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Wheelock7002T4Ever
August 18th, 2003, 11:16 AM
Well, How DO I get both 120 & 240VAC on 3 phase? Any information would help me greatly!!

imported_Ron
August 18th, 2003, 11:35 AM
You have asked a somewhat involved question, without giving us enough information.
What is the system voltage you are dealing with? Is it 208V 3 phase or 480V 3 phase?
Generally you need to properly choose a transformer.

Wheelock7002T4Ever
August 18th, 2003, 12:24 PM
It is a 120/208 3ph 4 wire 100amp subpanel. I need 240volts & 40amps for an air conditioning condenser.

imported_Ron
August 18th, 2003, 12:45 PM
Unfortunately your choice of AC unit is not correct. A 208V source cannot reliably operate a 240V load. If you rechoose your AC Unit, you could easily use your existing source to get both 120V and 208V single phase.

In any case, the transformer to use would be approx 5kVA. The GE product starts at 15kVA. Catalog Number : 9T23B2611G15

It is a pretty expensive solution that could be erased by re-choosing the correct AC unit.

Wheelock7002T4Ever
August 18th, 2003, 12:49 PM
On the panel, it says "Use only 240v rated breakers for 240v circuits, connecting the wildleg to neutral will feed 208v."

Wgoodrich
August 18th, 2003, 02:00 PM
If you truly have 120/208 four wire three phase wye system as a service that lable would not apply. You do not have a wild leg with a 120/208 wye connected three phase service. Are you sure you have a 120/208 wye connected three phase service with four wires being three hot and one neutral conductor as your service feeders?

Then before you go further go to your a/c unit and look at voltage rating of your a/c unit name plate. See if it is listed for use with a voltage range of 208 to 240 volts single phase.

If you have a three phase 240 volt a/c unit again check if it is rated for a range of voltage acceptable and listed on the label for use with 240 or 208 volts.

Curious

Wg

Wheelock7002T4Ever
August 18th, 2003, 02:53 PM
Sorry, I was wrong. The label says "Connect only 240v rated breakers to the wildleg phase b. Wildleg to neutral voltage is 208v." I guess I was wrong.

Wheelock7002T4Ever
August 19th, 2003, 08:18 AM
Also.... There are apartments upstairs in this building. Right now all their circuits are 120v. They want their own panels in their apartments so when a circuit trips, they can reset it them selves. I think I can tie it in with some 3ph service, but which one? The panel will be res 100amps. Do I have to order single ph for all of the panels?

Wgoodrich
August 19th, 2003, 05:25 PM
YOu have a lot to learn about three phase. First thing you need to do is call your power company. If this is an existing service to an existing apartment building then they will tell you what type three phase you have. I seriously doubt you will find a three phase with a wild leg in an apartment building. Be careful and know what you are doing. You speak of a 100 amp service to an apartment building. This would not meet Code requirements meeting the demand load of more than one apartment. I am quesitioning what you are saying. Do some research with the power company and your local inspector before you do anything. You may be getting ready to do some very hazardous things wrong.

What type occupancy do your have on the main floor. Have you met the fire ratings required for a multi- occupancy building?

Be sure and be safe

Wg

Wheelock7002T4Ever
August 20th, 2003, 07:19 AM
No, no, no, currently there is 120/208 3ph 4 wire (I dont know if it is delta or wYe). I WANT to give each apartment 100amps of flexibility. Currently the all circuits in the apartments are 120v, tied in with the building's main panel. Downstairs there is a retial store, and upstairs there is 5 apartments. The building is circa 1925. The tenants want more power for their appliances, circuits keep tripping, and I've checked for loose wires, etc in all of the outlets, and have come the the conclusion they need more power. The only other circuits run to the apartments are 1 208v 1ph for a washer & dryer. I want to allow each apartment to have 100amps for their purposes, but don't need a 240v circuit, only 120's, & 1 208. Can I install a 100amp subpanel in each apartment (3 ph)? The total ampacity for the building is 800amps. There is currently 2 400AMP main 3ph 4 wire panels, and 1 100amp subpanel running off of the 2nd main panel. The total current draw is 300amps out of 800, so 600 is available for use.

