I have a Stepdown transformer 277/480 to 120/208 located directly adjacent to the utility TX. this was installed to supply the correct voltage to an existing service in a C store. the utility changed from pole mounted tansformers. to the new ground mounted TX. to supply a building requiring 277/480. What are the secondary conductors from the step down TX. (existing service conductors)now considered
Transformer secondaries
- Thread starter pfarr
- Start date
- Status
- Location
- Massachusetts
Re: Transformer secondaries
I have to imagine there is a fused disconnect switch between the utility's transformer and the customers transformer.
If there is, this would be the service disconnect and any thing on the load side would be feeders.
If this Feeder is now feeding what used to be service entrance conductors, you will need to remove the bonding in the old service disconnect.
Anyway thats how I see it.
Bob
Where is the service disconnect in relation to these conductors?
I have to imagine there is a fused disconnect switch between the utility's transformer and the customers transformer.
If there is, this would be the service disconnect and any thing on the load side would be feeders.
If this Feeder is now feeding what used to be service entrance conductors, you will need to remove the bonding in the old service disconnect.
Anyway thats how I see it.
Bob
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Transformer secondaries
Separately Derived System.
A premises wiring system whose power is derived from a battery, from a solar photovoltaic system, or from a generator, transformer , or converter windings, and that has no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system .
Only if there is no grounded conductor or grounding conductor that is connected accross the transformer from neutral to neutral.
Separately Derived System.
A premises wiring system whose power is derived from a battery, from a solar photovoltaic system, or from a generator, transformer , or converter windings, and that has no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system .
hbendillo
Senior Member
- Location
- South carolina
Re: Transformer secondaries
pfarr, did you get your question answered because I sure am confused as to what you are asking? If the utility changed from pole to pad mounted transformer(s), how does the original step down transformer now get fed? I see no change if you simply have to refeed the stepdown from the new transformer.
pfarr, did you get your question answered because I sure am confused as to what you are asking? If the utility changed from pole to pad mounted transformer(s), how does the original step down transformer now get fed? I see no change if you simply have to refeed the stepdown from the new transformer.
- Location
- Illinois
- Occupation
- retired electrician
Re: Transformer secondaries
Wayne,
Wayne,
Code Making Panel 1 does not agree with your statement. A connection of a common grounding conductor is not a direct conenction to a circuit conductor. Look at the panel comment in the proposal shown below.
Don
Re: Transformer secondaries
Don: I know we have kicked this dead horse for a long time.
The code making panel is completely in error, and I will post a $10,000 bond payable to the NFPA, if they can prove their opinion is correct. I also expect reciprocation.
It is such crap like this that confuses the new people in the trade.
I will pay my own cost to meet with any of them and debate this issue, with three registered engineers as proctors. I lose, I pay the expert witnesses, they lose, they pay.
Don: I know we have kicked this dead horse for a long time.
The code making panel is completely in error, and I will post a $10,000 bond payable to the NFPA, if they can prove their opinion is correct. I also expect reciprocation.
It is such crap like this that confuses the new people in the trade.
I will pay my own cost to meet with any of them and debate this issue, with three registered engineers as proctors. I lose, I pay the expert witnesses, they lose, they pay.
Re: Transformer secondaries
Don,
this is proof that not all (unlike our Charlie E ) panel members are sane people, and in fact they are downright scary.
In otherwords if they are going to spend such time and effort to perfect grounding, and then these same people do not realize all grounding and associated bonding conductors are "direct electrical connections", we are definately in trouble and are being led by the blind.
Roger
Don,
( see Don's post above)
this is proof that not all (unlike our Charlie E ) panel members are sane people, and in fact they are downright scary.
In otherwords if they are going to spend such time and effort to perfect grounding, and then these same people do not realize all grounding and associated bonding conductors are "direct electrical connections", we are definately in trouble and are being led by the blind.
Roger
Re: Transformer secondaries
So many technical books have been written by ill informed code experts that to correct this flagrant error will trash a lot of books and careers.
This error must be corrected and the panel dismissed for incompetance, or the NEC will lose what is left of its credibility.
I have plenty of engineering documentation that proves beyond a doubt, that the panel members are full of bull.
The persons in this trade deserve a better representation of facts.
[ January 07, 2004, 11:42 PM: Message edited by: bennie ]
So many technical books have been written by ill informed code experts that to correct this flagrant error will trash a lot of books and careers.
This error must be corrected and the panel dismissed for incompetance, or the NEC will lose what is left of its credibility.
I have plenty of engineering documentation that proves beyond a doubt, that the panel members are full of bull.
The persons in this trade deserve a better representation of facts.
[ January 07, 2004, 11:42 PM: Message edited by: bennie ]
Re: Transformer secondaries
Anyone who wants to prove me wrong, draw a schematic of a MGN distribution system and a premises transformer called a separately derived system, and show me the difference. Show me the premises trsnsformer is not electrically connected to the distribution system. If this is not I will donate the $10 grand to the NFPA.
