.)

 

[petersonra]

Note that 120/208 3 phase is checked in the example. I do not think anyone will give you a new 2 phase service

You can measure 3 phase with just two cts iirc, but I think it only works on Delta systems.

I think your choice is going to be 120/240 single phase or 120/208 three phase.

From your description, it sounds to me like they are offering you 120/240 single phase 400 amps. That would be almost 100 kva. Lots of power.

However that does not match up to 100:5 cts.

 

[JoeStillman]

Is this a tenant fitout in an old building? For a 100A, 1Ø service there wouldn't even be any CT's. Just an in-line meter.