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#98852 - 06/17/06 10:01 PM 10-2 for a sub pabel?  
Trick440  Offline
Member
Joined: Aug 2005
Posts: 248
Waterford, MI, USA
A customer has a 10-2 circuit ran out to his shed.

Is there a legal way to turn this existing 10-2 circuit into a sub panel?

I thought awhile back I read a post where someone did something similar. And if I remember correctly the inspector failed it but it was legal by code.


Shake n Bake

2017 / 2014 NEC & Related Books and Study Guides

#98853 - 06/17/06 11:36 PM Re: 10-2 for a sub pabel?  
Larry Fine  Offline
Member
Joined: Feb 2005
Posts: 693
Richmond, VA
Well, yes and yes.

First would be to make it a 120v panel, jumping the hot to both lugs. Works fine as long as you don't need 240v. Wire as a sub-panel, with ground and neutral separated.

Second would be as a 240v. feed, using the bare as a combined neutral/EGC, as in the main panel, and the neutral/ground jumper used.

This requires no other conductive pathway (water pipe, coax-cable shield, etc.) between structures, as well as a driven ground at the shed.


Larry Fine
Fine Electric Co.
fineelectricco.com

#98854 - 06/18/06 01:27 AM Re: 10-2 for a sub pabel?  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,113
Estero,Fl,usa
Better hurry on option 2. I understand that method is going to dissapear in 2008.


Greg Fretwell

#98855 - 06/18/06 11:22 AM Re: 10-2 for a sub pabel?  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
Gfretwell, you are correct; the code comittee has accepted such a proposal. Comments are now being accepted.

Now, to be a little fussy about the idea....

Jumpering from one lug to another; well, make sure to replace the lug with one intended for two wires!

Now... 10-2 as a feeder. Doing load calcs at 3 watts / sq ft, you have plenty of capacity for almost any residential garage that is used as a garage.
There's the rub! In my cynical view of things, sub-panel = garage being converted to somethng else.
If they're planning to make a little apartment, they'll need 100 amps, not 30.
If they're planning to make it a workshop, you'll have to do further load calcs.


The advantages of another wire are immense. Indeed, I'd rather see 14-3 than 10-2!

Now.... how is the wire geting out to the garage? If this is a detached garage, romex is out, as it's not suitable for the application. UF is possible.
I am biased in favor of pipe. If I were doing this, I would run a vastly oversized pipe- at least 1" PVC. I'd also bury it DEEP- at least 2 ft. Call me paranoid. The larger pipe makes it easy to run larger wires later, and the cost increase is minimal.

Oh, and last (but not least)... you'll want a disconnect switch on the outside of a detached garage.


#98856 - 06/18/06 12:32 PM Re: 10-2 for a sub pabel?  
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
Reno- I question wether or not you'd need 100a. for an apartment. Based on the definition of an apartment found in Websters. As for the disconnect, it could be a 30a if the load did not exceed 2 circuits. If it were more than 2 circuits it would need to be probably 60a. See 225.39 Also should be SUSE rated. See 225.36. As for location it could be either inside or outside the building. See 225.32


George Little

#98857 - 06/18/06 02:54 PM Re: 10-2 for a sub pabel?  
Larry Fine  Offline
Member
Joined: Feb 2005
Posts: 693
Richmond, VA
Reno, a wire-nutted pair of pigtails would also suffice, no?


Larry Fine
Fine Electric Co.
fineelectricco.com

#98858 - 06/18/06 03:09 PM Re: 10-2 for a sub pabel?  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
Larry, I am uncomfortable with the use of wire nuts on a feeder. I tend to think of 'feeders' along the same lines as 'services,' and would prefer not to have such a splice... even if it is technically 'legal.' Mabye I'd feel better about using NSI's.
Oh, and kudos for reminding us that a panel would mean a ground rod was required!

George, I seem to recall the code specifying a minimum 100 amp service to each "residence". That would mean 100 amps per apartment.

The main point of my earlier post was to underline the need to be clear as to exactly what the intended purpose of the sub-panel was. All too often, I've seen folks try to "finesse" things, and be unhappy with the result. Might as well do it right to begin with!

[This message has been edited by renosteinke (edited 06-18-2006).]


#98859 - 06/18/06 03:59 PM Re: 10-2 for a sub pabel?  
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
Reno- I'm having trouble accepting your statment

Quote
George, I seem to recall the code specifying a minimum 100 amp service to each "residence". That would mean 100 amps per apartment.


I don't see where you need a 100a disconnect for an apartment and I'm looking in the code and all I find is the need for 100a disconnect for a "One-Family Dwelling".

Apartments are a different type of dwelling and are part of a multifamily building.


George Little

#98860 - 06/18/06 05:10 PM Re: 10-2 for a sub pabel?  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
We are talking about a separate structure, aren't we? I cannot see how, if converted into a residence, this would be anything but a "single family" residence, or more! I don't see how it could be called 'part' of the main residence.

Perhaps that distinction would hold, were we talking about converting an attached garage into a dwelling. But, in this case, the separation is a major factor.

I will admit that my first post, describing how I would like the job done, went beyond 'code minimums.' Some of this is preference; some of it is response to my not knowing just what the shed will be used for.

We have a practical sort of "catch 22" here. Almost any use of the shed, as a shed, can be quite nicely served by a single multi-wire circuit. Almost any other use, requiring a panel with multiple circuits, is going to need more than what 10-2 can deliver.


#98861 - 06/18/06 05:39 PM Re: 10-2 for a sub pabel?  
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
I guess I was hung up on your use of the word "apartment" and didn't want people assuming that apartments require 100a. feeders automaticly. The examples in the back of the book kinda show that. Interestingly enough if it is a single family dwelling supplied by a "Service" it must have minumum 100a Service Disconnect and 100a. Service conductors feeding it. After the Service disconnect if you were using fuses, you could use smaller fuses and conductors if they were adaquate to supply the load. 230.79

If the single family dwelling (not an apartment) is fed with a feeder instead of a Service the Disconnect must be 100a and the conductors feeding it only need to be large enough to supply the load and be potected at their ampacity. 225 39


George Little

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