# X-fmer's roughed in the slab



## william1978 (Sep 21, 2008)

Do any of you rough your x-fmers in the slab if it is possible or do you just flex them in?


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## william1978 (Sep 21, 2008)

Here is are some pictures of a baby x-fmer that I roughed in the slab.


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## B4T (Feb 10, 2009)

I always use flex in case it has to be changed.. being fed from the bottom is a real PITA when you don't have use of a fork lift


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## Bob Badger (Apr 19, 2009)

william1978 said:


> Do any of you rough your x-fmers in the slab if it is possible or do you just flex them in?


I have not , but if the opportunity presented itself I would not hesitate. I have dropped down to floor below and back up again.


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## 480sparky (Sep 20, 2007)

Depends on the job. If I have the opportunity, yes. But some jobs, like precast mezzanines, don't lend themselves to it.


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## B4T (Feb 10, 2009)

Why would they bottom feed them that way to begin with?

Seems like really poor engineering for something that weighs hundreds of pounds


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## william1978 (Sep 21, 2008)

480sparky said:


> Depends on the job. If I have the opportunity, yes. But some jobs, like precast mezzanines, don't lend themselves to it.


 Thats the way I do it also. PVC is a whole lot cheaper than flex 90's.


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## Bob Badger (Apr 19, 2009)

Black4Truck said:


> Why would they bottom feed them that way to begin with?
> 
> Seems like really poor engineering for something that weighs hundreds of pounds



It keeps the transformer from cooking the insulation on the conductors.

I have wired a 1000 KVA that was top feed but there was a ton of air space and venting.


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## william1978 (Sep 21, 2008)

Black4Truck said:


> Why would they bottom feed them that way to begin with?
> 
> Seems like really poor engineering for something that weighs hundreds of pounds


 It is a whole lot easier to pull the wire when it is in the slab than fight those 90 degree flex conn. I rough mine with 2 90's back and if you tape the wires together and push the wire so that the wire is curled the way the 90's are going the wire will come right out of the other end.


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## 480sparky (Sep 20, 2007)

Black4Truck said:


> Why would they bottom feed them that way to begin with?
> 
> Seems like really poor engineering for something that weighs hundreds of pounds


 
What does the weight of the equipment got to do with it? The only problem with weight you could possibly have is if the _floor_ is poorly engineered. I've installed switchgear that far outweighs any transformer in the room and it's bottom fed....


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## william1978 (Sep 21, 2008)

Here are some photos of the panel's that are on the opposite wall.


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## B4T (Feb 10, 2009)

480sparky said:


> What does the weight of the equipment got to do with it? The only problem with weight you could possibly have is if the _floor_ is poorly engineered. I've installed switchgear that far outweighs any transformer in the room and it's bottom fed....


I am talking about having to change the transformer

The ones in the pic, I could use a hand truck to get it out of the space

With bottom feed, that option won't work


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## 480sparky (Sep 20, 2007)

Black4Truck said:


> I am talking about having to change the transformer
> 
> The ones in the pic, I could use a hand truck to get it out of the space
> 
> With bottom feed, that option won't work


 
How often does this actually happen?


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## william1978 (Sep 21, 2008)

480sparky said:


> How often does this actually happen?


My exact thought. I have never had to replace a x-fmer.


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## 480sparky (Sep 20, 2007)

william1978 said:


> My exact thought. I have never had to replace a x-fmer.


When I designed my house, everyone told me I was nuts for not having the garage right off the kitchen. I asked why I needed to do so. Everyone said "So when you replace your refrigerator, it will be easy to get the new one in and the old one out!"

I have yet to replace my fridge, and will probably do so only once in the remainder of my life. 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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## B4T (Feb 10, 2009)

william1978 said:


> My exact thought. I have never had to replace a x-fmer.


So far, I have had to change (3) of them

One was being fed from the bottom with 500 cu and I will never do that kind of job again.. total PITA bending wires to make them fit


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## 480sparky (Sep 20, 2007)

Black4Truck said:


> So far, I have had to change (3) of them
> ............


Mebbe you should start supplying better transformers, then. :laughing:


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## B4T (Feb 10, 2009)

480sparky said:


> Mebbe you should start supplying better transformers, then. :laughing:


Mine are all still working fine, it was the other guy who was supplying cheap transformers


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## william1978 (Sep 21, 2008)

480sparky said:


> ....., sit at the computer and post on ET...........


