"main" breaker needed in subpanel?

[68Malibu383]

I've got a detached shop under construction at my residence and passed electrical rough-in and am just about ready for the final. Main panel on exterior house wall has six breakers (including one, 100 amp, for the shop) and there is a sub panel inside of the home.

The electrician said that I would likely need a main cutoff breaker inside of the shop sub panel, not just in the house main panel. I asked why and he said last time he wired a detached shop, the county made him install a main cutoff in the shop. He did not ask for a code reference or challenge the county, so I don't know their justification. I'm trying to get my ducks in a row in case they require me to do the same.

 

[jumper]

Look at 225.30 to 225.40.

 

[infinity]

Since it's detached a disconnect is required.

225.31 Disconnecting Means. Means shall be provided
for disconnecting all ungrounded conductors that supply or
pass through the building or structure.
225.32 Location. The disconnecting means shall be in-
stalled either inside or outside of the building or structure
served or where the conductors pass through the building or
structure. The disconnecting means shall be at a readily
accessible location nearest the point of entrance of the conductors. For the purposes of this section, the requirements
in 230.6 shall be utilized.
Exception No. 1: For installations under single management, where documented safe switching procedures are established and maintained for disconnection, and where the
installation is monitored by qualified individuals, the dis-
connecting means shall be permitted to be located else-
where on the premises.
Exception No. 2: For buildings or other structures qualifying under the provisions of Article 685, the disconnecting
means shall be permitted to be located elsewhere on the
premises.
Exception No. 3: For towers or poles used as lighting
standards, the disconnecting means shall be permitted to be
located elsewhere on the premises.
Exception No. 4: For poles or similar structures used only
for support of signs installed in accordance with Article
600, the disconnecting means shall be permitted to be located elsewhere on the premises.

 

[68Malibu383]

Since it's detached a disconnect is required.

Thanks for your help.

I guess it is required since, "The disconnecting means shall be at a readily
accessible location nearest the point of entrance of the conductors"

The current disconnect is inside of the house panel, which is not the nearest the point of entrance of the conductors.

Do you know if this is a recent change because I have seen hundreds of detached garages with the only disconnect inside of the panel attached to the home?

 

[jumper]

Thanks for your help.

I guess it is required since, "The disconnecting means shall be at a readily
accessible location nearest the point of entrance of the conductors"

The current disconnect is inside of the house panel, which is not the nearest the point of entrance of the conductors.

Do you know if this is a recent change because I have seen hundreds of detached garages with the only disconnect inside of the panel attached to the home?

Been code for quite awhile.

 

[electrofelon]

Do you know if this is a recent change because I have seen hundreds of detached garages with the only disconnect inside of the panel attached to the home?

I do not know when that requirement first appeared, but it is NOT a recent change.

Btw, if there are 6 or less branch breakers, you can use a service rated MLO panel without a single main, maybe that is what you have seen?

 

[charlie b]

It's not a recent change. But do keep in mind that what is needed is a way to disconnect power from the separate building, using a device (switch, breaker, or something else) "nearest the point of entrance." A main breaker on the sub panel is the simplest way to achieve that. Having only 6 breakers in an MLO panel would also work, as electrofelon has already pointed out. But an unfused disconnect switch on the outside wall, and an MLO panel with as many breakers as you wish, is also a compliant solution.

Please note as well that if you enter the building on one wall, and install the panel on the opposite wall, you might run afoul of the "nearest the point of entrance" requirement. Here in Washington State, you can't go more than 15 feet inside the building before hitting the main disconnect. Other states have even more strict requirements.

 

[necGuru]

It's not a recent change. It's been in the code for like...forever.

If you put a main breaker in the subpanel (back-fed) you will more than likely need some kind of retaining clip or screw to hold it down. This is also something that the "combination" inspector would probably miss. Read the inside of the subpanel door for the correct model number of the retaining clip, screw, or whatever may be required. Read the inside of the subpanel door (diagram) for where the main breaker is allowed to go.

Cheers!

