10ft. tap rule..
- Thread starter herndon
- Start date
- Status
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
Re: 10ft. tap rule..
Wouldn't a tap terminating at a MLO panel with 42 circuits violate the requirement of a maximum of 6 circuits without a main disconnecting means?
- Location
- Massachusetts
Re: 10ft. tap rule..
No.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: 10ft. tap rule..
Bob is right. This would be a violation. 240.21 requires overcurrent protection at the point at which a conductor receives its supply. 240.21(B) gives exceptions, if the conductor is less than 10 feet long, and if you meet the remainder of the criteria. What you are describing does not meet that criteria.
{Edit: I didn't post fast enough. Now I have to say both Bob's are right.}
[ January 24, 2005, 12:46 PM: Message edited by: charlie b ]
Bob is right. This would be a violation. 240.21 requires overcurrent protection at the point at which a conductor receives its supply. 240.21(B) gives exceptions, if the conductor is less than 10 feet long, and if you meet the remainder of the criteria. What you are describing does not meet that criteria.
{Edit: I didn't post fast enough. Now I have to say both Bob's are right.}
[ January 24, 2005, 12:46 PM: Message edited by: charlie b ]
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
Re: 10ft. tap rule..
I'm not sure that the feeder breaker can feed both other loads and the MLO panel.
This seems more likely to pass muster, however I think you still have to deal with the rule of 6.
I'm not sure that the feeder breaker can feed both other loads and the MLO panel.
crossman
Senior Member
- Location
- Southeast Texas
Re: 10ft. tap rule..
The rule of six that I know is for services.
I am thinking this one is okay acording to the 10 foot tap rule.
[ January 24, 2005, 01:28 PM: Message edited by: crossman ]
The rule of six that I know is for services.
I am thinking this one is okay acording to the 10 foot tap rule.
[ January 24, 2005, 01:28 PM: Message edited by: crossman ]
Re: 10ft. tap rule..
I agree with crossman and engy that this might be OK for a power panel.
It would have to satisfy 240.21(B)(1)(1)(b) (in the 2002 NEC). To me that means you need a 225 amp tap for a 225A panelboard. But I could see easily see others interperting part (b) diffenently.
Steve
I agree with crossman and engy that this might be OK for a power panel.
It would have to satisfy 240.21(B)(1)(1)(b) (in the 2002 NEC). To me that means you need a 225 amp tap for a 225A panelboard. But I could see easily see others interperting part (b) diffenently.
Steve
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: 10ft. tap rule..
The answer is dependent on the type of panel.
First check if panels are protected.
No - 408.36(A) - lighting and appliance panel always require main devices.
Maybe - 408.36(B) - some power panels with neutrals may require main devices.
Yes - 408.36(B) exception - service panels with not more than 6 devices per 230.71 (but if it is a service panel than the tap rules of 240.21(B) definitely do not apply, but those of 240.21(C) might).
Second look at tap rule requirements
Maybe - 240.21(B)(1)(b) - refers to the rating of a single device OR a single overcurrent protective device. You may get away with calling a panelboard a device but then you need to go back to 408.36.
The answer is dependent on the type of panel.
First check if panels are protected.
No - 408.36(A) - lighting and appliance panel always require main devices.
Maybe - 408.36(B) - some power panels with neutrals may require main devices.
Yes - 408.36(B) exception - service panels with not more than 6 devices per 230.71 (but if it is a service panel than the tap rules of 240.21(B) definitely do not apply, but those of 240.21(C) might).
Second look at tap rule requirements
Maybe - 240.21(B)(1)(b) - refers to the rating of a single device OR a single overcurrent protective device. You may get away with calling a panelboard a device but then you need to go back to 408.36.
- Location
- Illinois
- Occupation
- retired electrician
Re: 10ft. tap rule..
Jim,
Don
Jim,
Lighting and appliance branch circuit panels do not require a "main". They require overcurrent protection on the line side. This is most often accomplished with a "main", but a line side OCPD exterior to the panel is permitted.
Don
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: 10ft. tap rule..
Don,
My use of the term main OCPD is not meant to imply it must be integral to the panelboard/device. I know of no reference in the NEC that any required OCPD be integral to any products.
Don,
My use of the term main OCPD is not meant to imply it must be integral to the panelboard/device. I know of no reference in the NEC that any required OCPD be integral to any products.
- Location
- Illinois
- Occupation
- retired electrician
Re: 10ft. tap rule..
Jim,
Sorry. I guess that there is some regional differences on the use of the term "main". In this area, the normal use, of the term means that there is a main breaker installed in the panlel itself. Maybe the use of the word "main" is not the same in your area. I just wanted to make it clear that the code only requires "supply side" protection.
Don
Jim,
Sorry. I guess that there is some regional differences on the use of the term "main". In this area, the normal use, of the term means that there is a main breaker installed in the panlel itself. Maybe the use of the word "main" is not the same in your area. I just wanted to make it clear that the code only requires "supply side" protection.
Don
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: 10ft. tap rule..
Don,
You are probably more universal in your definition than I in mine. Aren't regional colloquiums grand?
Don,
You are probably more universal in your definition than I in mine. Aren't regional colloquiums grand?
- Status