Fire ratings? Such as alarms, sprinklers? My parents just bought this building, and I was asked to help in the restoration (well bringing wiring up to code). Alarms were just installed (I helped, but I had help from an electrician, and it passed fire & electrical inspection). Sprinklers were installed along while ago, 1950's by the looks of it. I tied in an OS/Y valve tamper for supervisory & a vane waterflow tamper into the building's alarm system. The alarm system also has a city box connection. (Trust me, I am more fire alarms than I will ever be AC electrical work, thats why I know the system so well)

Also, what do you recommend? Do you think 100amps is overkill? The service is existing, from the previous owner. Would it be better for another type of 3 phase service? I want to do this correct, and up to code as not to incenerate this building!

Oh, and the air conditioning condenser IS listed for 208/240v, except 3 phase. It accepted my 208v 3ph, and it works! Thanks for the help so far! Now I can enjoy the building in 70F rather than 85F!

Wheelock7002T4Ever
August 20th, 2003, 08:28 AM
Also, I don't think I have a wildleg. All 3 legs together is 208v (216v to be exact), and any leg to another leg is 208v. Also, any leg to neutral is 120v (126 to be exact again). Could this be delta or wYe? Any information is always greatful.

Wgoodrich
August 20th, 2003, 05:47 PM
From what you discribe you have a 208/120 volt three phase service.

Next you should not guess. YOu should perform a commercial demand load calculation for the retail store. Then perform a demand load calculation for each individual apartment. Then you can make an informed decision how and how much to design your service.

The Code requires a demand load calculation done by different formulas for each type occupancy.

The Code also allows two different services single phase for the apartments and 3 phase for the retail store serving this building if so required, this may be a better choice in your design. Also I suggest that you set up the single phase service with separate meters [multi-gang meterbase] to serve each individual apartment and retail store so the occupant can pay the electric bill. This will increase your profit reliability and resale appraisal of the building if you decide to sell it. Each apartment is required by Code to have its own panel and breaker set up always available to them. Yes you may and should install the panels in each apartment. You may buy a modular meterbase unit with main breakers for each meter base. Then the panels in each apartment is a sub panel with all main breakers grouped at the meter base system. Feeder is required to be a 4 wire feeder to each sub panel carrying the equipment grounding with the feeder to each apartment sub panel from the main service outside.

Check with your inspectors to see if any fire rated division walls or ceilings are required between the two types of occupancies to avoid trouble later.

We can help you perform the commercial demand load calculation if you will provide the square feet of the commercial section and list any lights that are listed over 600 watt per light, and any fastened in place equipments and their voltage, phase, and amp rating. TEll us if any show window lighting, any plug mold and how many feet anywhere in the building, heating and a/c loads with voltage, phase, and amp rating.

Tell us the square footage, phase, voltage, phase of each heating and a/c unit serving each apartment, type range, list of any fastened in place appliances, explain type of laundry in each unit or one central laundry. provide a list mentioned for each apartement separately.

Then we can calculate what you should do with your existing service and design of that service.

Curious

Wg

Wheelock7002T4Ever
August 21st, 2003, 08:08 AM
I can tell you the loads in each apt., and the retial store. For sq.
feet I have to measure. Here are the loads in the retial store:

*NOTE: ALL 120v loads are single phase. ALL 208v loads are single unless otherwise noted at triple.*

- 20 Amp 120v circuit for outlets, powering 3 computers and desk accessories. Also powering WiFi/Network switches. Total amp draw is around 10/12amps.
- 10 Amp 120v circuit for lighting around store. Total amp draw around 5 amps.
- 20 Amp 120v circuit for outlets. (don't know total amp draw)

Loads on misc. apps.

- 10 Amp 120v. Circuit for Fire Alarm. (Around 3 Amps draw)
- 40 Amp 208v, 3ph A/C Condenser (35 Amps running, 40 at startup)
- 30 Amp 208v, 3ph A/C blower (25 Amps running, 30 at spartup)

Loads per Apartment (5):

- (1) 20 Amp 120v outlet circuits.
- (1) 30 Amp 208v, single ph for washer/dryer.
- (1) 10 Amp 120v lighting circuits. (About 2 Amps per ckt. at any given time, 8 Amps at full useage)

Proposed Loads for an invidual apt.:

Note: 100 Amp subpanel installed in each apt.

