3 phase service!

Status
Not open for further replies.
Doctor Electric

Doctor Electric

Member
Location
United States
My job bought an old funeral home it's freaking huge well I know how to wire it however there is a single phase service and a 3 phase service on it and the 3 phase was only doing an old air conditioning pump well 86 that we are redoing the service to bring in 400 amp 3 phase and my question is can I have the wye transformer outside maybe next to the CT and from there bring in two 200 amp lines from there and I'm prettY sure the ground is 1/0 for the service and #4 for the panels I'm familiar with three phase I just want to make sure of my transformer style and try to get the most panel space for the property it's gonna be offices with a kitchen and a workout room downstairs probably highest load appliances are gonna be.ac units furnaces hot water range 150 sub panel nothing to heavy nothing we need 3 phase for just want to utilize the power. Any takers??
 
Umm, what? :?

Your post is really hard to read with no breaks or punctuation. It bounces around a lot, I'm not entirely sure what you're asking...

Are you asking about the transformer, wire size, other?
 
Welcome to the forum. I edited your post quote to make it more readable.

Doctor Electric said:
My job bought an old funeral home it's freaking huge. I know how to wire it however there is a single phase service and a 3 phase service on it. The 3 phase was only doing an old air conditioning pump we'll 86 [sic: get rid of] that we are redoing the service to bring in 400 amp 3 phase.

My question is can I have the wye transformer outside maybe next to the CT and from there bring in two 200 amp lines from there. M'm pretty sure the ground is 1/0 for the service and #4 for the panels.

I'm familiar with three phase I just want to make sure of my transformer style and try to get the most panel space for the property. It's gonna be offices with a kitchen and a workout room downstairs, probably highest load appliances are gonna be.ac units, furnaces, hot water, range, 150 sub panel. Nothing too heavy nothing we need 3 phase for just want to utilize the power. Any takers??
Click to expand...

His question is can he run 2 200A panels from the transformer, presumably 2 sets of wires. I see no problem with that.
 
Last edited by a moderator:
Doctor Electric said:
My job bought an old funeral home it's freaking huge well I know how to wire it however there is a single phase service and a 3 phase service on it and the 3 phase was only doing an old air conditioning pump well 86 that we are redoing the service to bring in 400 amp 3 phase and my question is can I have the wye transformer outside maybe next to the CT and from there bring in two 200 amp lines from there and I'm prettY sure the ground is 1/0 for the service and #4 for the panels I'm familiar with three phase I just want to make sure of my transformer style and try to get the most panel space for the property it's gonna be offices with a kitchen and a workout room downstairs probably highest load appliances are gonna be.ac units furnaces hot water range 150 sub panel nothing to heavy nothing we need 3 phase for just want to utilize the power. Any takers??
Click to expand...

Why would you even install a transformer that will burn your own electricity around the clock with no justifiable cause?
3 phase would be great if it's going to be light industrial. Double figure tonnage AC, Shop equipment, large compressors, vehicle lift, elevators, etc like having three phase.
 
I thought that you need the transformer to get the neutral the primary is delta and the secondary is the wye transformer to get my neutral right? I'm sorry guys I'm good at what I do my job bought this place to test me and I can do the work but it's a little over my head as far as a knowledge aspect
 
Doctor Electric said:
I thought that you need the transformer to get the neutral the primary is delta and the secondary is the wye transformer to get my neutral right? I'm sorry guys I'm good at what I do my job bought this place to test me and I can do the work but it's a little over my head as far as a knowledge aspect
Click to expand...

No worries and we will be glad to help.

But I am unclear on what you are asking.

What is the electrical supply you have?

What do you want to power from it?

Take you time, explain it and hit the 'enter key' once in a while it makes it easier for us older guys to read. :)
 
If the original three phase only served the air conditioning - there is a good chance the utility supplied this from an open delta source.

If so and you transform that to a 208/120 there is a chance you overload their original high leg - as it wasn't designed to have much load on it.

Even if it was not an open delta - I think best thing is to see what it takes to get POCO to supply you with what you want instead of trying to adapt to what is there. It might not be enough capacity for the new needs anyway even if it is the correct voltage.
 
