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10-04-2009, 09:16 PM
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#41
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Unlimited Lic.Electrician
Join Date: Sep 2008
Location: Charlotte N.C.
Posts: 7,788
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Quote:
Originally Posted by rlc3854
Check out the other three cables in the upper left side. They look gray  |
Yea, I noticed that.
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10-04-2009, 09:20 PM
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#42
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Unlimited Lic.Electrician
Join Date: Sep 2008
Location: Charlotte N.C.
Posts: 7,788
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If I had to replace a X-fmer I think I would take the top off and use a cherry picker and unbolt the x-fmer from the housing and lift it strait out of the top. You wouldn't have mess with knocking out the holes in the new housing or mess withe the wires execpt reterminating them.
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10-04-2009, 09:28 PM
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#43
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Senior Moment
Join Date: Dec 2007
Location: Amite, LA
Posts: 459
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Oh, and by the way William that sure is some pretty work-beautiful.
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10-04-2009, 09:29 PM
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#44
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Unlimited Lic.Electrician
Join Date: Sep 2008
Location: Charlotte N.C.
Posts: 7,788
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Quote:
Originally Posted by rlc3854
Oh, and by the way William that sure is some pretty work-beautiful.
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Thank you.
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10-05-2009, 02:47 AM
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#45
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Member
Join Date: May 2008
Location: N California
Posts: 40
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transformer wiring
William / 480,
Thanks for the diagram:
Quote:
Originally Posted by 480sparky
Dis do it?
So this idea is to delta connect the wye 480 to the transformer by leaving off the neutral. I understand that most transformers use a delta primary. But now I need to think hard about any problems this might cause in the overall system.
Are there many loads that use 480 wye, so that making up the whole system as 480 delta would not work? Saving the cost of the neutral might be worthwhile system-wide.
The delta connected transformer primary could potentially have a phase current imbalance that would have otherwise been carried by the primary neutral connection (if wye).
Also I thought harmonic currents would cause more heating in delta than in wye.
Time to put on my thinking cap.
Thanks for the education.
EJPHI
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10-05-2009, 04:58 PM
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#46
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Unlimited Lic.Electrician
Join Date: Sep 2008
Location: Charlotte N.C.
Posts: 7,788
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I had lights that were 277v so in my case I did need the neutral,but if there was no neutral load you could do without the neutral I suppose.
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10-05-2009, 04:59 PM
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#47
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Unlimited Lic.Electrician
Join Date: Sep 2008
Location: Charlotte N.C.
Posts: 7,788
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EJPHI are a engineer?
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10-05-2009, 05:31 PM
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#48
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Member
Join Date: May 2008
Location: N California
Posts: 40
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EJPHI are an inguneer. The electronical kind not the choo-choo kind.
EJPHI
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10-05-2009, 06:11 PM
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#49
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Senior Member
Join Date: Sep 2007
Location: Phoenix, AZ
Posts: 1,161
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Quote:
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I would prefer to have a house designed around the things I do every day, like cook, do laundry, sit at the computer and post on ET...........
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And carry in groceries 
I put my laundry room next to the bedroom so I don't have to drag the laundry across the house and back. It seems to me that a well designed house would always have the laundry close to where the clothes are but they still always put them across the house by the kitchen/garage.
Crap....I forgot what the thread was about 
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10-05-2009, 06:26 PM
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#50
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B4T Scotchkote installer
Join Date: Feb 2009
Location: Long Island, N.Y.
Posts: 4,483
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Quote:
Originally Posted by EJPHI
EJPHI are an inguneer. The electronical kind not the choo-choo kind.
EJPHI
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I have no idea what he is saying......
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10-05-2009, 06:32 PM
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#51
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Not Peter D
Join Date: Jan 2009
Location: USA
Posts: 5,437
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Quote:
Originally Posted by Black4Truck
I have no idea what he is saying......
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Those who operate trains are also referred to as engineers.
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10-05-2009, 07:20 PM
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#52
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Member
Join Date: May 2008
Location: N California
Posts: 40
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Quote:
Originally Posted by Black4Truck
I have no idea what he is saying......
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You are not alone.
