120/240 3 phase

[bobbymari]

have a setup which has 2 operating systems 120/240 single phase setup as well as a newer 120/240 volt 3 phase setup with transformer converting 3 phase to 208. my question is this. they have a work shop with 240 volt welders and such and my plan was to take the 240 3phase to a sub pnl back there which would be supplied from the 240v 3 phase equiptment load center before the 208 conversion transformer. any problems with this? I want them to have the actual 240 back there. there is a nuetral available as well so i plan to send that back also to the sub for gen purpose recepts and lights. im aware of the 240 stinger to ground. just curious if i can utilize the 240 load center before it hits transformer and is converted to 208. i dont think neutral balancing is an issue since there is only one 3 phase drop to bldg and there single phase setup is off of same drop and they just left of one phase to metering equiptment anyways

 

[augie47]

If you elect to run a neutral, you need to keep 215.2 in mind.
If "back there" is a separate building there are a number of Code sections you need to keep i n mind.

 

[bobbymari]

where im landing sub is same building but out of that will be feeding work area which is detached i am running egc to sub but since the work area sub will feed is detached will this require electrode system? is that what youre referring to on things to keep in mind?

 

[Smart $]

Generally, the first place to start is of course a load calculation to be sure the service has the capacity to add the load of a subpanel. And with the system set up as you have described, you will have to determine how well balanced the system is. I'm thinking the 208Y/120V was installed to help with balancing 120V load to all three phases. You may also need to determine if the service transformers and conductors can adequately supply the service at its full 3? rating, especially if supplied open delta. You may have to contact the POCO for assistance with transformer ratings or service capacity.

 

[augie47]

If you are feeding a sub-panel in a detached building:
215,2, All of Art 225 and 250.32 including the need for a grounding electrode system.

 

[Smart $]

where im landing sub is same building but out of that will be feeding work area which is detached i am running egc to sub but since the work area sub will feed is detached will this require electrode system? is that what youre referring to on things to keep in mind?

Don't quite understand. Is the work area outside the main structure, or inside another [detached] structure? You can only run one feeder or branch circuit to another structure.

 

[bobbymari]

gotcha yea those articles are definetly in plans, as well as electrode system. And sorry I mwasn't really clear on original post. all of this equipt. is already in use, not adding anyload just starting to cleanup all the makeshift work that has been done and double check myself before hand. The area is already supplied via a way undersized 2 wire j cord with groundwhich they are using as a neutral running about 200' . about 1/2 way there the j cord hits a spider box which has a 100 amp breaker in it and out of that theyve pluged in another jcord to feed work area subpanel with 4) 50 amp recetacles all being tappedinto subpanel main lugs. i swear im not making this up

 

[augie47]

Sounds like a real "opportunity"

 

[bobbymari]

my exact thoughts as soon as i took one look

 

[jim dungar]

My preference is to use two panels, one for 3-phase 240V and the other for 120/240 1PH loads. Not as much chance of issues with the high-leg and 'unused' spaces that occur in a standard bussed panel.

 

[augie47]

On a side note, don't forget 240.85, 408.3(F) and 408.58 when dealing with your high-leg panel.

 

[bobbymari]

jim by 2 panels do you mean a secondary panel off of the 3 phase panel? Such as feeding the single phase panel with a 3 phase breaker but only using the outer lugs of the breaker and not using stinger?

 

[bobbymari]

augie yea quote i got from supplier are actual 240v 3 phase subs which should be labeled as such, if not they will be when I leave. Y our reminders are awesome. Thanks bro

 

[bobbymari]

smart, work area is outside. basically just 4x4 posts with plastic awning. posts and awning are bolted to building so technically I guess you could say it's attached but want to give all this a good grounding system, which is why I was going to include electrode system" couldn't hurt" in my opinion. But where I am actually placing the sub is definetly attached to bldg.

 

[Smart $]

My preference is to use two panels, one for 3-phase 240V and the other for 120/240 1PH loads. Not as much chance of issues with the high-leg and 'unused' spaces that occur in a standard bussed panel.

240V 1?, 2-wire loads can be installed in either panel and are often used to balance the system.

 

[jim dungar]

jim by 2 panels do you mean a secondary panel off of the 3 phase panel? Such as feeding the single phase panel with a 3 phase breaker but only using the outer lugs of the breaker and not using stinger?

Yeah, but you can use a 2-pole breaker in the 3-Ph panel.

 

[bobbymari]

is there a way to upload a quick drawing as I may not be making myself clear about this install

 

[Smart $]

is there a way to upload a quick drawing as I may not be making myself clear about this install

What is the file format (i.e. extension)? On the Post Reply page, in the Additional Options section, click on the Manage Attachments button. A File Upload Manager window will pop up. In the upper right corner, click on the "?" button. A pop up will appear that list file formats and sizes that will upload. Then use the "+ Add Files" button just below the "?" button.

If you can upload to a web server, you can also link to it here (or use tags to display it here if an image file).

 

[bobbymari]

i have it on a word document format

 

[Smart $]

i have it on a word document format

It'll have to be saved in the *.doc format.... *.docx won't upload.