I am new to this reply or quote thing but the supply that is there is 3x 4ot legs and a regular 2ot single phase. So two total services I know how to flip the single no prob I can flip the wires and meter can for three phase

However it's on the side of the building with a drive way right past it so it's limited room for any equipment there .
I need the power for offices they are turning the funeral home into an office building so each will probably have a printer and computer stuff maybe phone chargers


none the less I need 120/240 from the service would be great because there are a number of single phase sub panels throughout the place that need re fed and changed out I guess I need to know the transformer to get the most 120/240 out of the service as I can
 
Doctor Electric said:
I am new to this reply or quote thing but the supply that is there is 3x 4ot legs and a regular 2ot single phase. So two total services I know how to flip the single no prob I can flip the wires and meter can for three phase

However it's on the side of the building with a drive way right past it so it's limited room for any equipment there .
I need the power for offices they are turning the funeral home into an office building so each will probably have a printer and computer stuff maybe phone chargers


none the less I need 120/240 from the service would be great because there are a number of single phase sub panels throughout the place that need re fed and changed out I guess I need to know the transformer to get the most 120/240 out of the service as I can
Click to expand...

I am not clear on if the transformer you speak of is customer or utility owned. It sounds like you want to just demo the existing services and just bring in a brand new three phase service. If so, you would need to set up a meeting with the utility to discuss options for the transformer location (if a padmount). Perhaps overhead or "overhead to underground" is an option as well.
 
We are demolishing the old service from the house point down to the panel the service wires I told about in the last quote were the wires coming from the street to the house are the 4 and 2 ot.

At the house with the delta power I need a neutral so I can use the service for 120/240

Idk maybe I am un clear about what I'm even doing maybe I'll just tell them to demo the 3 phase and bring in another 200 amps it might be cheaper with equipment and time also huh?
 
Doctor Electric said:
I am new to this reply or quote thing...
Click to expand...
If you want to quote another post click "reply with quote" in the bottom right of the post you want to quote, if you want to multi quote like I did click on the "+ icon near the same spot in the first post then click "reply with quote" on the last post.

Doctor Electric said:
We are demolishing the old service from the house point down to the panel the service wires I told about in the last quote were the wires coming from the street to the house are the 4 and 2 ot.
Click to expand...
What does this mean? What is the "4 and 2 ot"?

At the house with the delta power I need a neutral so I can use the service for 120/240

Idk maybe I am un clear about what I'm even doing maybe I'll just tell them to demo the 3 phase and bring in another 200 amps it might be cheaper with equipment and time also huh?
Click to expand...

I am still unclear on your situation. This is the first mention of a delta service, which should have a neutral so you shouldn't need to set a transformer for that. Unless its a corner ground it will have a high led so you may want a separate panel for single phase loads fed from A and C phase in your main panel.
 
ActionDave said:
What does this mean? What is the "4 and 2 ot"?

.
Click to expand...
Had me scratching my head a bit, then it hit me it is likely "4/0" AWG and "2/0" AWG.

Now if we just knew how many of each size and if there is a separate single and three phase supply or if there is just one single phase main and one three phase main both fed by the same supply on the existing installation. Still guessing it very likely is an open delta supply, probably would be a good idea, depending on load calculations, utility company costs, etc. to either convert it to just single phase or to convert it to 208/120 three phase.
 
You best talk to the PoCo first. They're the only one who knows where the transformers are, their size and who else utilizes it. They're not in the business of investing money into asset for service or provide demand capacity just cuz you want it. You don't get to name service voltage you want unless they see it as financially sound. The transformer serving the property is the limit on what you can get unless you're going to pay the upgrade and increased running cost or you have something like a pending long term server tenant with anticipated five figure kWh monthly use.

Apartment and office complexes would get 208Y/120 pulled the premise if the average demand and expected kWh usage warrants the cost with predictable long term use and bill revenue once they're fully occupied. These properties are good candidates because they'll usually have a house panel that runs a 3 phase elevator in excess of 5hp (magic # where utility would rather not you go above on single phase) and if present 3 phase pool heat pump/heater that utility would rather not have it on single phase and enough units to make load balancing at property level worthwhile.