 You know thats right.:thumbup:


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## 480sparky (Sep 20, 2007)

Black4Truck said:


> Mine are all still working fine, it was the other guy who was supplying cheap transformers


Then thank him for the work. :thumbsup:


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## EJPHI (May 7, 2008)

*nice transformer pics!!*

Please unconfuse me :jester:about some of the wiring:

This first pic looks like transformer is wired for 480 delta to 208 wye


In the next one, the connection looks like 480 wye.

It just seems unusual to me that you would have 480 delta and wye in the same installation. 

What am I missing?

Thank you
EJPHI


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## william1978 (Sep 21, 2008)

You didn't miss anything. The transformer doesn't need a neutral on the primary side it is recreating the neutral for the secondary side. I'm going to see if I can find a wiring digram.


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## 480sparky (Sep 20, 2007)

william1978 said:


> You didn't miss anything. The transformer doesn't need a neutral on the primary side it is recreating the neutral for the secondary side. I'm going to see if I can find a wiring digram.


 
Dis do it?


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## william1978 (Sep 21, 2008)

480sparky said:


> Dis do it?


 That is what I was looking for. Thanks 480.:thumbsup:


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## Decepticon (Oct 4, 2009)

480sparky said:


> When I designed my house, everyone told me I was nuts for not having the garage right off the kitchen. I asked why I needed to do so. Everyone said "So when you replace your refrigerator, it will be easy to get the new one in and the old one out!"
> 
> I have yet to replace my fridge, and will probably do so only once in the remainder of my life. 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...........


That's the reason why I put the garage near the kitchen. We're always taking in groceries and other stuff from the cars, the kitchen is the "headquarters" where everything lands before it is put away.


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## Decepticon (Oct 4, 2009)

Hey William, I guess in your area you won't get gigged for using white instead of gray for the high voltage noodle?


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## 480sparky (Sep 20, 2007)

Decepticon said:


> Hey William, I guess in your area you won't get gigged for using white instead of gray for the high voltage noodle?


 
Got a Code reference? :whistling2:

Besides, the noodle is for the 120/208 side, not the 480 side.


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## william1978 (Sep 21, 2008)

Decepticon said:


> Hey William, I guess in your area you won't get gigged for using white instead of gray for the high voltage noodle?


It is gray tape it does look like white tape in the picture, but even if it was white the inspector couldn't say a thing and it should be that way in your area also.


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## Decepticon (Oct 4, 2009)

480sparky said:


> Got a Code reference? :whistling2:


 There's a lot of things that get gigged that aren't in the code.


> Besides, the noodle is for the 120/208 side, not the 480 side.


Not in the picture I am looking at.


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## william1978 (Sep 21, 2008)

Decepticon said:


> Hey William, I guess in your area you won't get gigged for using white instead of gray for the high voltage noodle?


 Are we talking about the x-fmer or the panelboard?


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## 480sparky (Sep 20, 2007)

Decepticon said:


> There's a lot of things that get gigged that aren't in the code.............
> 
> Do you ask for a Code reference then?





Decepticon said:


> ...........Not in the picture I am looking at.


Uncle! Which one you looking at then?


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## Decepticon (Oct 4, 2009)

william1978 said:


> Are we talking about the x-fmer or the panelboard?


I was looking at this picture:









But maybe it's just the coloring on my computer making it look white instead of gray


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## william1978 (Sep 21, 2008)

Decepticon said:


> There's a lot of things that get gigged that aren't in the code.
> 
> 
> Not in the picture I am looking at.





Decepticon said:


> I was looking at this picture:
> 
> 
> 
> ...


 It does look white in that picture. Check it out in the other pictures. It is gray that is what we use on our 480v.:thumbsup:


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## 480sparky (Sep 20, 2007)

Decepticon said:


> I was looking at this picture:
> 
> But maybe it's just the coloring on my computer making it look white instead of gray


 
I see it as white, too, but I can see where it_ is_ overexposed.


