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 DIY Chatroom Home Improvement Forum My electrical adventure from a few days ago

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06-10-2010, 04:42 PM   #16
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Quote:
 Originally Posted by Red Squirrel I understand the secondary side with the tap, but what about the primary side? don't you need two wires going into a transformer, and at least two coming out? Or does the neutral just bypass the whole transformer and go straight to the house? Did not figure that could work. This is how I figured it had to work:

The primary of your house transformer is connected to the secondary of the distribution transformer. The H and H on your drawing would be connected to N and A (or B or C). Because N is grounded at the source, it can be grounded along the way too.
As mentioned, grounding is a safety thing and one thing it does is keeps everything at a common reference.
Even though N is grounded, it is still a current carrying conductor and technically called the Grounded Conductor.
The secondary of your house transformer is center tapped and the tap is grounded. The neutral buss and the ground buss in your main panel are bonded so there isn't ground loops on the service side of the main panel unless the neutral is open between the transformer and the neutral buss. BTW, the neutral line between the transformer and main panel only carries the difference in current between the two buss bars. If one buss is drawing 40 amps and the other buss is drawing 30 amps, the neutral only as 10 amps of current.
Hope this keeps you awake for awhile tonight

Quote:
 Originally Posted by Red Squirrel The low voltage line is on the secondary side of the transformer though, how is the primary fed with just one wire? I can't see properly how it's wired though because of a tree in my path of view. Maybe there's a feed coming from the ground up the pole through a conduit or something to feed the second conductor. Can't see why they'd seperate them like that though.
That is because inside the transformer the one side of the primary is tied directly to the center tap on the secondary.
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06-10-2010, 05:39 PM   #17
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Quote:
 Originally Posted by a7ecorsair The primary of your house transformer is connected to the secondary of the distribution transformer. The H and H on your drawing would be connected to N and A (or B or C). Because N is grounded at the source, it can be grounded along the way too. As mentioned, grounding is a safety thing and one thing it does is keeps everything at a common reference. Even though N is grounded, it is still a current carrying conductor and technically called the Grounded Conductor. The secondary of your house transformer is center tapped and the tap is grounded. The neutral buss and the ground buss in your main panel are bonded so there isn't ground loops on the service side of the main panel unless the neutral is open between the transformer and the neutral buss. BTW, the neutral line between the transformer and main panel only carries the difference in current between the two buss bars. If one buss is drawing 40 amps and the other buss is drawing 30 amps, the neutral only as 10 amps of current. Hope this keeps you awake for awhile tonight
I take bus to school or I get grounded....

Seriously, that's great information.

06-10-2010, 05:42 PM   #18
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Quote:
 Originally Posted by a7ecorsair That is because inside the transformer the one side of the primary is tied directly to the center tap on the secondary.
Interesting, so is it more something like this?

This is what I believe my setup is like. I will have to check it out next time I go outside, but pretty sure.
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06-10-2010, 05:50 PM   #19
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Quote:
 Originally Posted by Red Squirrel Interesting, so is it more something like this? This is what I believe my setup is like. I will have to check it out next time I go outside, but pretty sure.
Looks good but didn't you say there were two wires on the pole going to the transformer?
What are you using to draw this? I used Paint and free-handed the transformer windings.

Quote:
 Originally Posted by Troglodyte I take bus to school or I get grounded.... Seriously, that's great information.
Ya, I noticed the bus and buss but didn't feel like editing the post. This way I know somebody read it

06-10-2010, 05:59 PM   #20
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Quote:
 Originally Posted by a7ecorsair Looks good but didn't you say there were two wires on the pole going to the transformer? What are you using to draw this? I used Paint and free-handed the transformer windings.

Nope only one wire, which is what had me stumped as I always thought there had to be at least two. A positive and negative (if you were to freeze time) but guess not, as the other can be ground.

And yeah I'm just using good ol MS paint lol. I don't know why but the mspaint at work can save to jpg but mine can't, so I had to move it in photoshop, and while I was there I added a few more things, then saved as png.