- (2) 120v. 20 Amp Outlet Ckts.
- (1) 208v. 30 Amp W/D Ckt.
- (1) 120v. 15 Amp Lighting Ckts.
------------------------------------------------------------

85 Amps at peak useage per subpanel.

Additional Future Loads:

(3) 208v. 40 Amp, 3ph A/C condenser ckt.
(3) 208v. 30 Amp, 3ph A/C blower ckt.

These will run off of the main panel, not the subpanels. These A/C Units will be for the apts.


Q: Can I install 100Amp 3ph panels in each apt? I dont want to not use 600 amps of a 800amp service. Is it code to install a single ph panel in apts? Also, The W/D is listed for 208/240v, so either way they are fine.

Also, can I install res. 100Amps in each apt. pulling 2 of the 3 legs, instead of 3ph subpanels? That way I could have 208 & 120v. The apts. themselves only req. 1 phase svcs. The only 3 phase services are the A/C units, and those will run off of the main panel anyway. What I want to do is run the apts. subpanels off of the main panel. Is that allowed? I know I can use a multi-meter base, but The tenants like a fixed useage every month. That is also fine with us... It just seems easier in the short run.


Thank you for your advice and information! This is very helpful! Thanks again,

Wgoodrich
August 21st, 2003, 02:53 PM
I have been a landlord of about 22 units for approximately 25 years. Experience suggests that renters do like the utilities to be paid in the rent. However your profit may take a major loss when renters start running a bunch of baseboard heaters or open the oven door etc. and like fresh air so also leave the windows open. Why not you pay the electric !!! I advise that if you are going to do the wiring then install the separated meter system. Then you have the choice to pay their utility bills or not and the resale value of the property increases much more than the cost of the meters if installed now while you are correcting the building. An experienced landlord will most often walk away from an apartment building that is not seperately metered do to past horror stories from abuse of renters as discribed above.

We now need the square footage of each individual apartment and square footage of any community areas that may need a house panel.

Sounds like you may want to install an extra meter for a house panel for outside lighting and heating and cooling if you plan on whole house design heating and cooling. I suggest you research individual heating and cooling design per apartment.

Take if from experience the separated utilities is your best investments including heating and cooling. You are now installing it. I would redesign it all as smaller individually controlled systems controlled and paid for by the tenant whether residential of commercial tenants.

Need the square footage of each individual apartment and retail store to calculate you demand load. Also can not go by amp probe reading instead need name plate readings on fastened in place equipment only. The rest [receptacles, general lighting, laundry etc. is automatic from the information you provided already.

Curious

Wg

Wheelock7002T4Ever
August 23rd, 2003, 06:40 AM
You're probably right. I'll install the multiple meter base. But, the A/C is 3ph. And, I only want to spend money for 3 blowers & condensers. If I run the A/C off of the single ph, I will have to get 5 1ph blowers / condensers, which will be alot of money. Suggestions?

Wgoodrich
August 23rd, 2003, 08:46 PM
It is common that three phase equipment is less expensive than single phase equipment when larger motors are involved.

YOu could check into the cost of a phase convertor creating the third leg and a three phase branch circiut for each individual a/c unit.

However you are incorrect that a 3 horse power three phase cooling unit will produce more BTH than a single phase 3 horse power cooling unit. Check with some pro s to confirm this. Horse power is horse power regardless of phase input.

While it is true that a three phase hermetic motor will pull less per phase than a single phase hermetic motor. However you must remember that you have two other items to be concerned about.

One

While a 3 horse power 240 volt three phase motor will pull full load current of 9.6 amps paying for three hot wires flowing current adding in a monthly 3 phase demand sweep charge for three phase above Kw usage , the same 3 horse power 240 volt single phase motor will pull full load current of 17 amps paying for only TWO hot wires flowing current and without the monthly damand sweep charge of three phase. Single phase would be only the Kw used.