Sometimes I don't either
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10-06-2009, 12:11 AM
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#53
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Member
Join Date: Dec 2008
Location: Canada
Posts: 82
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I like roughing em in the slab. What I do is stub up beside the xmfr into a JB bolted to the side of the xmfr. Makes it much easier to replace.. and pull the wire too.
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10-06-2009, 12:36 AM
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#54
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Bilge Rat
Join Date: Aug 2007
Location: Fernley, Nevada (near Reno)
Posts: 651
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Going back a few posts, there are basically two reasons I can think of as to why most 480 volt services are wye;
1) 277 is available for lighting. This can be the majority of the load in a lot of buildings.
2) The maximum voltage to ground is 277. If the service was 480 grounded B, two legs would be 480 to ground. If it was a 4 wire delta, two legs would be 240 to ground, and the other one would be 416 to ground. Obviously, a wye is slightly safer.
There are a few reasons why most transformers are delta/wye.
1) A closed delta connection tends to balance voltage. A wye/wye will pass any imbalance through.
2) Coil and core heating is a bit more evenly distributed when a current imbalance exists on the secondary.
3) A current imbalance in the secondary results in less of an imbalance in the primary.
4) A delta/wye tends to diminish the effects of harmonics passed back to the primary. A wye/wye tends to magnify it.
I'm sure there are others, these are just what comes to mind right now.
Rob
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10-06-2009, 04:44 PM
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#55
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Unlimited Lic.Electrician
Join Date: Sep 2008
Location: Charlotte N.C.
Posts: 7,788
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The POCO around here will not cut on a transformer that doesn't have a grounded conductor in the conduit.
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10-06-2009, 06:52 PM
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#56
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Senior Member
Join Date: Jan 2007
Location: Baltimore, MD, USA
Posts: 3,490
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Quote:
Originally Posted by william1978
The POCO around here will not cut on a transformer that doesn't have a grounded conductor in the conduit.
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They don't provide Delta services?
__________________
John from Baltimore
"One day at a Time"
All responses based on the '08 NEC
It's not my fault, it's not my problem, I'm not your solution. 
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10-06-2009, 09:36 PM
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#57
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Unlimited Lic.Electrician
Join Date: Sep 2008
Location: Charlotte N.C.
Posts: 7,788
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Quote:
Originally Posted by JohnJ0906
They don't provide Delta services?
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No.........
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10-08-2009, 02:00 AM
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#58
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Member
Join Date: May 2008
Location: N California
Posts: 40
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Quote:
Originally Posted by micromind
Going back a few posts, there are basically two reasons I can think of as to why most 480 volt services are wye;
1) 277 is available for lighting. This can be the majority of the load in a lot of buildings.
2) The maximum voltage to ground is 277. If the service was 480 grounded B, two legs would be 480 to ground. If it was a 4 wire delta, two legs would be 240 to ground, and the other one would be 416 to ground. Obviously, a wye is slightly safer.
There are a few reasons why most transformers are delta/wye.
1) A closed delta connection tends to balance voltage. A wye/wye will pass any imbalance through.
2) Coil and core heating is a bit more evenly distributed when a current imbalance exists on the secondary.
3) A current imbalance in the secondary results in less of an imbalance in the primary.
4) A delta/wye tends to diminish the effects of harmonics passed back to the primary. A wye/wye tends to magnify it.
I'm sure there are others, these are just what comes to mind right now.
Rob
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Micromind;
All i can say is DOOH! I forgot about the lighting load.
Pardon the pun, but your comments above were quite illuminating!
I will give this some more pondering.
EJPHI
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10-17-2009, 08:47 AM
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#59
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Professional Nit Picker
Join Date: Mar 2007
Location: Maryland
Posts: 652
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Let me play devils advocate here.....
The transformer in the picture does not have a factory "open bottom", but rather a slotted " vented" bottom.
In the 2008 NEC Section 300.12 Mechanicl Continuity -
"Raceways and cable sheaths shall be mechanically continuous."
You can not just cut a hole and stub a conduit up into it any more.
The one in the pictures is installed just that way. Those pvc Bell ends are not connectors. SO that means that there is no Mechanical Continuity.
To acheive mechanical Continuity you must use an approved conector that is connected directly to the transformer.
Comments ?????
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