Subpanel question

[sjaniga]

I have to install a 60-amp subpanel in a detached garage, the homeowner has indicated he will most likely want more than a six space panel, if I go larger than six spaces, do I need a main disconnect at the garage?

 

[dan55]

Re: Subpanel question

Yes, according to 225.33. I am not sure of the reasoning though.

 

[tom baker]

Re: Subpanel question

A feeder or service is limited to six disconnects. You can use a larger panel, say a 12 space main lug (its only a few $ more) backfeed a 60A breaker, just make sure you use a retainging clip. take the guts out of the panel to install the clip, its easier.

 

[joe tedesco]

Re: Subpanel question

Backfeeding must be cleary understood. According to the UL Directory the follwing is supplied for your review:

LINE-LOAD CONNECTIONS

Line and load markings on a circuit breaker are intended to limit connections thereto as marked.

See the 2002 NEC? also:

408.16 Overcurrent Protection.

(F) Back-Fed Devices. Plug-in-type overcurrent protection 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 additional fastener that requires other than a pull to release the device from the mounting means on the panel.

NFPA Courtesy Link: www.nfpa.org
National Electrical Code? and NEC? are Registered Trademarks of the National Fire Protection Association, Quincy, Massachusetts 02269.

 

[don_resqcapt19]

Re: Subpanel question

You are not requried to provide a main just because there is space for more than six breakers in the panel. As long as you only install six breakers, you are in complinace with the code rule. The inspector cannot red tag the installation based on something that might be changed in the future.
Don

 

[tom baker]

Re: Subpanel question

In our area if we install a panel with more than 6 spaces and no main, it results in a violation.

 

[don_resqcapt19]

Re: Subpanel question

Tom,
I can't see how that violation can be upheld. If there are only 6 breakers at the time of inspection, there is no violation. If you install a 400 amp fusible disconnect with 225 amp fuses and wire, is it a violation just because you could easily put 400 amp fuses in the circuit? You cannot red tag for "possible future" violations.
Don

 

[hienlam]

Re: Subpanel question

there is no need for main breaker in sub-panel...
as long as your feeding panel has a main breaker or disconnect switch...

 

[sjaniga]

Re: Subpanel question

We ended up installing a 16 space panel,with a backfed 60-amp breaker with a retaining clip, inspector said it had to have a main becuase there were more than six spaces even though we only installed two circuits for lighting and GP receptacles, no sense in arguing, just did it.
Thanks for the replies.

 

[tom baker]

Re: Subpanel question

Don and all:
Four answers to a code question:
1. Code answer
2. AHJ answer
3. Toms answer
4. Truck answer.

 

[steve65]

Re: Subpanel question

if the panel that is feeding the sub panel has a 60 amp breaker going to the subpanel I don not see where the sub panel would need a main. I do mostly commerical work and I have installed many subpanels without a main as long as the panel feeding the subpanel has the proper breaker size.

 

[iwire]

Re: Subpanel question

Originally posted by steve65:
if the panel that is feeding the sub panel has a 60 amp breaker going to the subpanel I don not see where the sub panel would need a main.

I do the same all the time Steve, the difference here is the subpanel is in a detached garage and 225.33 require no more than six disconnects, this does not have to be an overcurrent device.

 

[Guest]

Re: Subpanel question

I believe the 6-handle rule applies to the MAIN panel only. Your MAIN panel cannot have more than 6-handles without having a MAIN breaker.

It is my understanding that a <6-handle MAIN panel can serve a SUBPANEL of any number of handles. Of course one of the 6-handles in the MAIN panel must serve the SUBPANEL. In that case there would be no need for a master backfed breaker in the SUBPANEL.

It is my further understanding that you cannot put a MAIN breaker in a SUBPANEL. You can have a MASTER breaker in a SUBPANEL, but by definition a MAIN braker must reside in a MAIN panel. If you have a <6-handle MAIN panel without a MAIN breaker, putting a MASTER breaker in the SUBPANEL would not make that backfed MASTER breaker a MAIN breaker.

A MAIN breaker is a breaker that will disconnect ALL power from the premise or dwelling.

That's my story, and I'm sticking to it

 

[dan55]

Re: Subpanel question

Art.225.33 applies to outside branch circuits and feeders, the conductors feeding the subpanel in the detached garage would be the feeders. If there are more than six throws than you will need a "main breaker" or "master breaker".

 

[iwire]

Re: Subpanel question

The six disconnect rule applies to a service or feeders to a second building fed from another.

ARTICLE 225 Outside Branch Circuits and Feeders
II. More Than One Building or Other Structure

225.31 Disconnecting Means.
Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure.

225.33 Maximum Number of Disconnects.
(A) General. The disconnecting means for each supply permitted by 225.30 shall consist of not more than six switches or six circuit breakers mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard. There shall be no more than six disconnects per supply grouped in any one location.

(B) Single-Pole Units. Two or three single-pole switches or breakers capable of individual operation shall be permitted on multiwire circuits, one pole for each ungrounded conductor, as one multipole disconnect, provided they are equipped with handle ties or a master handle to disconnect all ungrounded conductors with no more than six operations of the hand.

Also you need to install a ground rod for this second building.

250.32 Two or More Buildings or Structures Supplied from a Common Service.

(A) Grounding Electrode. Where two or more buildings or structures are supplied from a common ac service by a feeder(s) or branch circuit(s), the grounding electrode(s) required in Part III of this article at each building or structure shall be connected in the manner specified in 250.32(B) or (C). Where there are no existing grounding electrodes, the grounding electrode(s) required in Part III of this article shall be installed.

 

[dan55]

Re: Subpanel question

I should used the word disconnect instead of breaker because as stated before this case would not require the additional overcurrent protection just disconnecting means.

 

[jason]

Re: Subpanel question

Let me clarify something here. This is something I have run into lately and not something I practice. I've seen a couple of new houses with an outside disconnect feeding an inside panel. The inside panel has no main breaker. If I must have an outside disconnect, I always use a main breaker panel. In regards to what I am seeing, is this legal? If so I would say it's not good practice. But, if its legal I guess it's ok.

 

[iwire]

Re: Subpanel question

230.70 Allows the service disconnect outside or inside and 406.16 does not specify the supply side location of the required overcurrent protection.

So yes, you can have the service disconnect and overcurrent protection outside, and use a main lug panel inside.

230.70 General.
Means shall be provided to disconnect all conductors in a building or other structure from the service-entrance conductors.
(A) Location. The service disconnecting means shall be installed in accordance with 230.70(A)(1), (2), and (3).

(1) Readily Accessible Location.
The service disconnecting means shall be installed at a readily accessible location either outside of a building or structure or inside nearest the point of entrance of the service conductors.

408.16 Overcurrent Protection.
(A) Lighting and Appliance Branch-Circuit Panelboard Individually Protected.
Each lighting and appliance branch-circuit panelboard shall be individually protected on the supply side by not more than two main circuit breakers or two sets of fuses having a combined rating not greater than that of the panelboard.

 

[Guest]

Re: Subpanel question

OK, you're right. I missed the detached part. A detached building falls under the 6-handle rule.

Here are some other details that might help the DIY:

California Electrical Code

It's not the NEC, but it seems to parrott the NEC, and it puts the relevant stuff on one page.

 

[dan55]

Re: Subpanel question

Any body know the thought process on the 6 throw rule in 225.33. Why six. Also another good point brought up in this thread is you might have a detached garage 10 feet from a house that has more than six breakers so a disconnect is required but you can have a subpanel in the same house but could be 150 feet away with no disconnect.