The billable kWh used by the elevator motor isn't a whole lot but those properties have enough customers that having load balancing within the premise also benefits the utility. A three phase AC sees significant hours and produce a predictable and sizable revenue but if you have the choice to get rid of it and go single phase, it must be a small unit.
 
No elevator no more 3 phase ac unit they are getting rid of it all I'm gonna be needing is gonna be regular 120/240.

.why would I need the 208 if the new ac units need 240 the 120 208 is less voltage than I need maybe it's better just to get rid of the 3 phase service and bring in another single phase the property is gonna need atleast 400 amps between the two panels

One existing 3 phase service getting demolished One brand new single phase 200 amp to compliment the existing single phase service parallel 200 amp services coming right up
 
I agree with Electric-Light (Post 13). Your first step should be to talk with the PowerCompany and see what is available. As he stated, their transformer may feed additional facilities and for that, and other reasons, you may have no choice as to phase or voltage.
It would also be a good idea to have a load calculation when you talk with them as the load may play into their decision on the supply.
IN addition, selection of the customers equipment will be effected by the available voltage (208 vs 240)
 
No elevator no more 3 phase ac unit they are getting rid of it all I'm gonna be needing is gonna be regular 120/240.

.why would I need the 208 if the new ac units need 240 the 120 208 is less voltage than I need maybe it's better just to get rid of the 3 phase service and bring in another single phase the property is gonna need atleast 400 amps between the two panels

One existing 3 phase service getting demolished One brand new single phase 200 amp to compliment the existing single phase service parallel 200 amp services coming right up
Click to expand...
You mentioned using a wye transformer in the OP. 120/240 single phase is not an available voltage from a wye transformer 208/120 and 480/277 are two most popular voltages available that are under 600 volts.

You need to know what your load calculation is, and determine from that whether or not you want or even can have a single phase service. If you only need 400 amps that is probably acceptable. Start going over that and some POCO's may prefer you go with three phase. If they want you to go three phase you may have to settle for 208/120 even if you prefer a 240 volt system.

There is very few if any air conditioner units out there that are not rated for 208-240 volts, so that shouldn't be too much of an issue if you do need to use a 208 volt system. Biggest advantage of a 208/120 system in a place like you will have is the majority of the equipment is likely 120 volts. If your old three phase system were a 120/240 delta system - you have a high leg and that leg is almost useless to you without transforming it.

One 200 amp 120/240 single phase feed would be able to supply 48000 VA.

One 400 amp 120/240 single phase feed would be able to supply 96000 VA.

One 200 amp 208/120 three phase feed would be able to supply 72051 VA.

Chances are you wouldn't want to be maxed out on any of the above right from initial install, also POCO probably only installs a transformer rated close to the actual load even though you have more capacity in the conductors/overcurrent protection.
 
Doctor electric's profile states that he is an electrician and been in it for five years.

He could be a new EC but he should state that. If he is not the master on this job then the guy with the license should be figureing this stuff out.

It would also help to know what area of the country he is talking about.

In many areas to get a permit for a total remodel like this would require a complete set of approved plans. The should be talking to the POCO engineers but also to the AHJ.
 
Household appliances are made to be compatible with 208 or 240v, because that's just reality. High power commercial microwave ovens that use 208 or 240 has a tapped transformer requiring setting at the time of installation or automatically selected by the appliance through a relay.

Take it like water quality. You don't get to choose hard or soft water that is delivered through the tap.
 
Electric-Light said:
Household appliances are made to be compatible with 208 or 240v, because that's just reality. High power commercial microwave ovens that use 208 or 240 has a tapped transformer requiring setting at the time of installation or automatically selected by the appliance through a relay.

Take it like water quality. You don't get to choose hard or soft water that is delivered through the tap.
Click to expand...
You do have the option of transforming the voltage or treating the water though.
 
Status
Not open for further replies.
Top