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## Decepticon (Oct 4, 2009)

william1978 said:


> It is gray that is what we use on our 480v.:thumbsup:


Us too, but I have seen and heard about some pretty wacky color coding around the country, which is why I was curious about yours. I'm glad I could go to NC and know WTF is going on :thumbup::thumbsup:


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## william1978 (Sep 21, 2008)

Decepticon said:


> Us too, but I have seen and heard about some pretty wacky color coding around the country, which is why I was curious about yours. I'm glad I could go to NC and know WTF is going on :thumbup::thumbsup:


Everyone that I know uses gray for highvolt and white for lowvolt. We do have some delta highleg in some of the older area's. So whenever you fell like moving come on over to N.C..:thumbsup:


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## 480sparky (Sep 20, 2007)

william1978 said:


> Everyone that I know uses gray for highvolt and white for lowvolt. We do have some delta highleg in some of the older area's. So whenever you fell like moving come on over to N.C..:thumbsup:


Just wait until you find gray that was installed (legally!) as an _ungrounded!_


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## william1978 (Sep 21, 2008)

480sparky said:


> Just wait until you find gray that was installed (legally!) as an _ungrounded!_


 Haven't yet, but who know's oneday I just might.:thumbsup:


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## rlc3854 (Dec 30, 2007)

william1978 said:


> It does look white in that picture. Check it out in the other pictures. It is gray that is what we use on our 480v.:thumbsup:


 
Check out the other three cables in the upper left side. They look gray:thumbsup:


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## micromind (Aug 11, 2007)

I've changed out maybe 3 or 4 transformers that were bottom fed so far. The smallest was likely a 15 KVA, the largest was a 300. 

It's really not all that hard, just spoon it up onto some blocks, a little on each side at a time. Get it high enough to put some short pieces of 4" or 6" rigid under the end rails, and try to not skin up the wires as it rolls out. 

That can be sort of hard if they're 500s. Some transformers you can take the bolts out of the back of the bottom plate, and tip it up a bit. This helps more than you'd think; not only do you have more clearance, but the holes in the bottom plate are now angled slightly to your favor. 

If the transformer is on a housekeeping pad, this method becomes much more difficult. It's best to build something up to the height of the pad, so the pipes have something to roll out onto. A couple of 4x8s work pretty good.

Having more than one person helps a bunch. 3 of us did the 300, it went pretty well. 

If the transformer isn't too heavy, a cherry picker (the kind used to pull a car engine) is the absolute best possible way, if it'll fit in the room, and straddle the pad. 

Rob


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## william1978 (Sep 21, 2008)

rlc3854 said:


> Check out the other three cables in the upper left side. They look gray:thumbsup:


 Yea, I noticed that.:thumbsup:


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## william1978 (Sep 21, 2008)

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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## rlc3854 (Dec 30, 2007)

Oh, and by the way William that sure is some pretty work-beautiful.


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## william1978 (Sep 21, 2008)

rlc3854 said:


> Oh, and by the way William that sure is some pretty work-beautiful.


 Thank you.:thumbsup:


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## EJPHI (May 7, 2008)

*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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## william1978 (Sep 21, 2008)

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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## william1978 (Sep 21, 2008)

EJPHI are a engineer?


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## EJPHI (May 7, 2008)

EJPHI are an inguneer. The electronical kind not the choo-choo kind.

EJPHI


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## 220/221 (Sep 25, 2007)

> 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...........


And carry in groceries :whistling2:

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 :jester:


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## B4T (Feb 10, 2009)

EJPHI said:


> EJPHI are an inguneer. The electronical kind not the choo-choo kind.
> 
> EJPHI


I have no idea what he is saying......


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## user4818 (Jan 15, 2009)

Black4Truck said:


> I have no idea what he is saying......


Those who operate trains are also referred to as engineers.


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## EJPHI (May 7, 2008)

Black4Truck said:


> I have no idea what he is saying......


You are not alone. 

Sometimes I don't either


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## randas (Dec 14, 2008)

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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## micromind (Aug 11, 2007)

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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## william1978 (Sep 21, 2008)

The POCO around here will not cut on a transformer that doesn't have a grounded conductor in the conduit.


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## JohnJ0906 (Jan 22, 2007)

william1978 said:


> The POCO around here will not cut on a transformer that doesn't have a grounded conductor in the conduit.


They don't provide Delta services?


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## william1978 (Sep 21, 2008)

JohnJ0906 said:


> They don't provide Delta services?


 No.........


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## EJPHI (May 7, 2008)

micromind said:


> 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.
> 
> ...


 
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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## manchestersparky (Mar 25, 2007)

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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