Reverse wired breaker oddity

Reply

  #1  
Old 12-28-06, 12:07 AM
Member
Thread Starter
Join Date: Jan 2005
Posts: 135
Reverse wired breaker oddity

I'm no electrician but I saw something strange today and would appreciate any insight. I may not be using the correct terms but I hope you can figure out what I mean.

4-unit building. Service entrance comes into a metal box (did not see inside) which feeds 4 meters. Beneath each meter is a subpanel with a 60 amp breaker (30 amp double pole).

The wires coming from the meter are connected to the breaker- I mean directly connected. The wires coming from the unit are connected to the hot and neutral busses.

Is this acceptable? I've always seen the wires coming from the unit (house) connected to the breaker, with the wires from the service entrance and meter connected to the busses of the subpanel.

All four of these subpanels are wired the same and have been working fine for years.

Thank you for any feedback.
 
Sponsored Links
  #2  
Old 12-28-06, 04:28 AM
Member
Join Date: Apr 2006
Location: New Bern, NC
Posts: 1,623
You would need to contact the breaker mfg to find out if these breakers are backfeed rated. Most are.
 
  #3  
Old 12-28-06, 06:37 AM
Member
Join Date: Sep 2002
Location: welland ontario
Posts: 5,677
FYI A double 30 amp breaker is a 30 amp breaker not a 60 amp breaker.
 
  #4  
Old 12-28-06, 09:19 AM
Member
Thread Starter
Join Date: Jan 2005
Posts: 135
jwhite,

Thanks for the suggestion. It's a Murray and I'm heading over to the supply house today to check it out.

joed,

I appreciate the clarification. Even though I enjoy learning about electrical, this is yet another reason that I leave the actual work to the pros.
 
  #5  
Old 12-28-06, 09:54 AM
Member
Join Date: Feb 2002
Location: port chester n y
Posts: 2,117
"4-unit building. Service entrance comes into a metal box (did not see inside) which feeds 4 meters. Beneath each meter is a subpanel with a 60 amp breaker (30 amp double pole). " ------

Where are these eqiptments located?---- "Outdoor" or "Indoor" ?





"The wires coming from the unit are connected to the hot and neutral busses." ---

This is permissible provided that the rating of the circuit-breaker does not exceed the rating of the Feeder Conductors that connect to the panel busses via the "Main Lugs"







I " I've always seen the wires ( Feeder Conductors) coming from the (dwelling unit ) connected to the breaker, with the wires from the service entrance and meter connected to the busses of the subpanel. "----

If the Service Conductors from the "Load" terminals of the meter-socket connect to the "Main Lugs" of a panel, the panel cannot be de-energized unless the meter is removed from the socket.

Also, if each panel can accomodate 2 or more breakers, and the Service Conductors supply 4 such panels thru "Main Lug" connections, if would be possible to connect 2 or more breakers in each panel directly to the Service Conductors, and each such breaker is a de facto "Service Dis-connect", which results in 2 or more Dis-connects-per- dwelling unit.
 
  #6  
Old 12-28-06, 07:12 PM
Member
Thread Starter
Join Date: Jan 2005
Posts: 135
PATTBAA,

Thank you very much for the additional information, and also for providing the correct terms to facilitate discussion.


Where are these eqiptments located?---- "Outdoor" or "Indoor" ?
They are outside but protected from the weather.


This is permissible provided that the rating of the circuit-breaker does not exceed the rating of the Feeder Conductors that connect to the panel busses via the "Main Lugs"
I believe the feeder conductors are 12g that go into a subpanel within the dwelling unit. This subpanel contains two 20amp breakers. So if the main circuit breaker is a 30amp double breaker, does this mean the rating is not exceeded?


If the Service Conductors from the "Load" terminals of the meter-socket connect to the "Main Lugs" of a panel, the panel cannot be de-energized unless the meter is removed from the socket.
I think I understand this. But what happens if there is no building shutoff/disconnect before between the service entrance and the meters? If you needed to change a breaker would you have to do it hot?

Also, if each panel can accomodate 2 or more breakers, and the Service Conductors supply 4 such panels thru "Main Lug" connections, if would be possible to connect 2 or more breakers in each panel directly to the Service Conductors, and each such breaker is a de facto "Service Dis-connect", which results in 2 or more Dis-connects-per- dwelling unit.
And if you have only one 30 amp double breaker in each panel, does that mean you have one de facto Service Dis-connect per dwelling unit?
 
  #7  
Old 12-29-06, 10:25 AM
Member
Join Date: Feb 2002
Location: port chester n y
Posts: 2,117
[QUOTE=findtheriver;1097876]PATTBAA,

Thank you very much for the additional information, and also for providing the correct terms to facilitate discussion.




They are outside but protected from the weather.




"I believe the feeder conductors are 12g that go into a subpanel within the dwelling unit. This subpanel contains two 20amp breakers. So if the main circuit breaker is a 30amp double breaker, does this mean the rating is not exceeded?"------

The minimum size Feeder to a dwelling-unit at one time was required to have an ampacity of 30, = #10 wire. A 30 CB protecting #12 conductors is a violation,----- Art 240.4 (D), Small Conductors




"But what happens if there is no building shutoff/disconnect before between the service entrance and the meters? If you needed to change a breaker would you have to do it hot?"-----

"Do it Hot?" --- A "Judgement Call" for reserved for experienced and well-qualified individuals ONLY. Such a person, if need be, could de-energize the Service by removing the utility connections , if the utility connection is in the form of an aerial cable.



