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#169298 - 10/01/07 09:23 AM 200 amp 3 phase service?  
sparkync  Offline
Member
Joined: Oct 2002
Posts: 828
NC
Got another situation on another job estimate here. I'm getting a bid together for redoing the service on another church. They currently have a 3 phase 200 amp service with an outside panel,and a smaller outside panel feeding out or it. Then they have a 100 amp breaker feeding
single phase to a main fuse disconnect inside a mechanical room. This disconnect is fused at 150 amps., then feeds into a trough, that then branches out to 2 more disconnects with 60 amp fuses that feeds 2 more electrical panels inside the church, and 2 electric ranges in their kitchen.
There is also another panel coming off the trough that isn't fused that feeds about 4 to 6 120 volt circuits.
They are having trouble with the 60 amp.fuses blowing etc...and a "rat's nest" of wires in the trough. The maintenance electrician that takes care of their church says he has tighten up lugs etc. etc.
What I'm proposing to do is, change all of it out and put them a new panel outside and combine the panels on the inside to one 200 amp panel. My original idea was to just change the outside to a 225 amp 3 phase, (leaving the actual meter base that is there if it was rated for 225 amps), and feed the inside panel 200 amps. Problem here is feeding the inside panel. I found out that they now make a 200 amp. plug in breaker ( Square D ) but I don't want to go that route if I don't have to. It will be terribly hard (if not suicidal) to try and use 3/0 copper and bend it to go into a plug in breaker, then go back out of the back of the panel, into an LB and back up into the conduit.
My next option was to change the service to 400 amp 3phase and come off the dual lugs of the meter base for the feed to the 3 phase panel, then off again to the single phase panel to a 200 amp main breaker disconnect for the inside panel. Trouble with this is, I'm not sure about coming off the 3 phase meter with single phase to the other disconnect, and keeping the unbalanced load correct.
Wonder if anyone could give me some options as to the best way to do this? Thanks Steve...
By the way, thanks for the input on the bid for the other job. I'm still waiting to here from the customer on my preliminary bid.

Last edited by sparkync; 10/01/07 09:27 AM.

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#169300 - 10/01/07 09:53 AM Re: 200 amp 3 phase service? [Re: sparkync]  
Jps1006  Offline
Member
Joined: Jan 2004
Posts: 615
Northern IL
Picture would be worth some words here. Just remember to remind them that all this changing feeds and panels will probably not correct the blowing fuses. I suspect those 4-6 120-volt circuits are overloaded.


#169312 - 10/01/07 02:35 PM Re: 200 amp 3 phase service? [Re: Jps1006]  
sparkync  Offline
Member
Joined: Oct 2002
Posts: 828
NC
JPS, the 120 volt circuits are not what's blowing. They are fortunately on breakers. It was the 60 amp fuses that are feeding other panels. They have a "rats nest" connection on the neutrals in the trough. I may have to run new feeders to one of the panels, once I get the mess cleaned up. The panel may be overloading the fuse. Everythng's "old"; the wiring, disconnects etc.. except the few breaker circuit panels that have been added over the years. As far as the picture goes, unfortunately, my computer does not have the "port" needed to send pictures. My son's my computer expert and we are thinking about upgrading as soon as possible. I guess my main concern now is trying to put a 200 amp single phase breaker ahead of the inside panel out of a 3 phase panel on the outside. Thanks, Steve...


#169315 - 10/01/07 05:21 PM Re: 200 amp 3 phase service? [Re: sparkync]  
ghost307  Offline
Member
Joined: May 2005
Posts: 916
Chicago Illinois USA
The 120V circuits may still be the overall problem.

If they're drawing a total amperage that's causing the 60A fuses to blow, then there's still an issue that increasing the incoming power won't address.

Amprobe the 120V circuits when they're loaded and see if they might be contributing to the situation.


Ghost307

#169319 - 10/01/07 07:37 PM Re: 200 amp 3 phase service? [Re: ghost307]  
wire_twister  Offline
Member
Joined: Jul 2007
Posts: 265
Georgia USA
jps,
I dont know what is causing the fuses to blow, but I just installed a service just like you are talking about, 3 phase on 1 side single phase on the other. my service was 230v delta with a high leg. I did not experience any major imbalance with the single phase load on just two legs of the meter. The three phase panel just carried the AC load in this church, not a small load about 20 tons!!


Jimmy

Life is tough, Life is tougher when you are stupid

#169321 - 10/01/07 09:34 PM Re: 200 amp 3 phase service? [Re: wire_twister]  
sparkync  Offline
Member
Joined: Oct 2002
Posts: 828
NC
wire_twister, I think that is all that is fed from this panel also is just the A/C units. One is on a 60 amp 3 phase breaker and the other one is on a 20 amp.

As far as the fuses blowing. That is not the only reason we're changing this service. There are quiet a few other code violations that I didn't mention. The main fuse disconnect that feeds into the traugh didn't have a neutral pulled in with it. One of the 60 amp disconnects also has a 240 volt circuit coming off it that feeds into a 4 11/16 box, where it is spitbolted and feeds (2) 3 wire range recptacles, and they are waiting til this wiring is straighted out so they can add a 3rd. This same disconnect feeds another 8 or ten circuit panel inside the church.
Not to mention the piece of ground rod outside that was laying on the ground, and when the maintenance man stuck it back in the ground it can be easily pulled up. The wires feeding the 150 amp main fused disconnect have had their strands cut out so they would fit in the lugs, also on the main breaker side of it on the outside. So many it would take too long to list them all probably. That is the reason we decided to redo it all. I'll probably go with a 320 amp meter base with dual lugs, if it comes that way in 3 phase, and go to the 3 phase panel for the A/c loads and the other outside loads, then come off the other lugs to feed a 200 amp "mobile home" type panel with the feed through lugs on the bottom. That way there will be room for a few other circuits outside in the future if needed. Anybody see anything wrong with this idea? Thanks, Steve..



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