10 foot rule for disconnect

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Stevenfyeager

Senior Member
Location
United States, Indiana
Occupation
electrical contractor
Does the 10 foot rule requiring an outside disconnect for a residential service panel (more than10 foot from the meter) mean 10 feet of conductors or 10 feet of distance between the meter and service panel? I've heard some differing opinions. Thank you
 

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
Is this a local rule? It is not an NEC requirement.

Roger
 

Carultch

Senior Member
Location
Massachusetts
Does the 10 foot rule requiring an outside disconnect for a residential service panel (more than10 foot from the meter) mean 10 feet of conductors or 10 feet of distance between the meter and service panel? I've heard some differing opinions. Thank you

Is this a utility requirement? Or is it a particular NEC requirement (please cite if you can)?

If we are talking a rule similar to the 10 ft tap rule in 240.21(B)(1), that is a case where it is the length of the conductor. The intent is to limit the distance that fault currents would propagate.

If we are talking about a utility's requirement to group the equipment, then it is probably the distance between enclosures, no matter how serpentine the conductors may be. Another unknown is whether it is 10 ft of distance you can walk, or 10 ft which can pass through a wall.
 

pkelectrical

Member
Location
NJ
Does the 10 foot rule requiring an outside disconnect for a residential service panel (more than10 foot from the meter) mean 10 feet of conductors or 10 feet of distance between the meter and service panel? I've heard some differing opinions. Thank you

You talking about a scenario when you have meter outside and lets say a breaker panel in the basement. You then have few feet of unprotected feeder entrance conductors going from the meter to the breaker panel.
Never heard of 10 foot rule. In NJ it is usually 2-3 feet, but it is nowhere in the code. It is something that is just generally accepted in the state/county you live in.
I heard a story of inspector that made the contractor install a disconnect when it was 2.5 feet (he only allowed 2 feet). Couldn't really argue with him.
 

roger

Moderator
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Location
Fl
Occupation
Retired Electrician
It is if it is a supply side interconnection. See 705.31.

Austin Energy interprets it as 10' conductor length.

Uhuh, and what leads you to believe the OP's question is a 705 question?

Roger
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Does the 10 foot rule requiring an outside disconnect for a residential service panel (more than10 foot from the meter) mean 10 feet of conductors or 10 feet of distance between the meter and service panel? I've heard some differing opinions. Thank you

As stated there is not 10'rule in the NEC and also conductors run on the outside of the house can be of unlimited length. The NEC wants the length run into the structure limited and they use the language for the service disconnect to be "inside nearest the
point of entrance of the service conductors."
 

mivey

Senior Member
Could be either. AHJ rules. Common are panel must be directly behind meter, in the same stud space, or within some arbitrary footage before disconnect needed.

The futher away, the more likely chance of damage to unprotected conductor. People are not as likely to drill or deep nail into a space around panel or meter. Leaving that stud space is riskier.

However, I have even seen service conductor (ahead of meter) run all the way through an attic to the other side of the house. POCO no likey like dat.
 

robbietan

Senior Member
Location
Antipolo City
Does the 10 foot rule requiring an outside disconnect for a residential service panel (more than10 foot from the meter) mean 10 feet of conductors or 10 feet of distance between the meter and service panel? I've heard some differing opinions. Thank you

In our part of the world, the utility requires the service disconnect to be within 15 feet of the meter. something about "accessibility" during times when you have to trip the breaker during emergencies
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
The NEC requirement is that the service disconnect be outside or 'inside nearest the point of entrance'. I could see an AHJ interpreting 'nearest' as up to 10ft but that's just an interpretation.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
The NEC requirement is that the service disconnect be outside or 'inside nearest the point of entrance'. I could see an AHJ interpreting 'nearest' as up to 10ft but that's just an interpretation.
In the OP's question the disconnect is located outside so, "nearest point of entrance" doesn't come into play.

Roger
 

mivey

Senior Member
In the OP's question the disconnect is located outside so, "nearest point of entrance" doesn't come into play.

Roger
You don't know that just from the post. The disconnect may very well be the inside panel main breaker. OP did not specify which case he had, but wanted to know when the OD was required.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
You don't know that just from the post. The disconnect may very well be the inside panel main breaker. OP did not specify which case he had, but wanted to know when the OD was required.
You are correct, I didn't take time to actually read the OP's question again.

Roger
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
You don't know that just from the post. The disconnect may very well be the inside panel main breaker. OP did not specify which case he had, but wanted to know when the OD was required.
Installing PV in San Antonio, more than half the services we encounter have no service disco, just a meter and an MLO MDP. Some of these panels have 20-30 load beakers in them.
 

kwired

Electron manager
Location
NE Nebraska
Does the 10 foot rule requiring an outside disconnect for a residential service panel (more than10 foot from the meter) mean 10 feet of conductors or 10 feet of distance between the meter and service panel? I've heard some differing opinions. Thank you


Here the general rule is 5 feet of service conductor is permitted inside the building. You can encase the service cable or raceway in 2 inches of concrete though and it is still considered outside if you need more length within the structure.
 

Johnnybob

Senior Member
Location
Colville, WA
He is saying that you can have up to 10 feet of service conductor, and if you were to have more than that then you would need an outside disconnect. Sounds like he wants to avoid a OD. As mentioned, not a nec rule, but perhaps local rule or practice.

Ahh. I didn't read it correctly either:?!
 

Stevenfyeager

Senior Member
Location
United States, Indiana
Occupation
electrical contractor
My job ended up having using 4 feet of conductors. Conductors were in pvc for about 22 inches between the enclosures. The inspector (this was a new district for me) passed it without comment. I had some other questions about the old house and forgot to ask him his thinking on the 10 foot rule.
Thank YOU for all your input.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
My job ended up having using 4 feet of conductors. Conductors were in pvc for about 22 inches between the enclosures. The inspector (this was a new district for me) passed it without comment. I had some other questions about the old house and forgot to ask him his thinking on the 10 foot rule.
Thank YOU for all your input.

Glad you got it installed and passed inspection.
But (unless local requirement) there is no "10 foot rule"!
 
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