"And if you have only one 30 amp double breaker in each panel, does that mean you have one de facto Service Dis-connect per dwelling unit?"-----

Yes, but it's possible a 2nd Feeder could be extended from the panel, presuming the panel could accomadate another CB. One possible consequence of connecting a 2nd Feeder is a Total Connected load with a current-value that that exceeds the ampacity of the Service Conductors (S-C's) that terminate on the lugs of the panel, a condition not possible when the S-C's from the meter terminate on a C-B which limits the Load-current to the ampacity of the S-C's.
 
  #8  
Old 12-29-06, 08:47 PM
Banned. Rule And/Or Policy Violation
Join Date: Feb 2006
Location: North of Boston, MA.
Posts: 2,113
4-unit building. Service entrance comes into a metal box (did not see inside) which feeds 4 meters. Beneath each meter is a subpanel with a 60 amp breaker (30 amp double pole).

The wires coming from the meter are connected to the breaker- I mean directly connected. The wires coming from the unit are connected to the hot and neutral busses. "

I would read this as:

Feed to the meter,Then tapped to each panel. Each panel with the 30A disconnect as the main.

Perhaps the OPs' previouse experience has been with main disconnect at the meter location.
JWhite may have hit it. Feed the breaker, then lug it to a sub panel in the unit. Whith branch ckts there. Sounds ok.
 
  #9  
Old 12-29-06, 10:20 PM
hornetd's Avatar
Member
Join Date: Aug 2001
Location: Maryland
Posts: 695
Are they panels or enclosures?

Are they panels or enclosures? If what you are calling a panel is a breaker enclosure for only one double pole breaker then it sounds weird that the service conductors are connected to the breakers terminals instead of to the main lugs of the buss. If it really is a panel cabinet then it is a rather unusual installation to say the least. Breakers that are back fed in that manner must be secured with a listed means that prevents accidental removal of the breaker from the buss bar while it is energized. Was there some sort of fastener present to hold these breakers onto the buss bar that could only be removed with tools?
--
Tom Horne
 
  #10  
Old 12-30-06, 10:38 AM
Member
Thread Starter
Join Date: Jan 2005
Posts: 135
PATTBAA,

Thanks again for the help.

You wrote:

"The minimum size Feeder to a dwelling-unit at one time was required to have an ampacity of 30, = #10 wire. A 30 CB protecting #12 conductors is a violation,----- Art 240.4 (D), Small Conductors"


I appreciate the citation. I wonder if such a condition is grandfathered in or presents such a dangerous situation as to require immediate upgrade and will talk with the building dept next week.


You wrote:

"'Do it Hot?' --- A 'Judgement Call' for reserved for experienced and well-qualified individuals ONLY. Such a person, if need be, could de-energize the Service by removing the utility connections , if the utility connection is in the form of an aerial cable."


Thanks for the advisement.

You wrote:

"Yes, but it's possible a 2nd Feeder could be extended from the panel, presuming the panel could accomadate another CB. One possible consequence of connecting a 2nd Feeder is a Total Connected load with a current-value that that exceeds the ampacity of the Service Conductors (S-C's) that terminate on the lugs of the panel, a condition not possible when the S-C's from the meter terminate on a C-B which limits the Load-current to the ampacity of the S-C's."


I don't think there's room for another CB. If I'm reading this correctly it sounds like there's a benefit (not being able to exceed the ampacity of the SC) if the SCs from the meter terminate on the CB instead of on the lugs.
 
  #11  
Old 12-30-06, 10:43 AM
Member
Thread Starter
Join Date: Jan 2005
Posts: 135
lectriclee,

Thanks for the feedback.

You wrote:

"I would read this as:

Feed to the meter,Then tapped to each panel. Each panel with the 30A disconnect as the main."


Yes, that seems to be exactly what I was trying to say. Nice concision.


You wrote:

"Perhaps the OPs' previouse experience has been with main disconnect at the meter location."


Spot-on again. This is precisely what I usually see and this new situation threw me a bit.


You wrote:

"JWhite may have hit it. Feed the breaker, then lug it to a sub panel in the unit. Whith branch ckts there. Sounds ok."

If the breaker wiring at the main panel is ok then the question becomes whether the 12g feeder conductors from the dwelling unit need to be replaced.
 
  #12  
Old 12-30-06, 10:48 AM
Member
Thread Starter
Join Date: Jan 2005
Posts: 135
Tom,

Thanks for the reply.

You wrote:

"Are they panels or enclosures? If what you are calling a panel is a breaker enclosure for only one double pole breaker then it sounds weird that the service conductors are connected to the breakers terminals instead of to the main lugs of the buss. If it really is a panel cabinet then it is a rather unusual installation to say the least."


A friend first pointed out the oddity and it does indeed seem unusual to me too. I'm going to take some photos because my poor and inaccurate description may be misleading.


You wrote:

"Breakers that are back fed in that manner must be secured with a listed means that prevents accidental removal of the breaker from the buss bar while it is energized. Was there some sort of fastener present to hold these breakers onto the buss bar that could only be removed with tools?"


I don't think so. The breaker pulled out just like any other.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes