Main disconnect on building for 2020?

JoeNorm

Senior Member
I was talking to an inspector from my area yesterday and he mentioned there may be a new requirement to have a main service disco on the residence(outside, on side of building) for 2020. Presumably for first response reasons but I don't know for sure. Anyone know more about this?
 

PaulMmn

Senior Member
Not a bad idea, as long as the breaker box is inside, out of the weather! Keep those AFCIs and GFCIs nice and dry.
 

Dennis Alwon

Moderator
Staff member
Not a bad idea, as long as the breaker box is inside, out of the weather! Keep those AFCIs and GFCIs nice and dry.
If the box was inside then there would be no reason for this section. It requires the diso outside.

230.85 Emergency Disconnects(s)
For one- and two-family dwelling units, all service conductors shall terminate in disconnecting means having a short-circuit rating equal to or greater than the available fault current, installed in a readily accessible outdoor location. If more than one disconnect is provided, they shall be grouped. Each disconnect shall be one of the following:

(1) Service disconnect(s) marked as follows: EMERGENCY DISCONNECT, SERVICE DISCONNECT

(2) Meter disconnect(s) installed per 230.83(#) and marked as follows: EMERGENCY DISCONNECT, METER DISCONNECT, NOT SERVICE EQUIPMENT

(3) Other than listed disconnect switch(es) or circuit breaker(s) on the supply side of each service disconnect that are suitable for use as service equipment and marked : EMERGENCY DISCONNECT, NOT SERVICE EQUIPMENT

Markings shall comply with 110.21(B)
 

PaulMmn

Senior Member
If the box was inside then there would be no reason for this section. It requires the diso outside.
I'm talking about the box with all the branch breakers, not the main disconnect. Outside, you've got the meter, and one big switch to cut off all power to the building. That's it. Keep the branch breakers (in their box) inside where it's dry!
 

Dennis Alwon

Moderator
Staff member
I'm talking about the box with all the branch breakers, not the main disconnect. Outside, you've got the meter, and one big switch to cut off all power to the building. That's it. Keep the branch breakers (in their box) inside where it's dry!
Gotcha--- more money that way but I agree it is probably a better job
 

romex jockey

Senior Member
One local poco's recent policy is to install cutouts on the serving pole on my turf

If one thinks on it, most serious fires end up having the poco disco the service at the pole anyways

~RJ~
 

kwired

Electron manager
One local poco's recent policy is to install cutouts on the serving pole on my turf

If one thinks on it, most serious fires end up having the poco disco the service at the pole anyways

~RJ~
But with disconnect that is accessible to fire fighters, they don't have to wait for POCO to know the power is off.

Finding said disconnect is another story. Even if on outside, property owners may still hide it to certain extent.
 

Buck Parrish

Senior Member
So if I'm wiring a new home. They want the inside panel in the garage exactly behind the meter. Are you saying I'd have to install a disconnect right behind the panel? Is that before the meter or on the HO side?
That would be significant if you do a lot of 400 amp services.
 

kwired

Electron manager
So if I'm wiring a new home. They want the inside panel in the garage exactly behind the meter. Are you saying I'd have to install a disconnect right behind the panel? Is that before the meter or on the HO side?
That would be significant if you do a lot of 400 amp services.
Might as well plan to put service disconnect outside and maybe use main lug panel inside. Though it doesn't require the service disconnect to be outside, just an emergency disconnect to be outside.

See section content Dennis posted in post 4.

Note it does not say it has to be on the dwelling either just "installed in a readily accessible outdoor location." I see potential changes for clarification coming in the next code.
 

Dennis Alwon

Moderator
Staff member
So if I'm wiring a new home. They want the inside panel in the garage exactly behind the meter. Are you saying I'd have to install a disconnect right behind the panel? Is that before the meter or on the HO side?
That would be significant if you do a lot of 400 amp services.
Right now you don't have to worry but if NC accepts this section with no amendments then you will need either 1- 400 amp disconnect next to the meter or 2- 200 amp discos next to the meter before you go inside to the sub panels.

I am not sure what an emergency disconnect is considered if not part of the service equipment. A disconnect before the meter???
 

kwired

Electron manager
Right now you don't have to worry but if NC accepts this section with no amendments then you will need either 1- 400 amp disconnect next to the meter or 2- 200 amp discos next to the meter before you go inside to the sub panels.

I am not sure what an emergency disconnect is considered if not part of the service equipment. A disconnect before the meter???
That is why I see potential changes for clarification in next code. Too vague from what I am seeing and contradicting to previous existing requirements of art 230. Generally first switch needed to be the service disconnecting means, then they apparently now want this switch but as worded doesn't necessarily need to be the service disconnect.

Apparently a "meter disconnect switch" required by some POCO's (though many of those are not on a dwelling but rather on 200 amp and less 480 volt applications) would be allowed to be considered serving this purpose, and yet still require an additional service disconnect.
 

ron

Senior Member
It will be interesting if breakers installed outside in cold environments will experience higher trip values, and how the AHJ will relate it to downstream wire size protection.
 

jim dungar

Moderator
Staff member
It will be interesting if breakers installed outside in cold environments will experience higher trip values, and how the AHJ will relate it to downstream wire size protection.
In cold environments, thermal magnetic breakers will carry more current, is that what you are referring to? But for the most part the 'up North here' nobody takes the characteristics into consideration. There are thousands of multi-metering applications installed where no adjustments have been required.


The emergency disconnect, like the meter disconnect, probably would not need to be rated to close into a fault condition, and may not even need to break bolted fault conditions, unlike a service disconnecting means.
 

ron

Senior Member
In cold environments, thermal magnetic breakers will carry more current, is that what you are referring to? But for the most part the 'up North here' nobody takes the characteristics into consideration. There are thousands of multi-metering applications installed where no adjustments have been required.


The emergency disconnect, like the meter disconnect, probably would not need to be rated to close into a fault condition, and may not even need to break bolted fault conditions, unlike a service disconnecting means.
That is what I was thinking of.
I think most folks will use the emergency disconnect as the service disconnect whenever possible.
 

JoeNorm

Senior Member
In my area(rural area) all of our meters are placed by the transformers, wherever they may be. Usually somewhere along the main road. For the last 10 years or so our utility has required a main disconnect out there along with the meter for any major modification or new construction. I am guessing we are already satisfying the new requirement by doing it this way.
 

kwired

Electron manager
In my area(rural area) all of our meters are placed by the transformers, wherever they may be. Usually somewhere along the main road. For the last 10 years or so our utility has required a main disconnect out there along with the meter for any major modification or new construction. I am guessing we are already satisfying the new requirement by doing it this way.
Same thing with most rural services around here, particularly 400 amp and less single phase. Three phase usually 200 amp or less and sometimes 400 amps.

NEC is pretty vague on where this emergency disconnect must be located. I can see future changes possibly coming to tell us it needs to be on the building or maybe something like within 30 or 50 feet.
 

ggunn

PE (Electrical), NABCEP certified
Here in Austin the AHJ has had the requirement for an external service disconnect for many years. Under "you touch it, you fix it" we have to install one if it's not there any time we add a PV system to a residence, even if it lands on a backfed breaker in the MDP.
 
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