 

[jumper]

It's not a recent change. It's been in the code for like...forever.

If you put a main breaker in the subpanel (back-fed) you will more than likely need some kind of retaining clip or screw to hold it down. This is also something that the "combination" inspector would probably miss. Read the inside of the subpanel door for the correct model number of the retaining clip, screw, or whatever may be required. Read the inside of the subpanel door (diagram) for where the main breaker is allowed to go.

Cheers!

More than likely? When would you not?

408.36

(D) Back-Fed Devices. Plug-in-type overcurrent protec- tion devices or plug-in type main lug assemblies that are backfed and used to terminate field-installed ungrounded supply conductors shall be secured in place by an addi- tional fastener that requires other than a pull to release the device from the mounting means on the panel.

 

[nizak]

There has never been enforcement of a disconnecting means located at an outbuilding in the local areas I work in?

2 pole 100 amp breaker from house panel feeds a main lug 20 space sub panel located in a detached pole building or garage.

Have seen it approved that way for 20 years with a number of different inspectors.

 

[jumper]

There has never been enforcement of a disconnecting means located at an outbuilding in the local areas I work in?

2 pole 100 amp breaker from house panel feeds a main lug 20 space sub panel located in a detached pole building or garage.

Have seen it approved that way for 20 years with a number of different inspectors.

And that makes it legal NEC wise? Nope.

 

[nizak]

Not saying it's legal.

I find it hard to believe it's never been enforced.

I'm guilty of the installs myself.

 

[jumper]

Not saying it's legal.

I find it hard to believe it's never been enforced.

I'm guilty of the installs myself.

Oh, sorry. I misinterpreted.:ashamed1:

 

[ggunn]

More than likely? When would you not?

When the backfed current comes from a utility interactive inverter.

 

[jumper]

When the backfed current comes from a utility interactive inverter.

From a what? Walmart carry those?

You solar dudes are just plain weird.

 

[GerryB]

Since it's detached a disconnect is required.

Why wouldn't excep 2 apply for a HO and a detached garage, shop, etc? Single management, (he lives there), documented safe switching procedures??, monitored by qualified individual, (again he lives there and it takes two minutes to show someone if they don't already know how to operate a circuit breaker.) How about a placard like the million the solar guys install, or more than one service to a building you need placards etc. As another said, seen a lot without a disco.

 

[electrofelon]

Why wouldn't excep 2 apply for a HO and a detached garage, shop, etc? Single management, (he lives there), documented safe switching procedures??, monitored by qualified individual, (again he lives there and it takes two minutes to show someone if they don't already know how to operate a circuit breaker.) How about a placard like the million the solar guys install, or more than one service to a building you need placards etc. As another said, seen a lot without a disco.

Not sure what exception 2 is you refer to........?
If you look at the article 100 definition of qualified person, I doubt a HO fits that.
I don't see any allowance for placecarding the disco location in this situation.

 

[jumper]

Why wouldn't excep 2 apply for a HO and a detached garage, shop, etc? Single management, (he lives there), documented safe switching procedures??, monitored by qualified individual, (again he lives there and it takes two minutes to show someone if they don't already know how to operate a circuit breaker.) How about a placard like the million the solar guys install, or more than one service to a building you need placards etc. As another said, seen a lot without a disco.

2 minutes? Anybody? :blink:

Qualified Person. One who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training to recognize and avoid the hazards involved.

 

[petersonra]

More than likely? When would you not?

408.36

(D) Back-Fed Devices. Plug-in-type overcurrent protec- tion devices or plug-in type main lug assemblies that are backfed and used to terminate field-installed ungrounded supply conductors shall be secured in place by an addi- tional fastener that requires other than a pull to release the device from the mounting means on the panel.

You would not need it if it was not a plug in style breaker. but they cost more and are not real common in residences.

 

[jumper]

You would not need it if it was not a plug in style breaker. but they cost more and are not real common in residences.

Yes, I know that........ that section I posted is for plug on breakers...and this thread is about a resi panel....