It is not true that three phase equipment is cheaper to run per month than single phase equipment. Exactly the opposite applies due to the demand sweep charge of a commercial grade electrical service. Straight single phase kw usage would equal three phase kw usage if same horse power is used.

In your case paying the higher price for the single phase 3 horse power a/c units would be the better choice. In fact it may be a better choice for a retail store if now large equipment is being used.

Just adding words for thought

Wg

Wheelock7002T4Ever
September 3rd, 2003, 07:51 AM
Each apt. is 600sq. foot total.

Thanks!

Wgoodrich
September 3rd, 2003, 08:28 PM
YOU SAID ABOUT RETAIL STORE.

*NOTE: ALL 120v loads are single phase. ALL 208v loads are single unless otherwise noted at triple.*

- 20 Amp 120v circuit for outlets, powering 3 computers and desk accessories. Also powering WiFi/Network switches. Total amp draw is around 10/12amps.
- 10 Amp 120v circuit for lighting around store. Total amp draw around 5 amps.
- 20 Amp 120v circuit for outlets. (don't know total amp draw)

Loads on misc. apps.

- 10 Amp 120v. Circuit for Fire Alarm. (Around 3 Amps draw)

REPLY;
All the above is included in general lighting per square foot calculation. The loads below would be added to the general lighitng load calculation.

YOU SAID;
- 40 Amp 208v, 3ph A/C Condenser (35 Amps running, 40 at startup)
- 30 Amp 208v, 3ph A/C blower (25 Amps running, 30 at spartup)

REPLY;
If you have no other loads and if this is a normal commercial loft building on the first floor then we need the square feet of this commercial retail store and any show windows. You will need to confirm this is a normal retail store and no further loads other than those mentioned. I need that square footage of that store before the general lighting can be calculated.


YOU SAID;
Loads per Apartment (5):

- (1) 20 Amp 120v outlet circuits.
- (1) 30 Amp 208v, single ph for washer/dryer.
- (1) 10 Amp 120v lighting circuits. (About 2 Amps per ckt. at any given time, 8 Amps at full useage)

Proposed Loads for an invidual apt.:

Note: 100 Amp subpanel installed in each apt.

- (2) 120v. 20 Amp Outlet Ckts.
- (1) 208v. 30 Amp W/D Ckt.
- (1) 120v. 15 Amp Lighting Ckts.
------------------------------------------------------------

85 Amps at peak useage per subpanel.

Additional Future Loads:

(3) 208v. 40 Amp, 3ph A/C condenser ckt.
(3) 208v. 30 Amp, 3ph A/C blower ckt.

REPLY;

Again I advise this entire building needs to be normal single phase with single phase cooling equipment as discussed in prior replies considering the type building, use and loads being used.

You said there is 5 apartments each with 600 square feet in each apartment.

A single apartment will have the following loads that must apply as you discribed the apartments.

600 square feet times 3 volt amps per square feet general lighting
equals 1800 volt amps.
1500 volt amps for laundry
3000 volt amps for kitchen
total general lighting load is 6300 volt amps.
first 3000 @ 100% then remainder @ 35% = 4155 divided by 240 volts = 17.33 amps demand load. Code requires a minimum of 100 amps per dwelling unit panel but demand load on main service serving all apartments would be 5 times 17.33 amps = 86.65 amps demand load for all apartments.

Now to this you must decided gas or electric range, furnace, dryer, water heater. If you are installing dishwasher, garbage disposal, sump pumps, or anything else not told to us that would be fastened in place appliances in each apartment. Then you must decide on a/c loads phase type and amp rating of each a/c unit. Then not in apartments we need loads of any hall way lights not in apartments and parking lot lighting these being continuous loads.

Now we got that far we need the above information to confirm demand load of each apartment. Then you need to tell us the squre footage of that retail store and if any other fastened in place loads in that retail store, if any show windows and if so liniel feet of those show windows.

You are getting there and I suspect by now you are seeing you were over wiring this building for your needs and some equipment better changed to single phase in your case.

Good luck

Wg