 06-11-2010, 07:09 AM #21 Member   Join Date: May 2010 Posts: 38 Rewards Points: 25 So what happens if the ground at the transformer comes loose? Does that mean the end users are then grounding the transformer through their grounds?
 06-11-2010, 08:23 AM #22 I=E/R     Join Date: May 2010 Location: Minnesota Posts: 2,052 Rewards Points: 1,000 RS, just to satisfy my curiosity, you need to look at that transformer with a pair of binoculars. If there is only one connection to the transformer from the distribution system then there would have to be the same size conductor going to ground. If it ever stops raining, I'm going to take a picture of my transformer and post it.
06-11-2010, 09:14 AM   #23
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Quote:
 Originally Posted by a7ecorsair RS, just to satisfy my curiosity, you need to look at that transformer with a pair of binoculars. If there is only one connection to the transformer from the distribution system then there would have to be the same size conductor going to ground. If it ever stops raining, I'm going to take a picture of my transformer and post it.
I'll see if I can do that. Maybe next time I get on my roof I'll get a better view. Also with a setup like this, how would the power plant generator be wired, or the next transformer down the line? Would it also have one wire going to ground and the ground is the 2nd conductor? since you need a complete circuit.

 06-11-2010, 09:29 AM #24 I=E/R     Join Date: May 2010 Location: Minnesota Posts: 2,052 Rewards Points: 1,000 If what you say about only one wire connected, then earth would have to be the other. Distribution systems are a different world compared to what we see in a house but somehow there has to be a complete circuit for the primary side of the transformer.
 06-11-2010, 01:02 PM #25 I=E/R     Join Date: May 2010 Location: Minnesota Posts: 2,052 Rewards Points: 1,000 This pictures shows the transformer connections. The three on the side are the secondary outputs with the middle being the neutral. This transformer serves two meters, mine and the neighbors. My connections are the larger wires on the outer to lugs and the neighbor's is the two that loop off to the right. The middle goes to the other side of the pole which will show in the next picture. In the upper left is a coiled wire coming down from the hot feed and it goes to the spring loaded fuse mounted on the transformer. Notice the ground wire from the center lug that goes to the pole and then to a ground rod. Next picture please. I don't know how to get two pictures in one post so see the next posting. Attached Thumbnails   Last edited by a7ecorsair; 06-11-2010 at 01:12 PM.
 06-11-2010, 01:11 PM #26 I=E/R     Join Date: May 2010 Location: Minnesota Posts: 2,052 Rewards Points: 1,000 In this picture of the other side of the pole you can see the neutral connection and the two secondary hots going down the PVC The heavy wire from the center tap is connected directly to the distribution neutral which is shown tied to the insulator. The way this is set up my neutral line is actually tied directly to the distribution neutral. So you can see that this system has a distribution neutral that is grounded to earth and also tied to the secondary neutrals that go to the two residences. Attached Thumbnails
 06-11-2010, 02:25 PM #27 Wire Chewer     Join Date: Jun 2009 Location: Ontario, Canada Posts: 3,550 Rewards Points: 528 I took a closer look today and it does look like mine is setup similar, I did not notice if there is a PVC going down, but there might be. Lot of trees in the area and it's behind houses so hard to get a good look at. It's cool to be able to see and understand parts of the grid though.
 06-12-2010, 02:40 AM #28 " Euro " electrician     Join Date: Apr 2006 Location: WI & France { in France for now } Posts: 5,369 Rewards Points: 2,000 The primary and secondary netural are used with common netrual conductor so that why they use one less wire for primay and secondary netural and I have run into like this set up more than I can recall. If you look back to the posting #12 what RS did have the image and look at it for a second and look at secondary netural conductor and next part is look at primary netual conductor which it will be on the bottom part both are tied together. Yeah for ground protection every post will have a ground pad or rod one of the two it will be well set up for both lighting protection and also used for distubruion ground point { this part I am not crazy if you loose primary netural it get hair rasing event } Merci,Marc
 06-12-2010, 11:04 AM #29 Wire Chewer     Join Date: Jun 2009 Location: Ontario, Canada Posts: 3,550 Rewards Points: 528 I've been noticing even 3 phase poles and even those just use one wire per transformer. Instead of just one transformer, there will be 3, then the wires split off to different parts. Sometimes there's still just 1 transformer but it still tapes off only one wire even if there are 3. Funny as I never noticed that before. But yeah, what happens if the ground is lost at the pole? Like any vandal could go there and cut it (probably get a nice arc flash in the face in the process)
06-12-2010, 04:22 PM   #30
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Quote:
 Originally Posted by Red Squirrel But yeah, what happens if the ground is lost at the pole? Like any vandal could go there and cut it (probably get a nice arc flash in the face in the process)
We had this happen around where I live (NW Ontario). We had about 2 or 3 days of intermittent power failures, lots of flickers, and many blown transformers. They stole the copper of a bunch of rural towers and after a thunder/wind storm the city lost power in a bunch of areas. It was really strange as it seemed to effect only certain transformers whereas most outages are entire areas. Your neighbor would have power, but you wouldn't.

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