Electrical Upgrade - Older House (3)


  #1  
Old 06-17-02, 12:42 PM
vhende2000
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Question Electrical Upgrade - Older House (3)

In moving into an older (1950's) rental home, I've now discovered (since no one had informed me) that the power to the house actually comes into a mains box, with the main disconnect, inside an attached garage. This panel seems to be a upgraded service since it has a double breaker (2 50Amps) to a receptacle for a welder in the garage (not currently in use). The service to the house is double breakered (2 60Amps) and apparently goes directly to the panel (with no main house disconnect) in utility room of house. The meter box (and presumably the grounding bar(s), since it/they cannot be seen) is mounted on the outside of the garage opposite the mains box.

Question: the original panel box in the house is labeled as for only 100 AMP service and has slots for only 6 breakers. But dosen't the 2 60Amp double breakers in the Mains box in the garage inply that, in reality, 120 Amps are supplied to the house?

Question: the feeder wires coming into the house panel appear to be the original wiring. Currently there are only 5 breakers in use, all 15 Amp circuits. Most wiring is 2-wire romax (no ground wire). Should the 2 60Amp breakers in the Mains panel be replaced with 2 50Amp breakers?
 
  #2  
Old 06-17-02, 08:56 PM
Wgoodrich
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You are allowed up to 6 sweeps of the hand disconnects to be used as main breakers. However your six main breakers are in the same box and I am suspecting that the service entrance conductors serving that box is rated at one hundred amps. Your service entrance conductors must be sized in ampacity equal to the maximum total load of all the main breakers it serves. Right now if you have a service entrance conductor serving that box that is without a main breaker protecting that box then the service entrance conductor are truly rated 100 amps you are in violation of hte NEC. The service entrance conductors serving that main box must be equal to the total combined amp rating of the 6 main breakers it serves.

The second violation is that your total combined amp rating of the main breakers that are fed without an overcurrent device by that service entrance conductor exceeds that amp rating of that box as listed at 100 amps.

You need to contact your landlord. Remember you don't own this house as a renter. All you can do is three choices. Have the owner correct the violation of the NEC, call your local inspector and issue a concern for safety, neither of which is going to make you landlord happy, or move out and obviously this won't make the landlord happy either. Problem is you are dealing with a wiring design that does not meet the minimum safety standards and if that house overloads that service entrance conductor you are risking a fire in that building.

Be careful

Wg
 
  #3  
Old 06-19-02, 09:17 AM
Gary Tait
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I personally don't see anything wrong.

You do have a main on that panel, I would just
consider the breaker in the garage the main.

The 100A rating is 100/side, so it is ok to feed it with 60A/side,
cosidering the small handful of circuits on it.

Then again WG is a professional.
 
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Old 06-19-02, 10:17 AM
P
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vhende states; "the power comes into a "mains" box with the MAIN DIS-CONNECT"-----vhende should determine the rating of the Main Dis-connect. ------Service conductors terminate at the Main Dis-Connect.Any wiring on the Load side of the Service Dis-Connect is either Branch-Circuits or Feeders. vhende further states; "The Service (actualy Feeder) to the house is double-breakered (2-pole 60 amp) and goes directly to the panel(Main Lugs) in the utility room"---If my understanding is correct and this is a feeder to the utility room with conductors rated at 60 amp. protected by a 60 amp. breaker then vhende need not be concerned when he states: "the panel box in the house (utility room?) is labeled for only 100 amp servive".-------"does 2 60 amp breakers mean 120 amps are supplied to the house?"--No.-----"Should the two 60 amp breakers be re-placed with 50 amp breakers?"----No, you would reduce the power available to the utility panel.---Good Luck!!!
 
  #5  
Old 06-19-02, 11:36 PM
Wgoodrich
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If you have a 100 amp rated panel you can not exceed that 100 amp panel rating with more than 100 amps being used. 110.3.B requires you to use that panel as listed and labeled following the manufacturer's instructions. I really doubt that the manufacturer instructs you to install all main breakers in a main lug only panel with a total combined load beyond that 100 amp rating. Then the service entrance conductor has rules that apply. Check the following rule and handbook commentary. Then think did anyone perform a demand load calculation of this building to see if it is within the standards of 220 of the NEC?

230.23 Size and Rating.
(A) General. Conductors shall have sufficient ampacity to carry the current for the load as computed in accordance with Article 220 and shall have adequate mechanical strength.
HANDBOOK COMMENTARY;
When a load is added to any service, the installer must be aware of all existing loads. The potential for overloading the service conductors must be governed by installer responsibility and inspector awareness; they should not rely solely on the usual method of overcurrent protection. The serving electric utility should be alerted to whenever load is added to ensure that adequate power is available.


Hope this helps

Wg
 
  #6  
Old 06-25-02, 11:11 PM
pickynicky
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Answer to question 1: No.
Answer to question 2: No.
From my understanding the person is describing that he has a 60 amp main which is feeding a downstream subpanel. If the subpanel has a higher ampere rating than the main it is not a code violation.
 
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Old 06-28-02, 05:53 AM
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Originally posted by pickynicky
Answer to question 1: No.
Answer to question 2: No.
From my understanding the person is describing that he has a 60 amp main which is feeding a downstream subpanel. If the subpanel has a higher ampere rating than the main it is not a code violation.
What? Picky, are you saying it is okay to feed a 100 amp subpanel off a 60 amp main?? I don't get it.
 
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Old 06-28-02, 07:56 AM
J
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Yes, it's okay to feed a 100-amp subpanel off a 60-amp main. Of course, it's impossible to get 100 amps out of it, but that's not a safety issue. It's like having a 2-gallon bucket -- just because you have a 2-gallon bucket doesn't mean you have two gallons of water, but neither does it mean that you can't use it to carry one gallon of water.
 
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Old 06-28-02, 08:11 PM
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Originally posted by John Nelson
Yes, it's okay to feed a 100-amp subpanel off a 60-amp main. Of course, it's impossible to get 100 amps out of it, but that's not a safety issue. It's like having a 2-gallon bucket -- just because you have a 2-gallon bucket doesn't mean you have two gallons of water, but neither does it mean that you can't use it to carry one gallon of water.
Heh, guess that is a good way to put it. Seems I had this conversation with a guy at Lowe's once. I guess I was concerned someone in the future might overload the main by running to much off the sub.
 
 

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