I am real concerned with the direction of the trade, when the code officials make such stupid statements. I sure hope they read this.
Anyone who wants to prove me wrong, draw a schematic of a MGN distribution system and a premises transformer called a separately derived system, and show me the difference. Show me the premises trsnsformer is not electrically connected to the distribution system. If this is not I will donate the $10 grand to the NFPA.
I am real concerned with the direction of the trade, when the code officials make such stupid statements. I sure hope they read this.
scott thompson
Senior Member
- Location
- Anaheim, California
Re: Transformer secondaries
It blows me away too!
Even the most simple minded Chimpanzee can see that a Conductive Metallic item will do just that when connected to a Circuit - Conduct Electricity!!!
No matter which way it's tooled, the fact still remains:
* There _IS_ A Direct Electrical Connection between Primary and Secondary - and to me this very "Autotransformer-ish" now!
It will never be possible to claim - or draw a Schematic showing, solidly Grounded systems in a Structure not being directly and Physically Connected - when each system bonds to Metallic bodies (water pipes, structural steel, etc.).
Use a Typical 480Y/277 VAC 3?4W Service at a structure, then Ground it.
Star Point is Grounded, and Common Grounded Conductor runs out from Transformer Coils' Star Point.
Install a 480VAC Pri. ? 208Y/120VAC 3?4W Isolated Transformer - as usually done for 120V Power, and Ground it.
Star Point is once again Grounded, and Common Grounded Conductor runs out from Transformer Coils' Star Point.
Each of the Secondaries will also be bonded to any Metallic pipes or Structural items.
If this does not result in a direct connection of ACTIVE CIRCUIT CONDUCTORS, then please tell me whaddaheck am I doing in this Industry, fooling myself and others into thinking I have a shred of knowledge about Electrophysics!?!?!?
Yes they are Grounded, but so what! There's going to be a Potential Difference between the two Star Points, so what keeps this from resulting in a flow of Current?
As mentioned before, this is one of the Deadest Horses in Cyberspace!
Hot Files are still glowing from Months, and Years ago!
The funny thing is, if a Simpleton like Me can see it, why doesn't the CMP also see it?
OK, with that being said, all that I am doing here is tossing out the same old story, which we all have run through threads here since the first forum began! (what was that, like in 1997 or 98?).
No alliance or ridicule towards anyone - only the never been answered question of ...
Justwhaddaheckisgoingonhere!!!
Scott35
p.s. - edits for better sentences structure - they ended up trunicated after pasting the text back into this message body!
Me...Scott
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This Message Was Sent From:
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E-Mail: adst@pacbell.net
http://www.setelectric.electrical-contractor.net
Always Look For This "Sigfile" Or One Similar.
----------------------------------------------
Definitions:
Control (CON-TROL) n.;
A Very Small Prisoner That Lives Under A Bridge.
Asset (*** -ETTE) n.;
A Little Donkey.
Ascot (*** -COTT) n.;
A Little Bed For Donkeys.
Naval Destroyer (NAYEE-VULE DEE-STROIE-EER) n.;
A Hula-Hoop With A Nail In It.
Trivia Question:
Q: What Makes The Tower Of Pisa Lean?
A: It Never Eats.
[ January 08, 2004, 01:06 AM: Message edited by: scott thompson ]
It blows me away too!
Even the most simple minded Chimpanzee can see that a Conductive Metallic item will do just that when connected to a Circuit - Conduct Electricity!!!
No matter which way it's tooled, the fact still remains:
* There _IS_ A Direct Electrical Connection between Primary and Secondary - and to me this very "Autotransformer-ish" now!
It will never be possible to claim - or draw a Schematic showing, solidly Grounded systems in a Structure not being directly and Physically Connected - when each system bonds to Metallic bodies (water pipes, structural steel, etc.).
Use a Typical 480Y/277 VAC 3?4W Service at a structure, then Ground it.
Star Point is Grounded, and Common Grounded Conductor runs out from Transformer Coils' Star Point.
Install a 480VAC Pri. ? 208Y/120VAC 3?4W Isolated Transformer - as usually done for 120V Power, and Ground it.
Star Point is once again Grounded, and Common Grounded Conductor runs out from Transformer Coils' Star Point.
Each of the Secondaries will also be bonded to any Metallic pipes or Structural items.
If this does not result in a direct connection of ACTIVE CIRCUIT CONDUCTORS, then please tell me whaddaheck am I doing in this Industry, fooling myself and others into thinking I have a shred of knowledge about Electrophysics!?!?!?
Yes they are Grounded, but so what! There's going to be a Potential Difference between the two Star Points, so what keeps this from resulting in a flow of Current?
As mentioned before, this is one of the Deadest Horses in Cyberspace!
Hot Files are still glowing from Months, and Years ago!
The funny thing is, if a Simpleton like Me can see it, why doesn't the CMP also see it?
OK, with that being said, all that I am doing here is tossing out the same old story, which we all have run through threads here since the first forum began! (what was that, like in 1997 or 98?).
No alliance or ridicule towards anyone - only the never been answered question of ...
Justwhaddaheckisgoingonhere!!!
Scott35
p.s. - edits for better sentences structure - they ended up trunicated after pasting the text back into this message body!
Me...Scott
--
This Message Was Sent From:
Scott E. Thompson / Thompson Electric
Via PC#5 (W/S P55C.LOC05.001)
E-Mail: adst@pacbell.net
http://www.setelectric.electrical-contractor.net
Always Look For This "Sigfile" Or One Similar.
----------------------------------------------
Definitions:
Control (CON-TROL) n.;
A Very Small Prisoner That Lives Under A Bridge.
Asset (*** -ETTE) n.;
A Little Donkey.
Ascot (*** -COTT) n.;
A Little Bed For Donkeys.
Naval Destroyer (NAYEE-VULE DEE-STROIE-EER) n.;
A Hula-Hoop With A Nail In It.
Trivia Question:
Q: What Makes The Tower Of Pisa Lean?
A: It Never Eats.
[ January 08, 2004, 01:06 AM: Message edited by: scott thompson ]
Re: Transformer secondaries
Scott: Yours and Rogers validation mean a lot to me. This issue has been a sore in my backside for a long time. We are all intelligent people and the NEC discription of a separately derived system is a slap in the face and an insult to the years of studying and training.
It is time to put and end to this false concept by inept individuals who think they can dictate technology.
There's others that feel the same as we do over this subject. I hope they now come forward and be counted. You will contribute to the important accuracy of the application of the trade activity.
Scott: Yours and Rogers validation mean a lot to me. This issue has been a sore in my backside for a long time. We are all intelligent people and the NEC discription of a separately derived system is a slap in the face and an insult to the years of studying and training.
It is time to put and end to this false concept by inept individuals who think they can dictate technology.
There's others that feel the same as we do over this subject. I hope they now come forward and be counted. You will contribute to the important accuracy of the application of the trade activity.
Re: Transformer secondaries
First off, do not take this for defending the definition, because I also think it needs work and have criticized it in the past, But…I think the key word to look at is DIRECT.
They are not saying there is no electrical connection, they are saying there is no direct electrical connection.
Take a 480/277V service with a 480V-208/120V distribution transformer.
There are no phase conductors or neutrals of the 480/277V system that are directly connected to the phase conductors or neutrals of the 208/120V system. They are indirectly connected via the grounding system.
We have to assume by “supply conductors” they mean hot and neutrals, and exclude grounds.
First off, do not take this for defending the definition, because I also think it needs work and have criticized it in the past, But…I think the key word to look at is DIRECT.
They are not saying there is no electrical connection, they are saying there is no direct electrical connection.
Take a 480/277V service with a 480V-208/120V distribution transformer.
There are no phase conductors or neutrals of the 480/277V system that are directly connected to the phase conductors or neutrals of the 208/120V system. They are indirectly connected via the grounding system.
We have to assume by “supply conductors” they mean hot and neutrals, and exclude grounds.
- Location
- Illinois
- Occupation
- retired electrician
Re: Transformer secondaries
First off the code writers have the right to say what their code means. You and I do not have that right. Their opinion is the only one that counts. We do have the right to try to make changes in the code.
Second, the intent of the rule is that it is an SDS as long as there is not a direct physical connection between a conductor that normally carries current in each system(circuit conductor). The grounding conductor that ties the two grounded conductors is not a "circuit conductor". If you directly and physically connect the grounded conductors of the two systems to each other then it is not a SDS, but if you connect these same two conductors together via a grounding conductor it is a SDS. Does this make sense? Not really, but that is what the NFPA says the code means. Again, they have the right to define what any term used in the code means.
Don
[ January 08, 2004, 10:59 AM: Message edited by: don_resqcapt19 ]
First off the code writers have the right to say what their code means. You and I do not have that right. Their opinion is the only one that counts. We do have the right to try to make changes in the code.
Second, the intent of the rule is that it is an SDS as long as there is not a direct physical connection between a conductor that normally carries current in each system(circuit conductor). The grounding conductor that ties the two grounded conductors is not a "circuit conductor". If you directly and physically connect the grounded conductors of the two systems to each other then it is not a SDS, but if you connect these same two conductors together via a grounding conductor it is a SDS. Does this make sense? Not really, but that is what the NFPA says the code means. Again, they have the right to define what any term used in the code means.
Don
[ January 08, 2004, 10:59 AM: Message edited by: don_resqcapt19 ]
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