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Old 02-14-2011, 07:38 AM   #1
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detached shed sub panel


someone installed a sub panel that does not have a disconect in my detached shed, and I want to correct this! this is what I currently have -200 amp main service in house
100 amp breaker feeding sub (way overkill for my needs in a 10x14 shed)
wire in conduit burried from house to shed
wire size ? its copper and huge, way larger than 6ga two conductors and neautral
100 amp main lug only no ground rod.

what I want to do is - install a 60 amp 220 breaker in the main (take out the 100 amp)
back feed a 60 amp breaker in the 100 amp rated sub panel as a disconect, which my sub is made to take and will leave me with 4 spaces to configure circuits from.
make sure neautral bar is not grounded to box
and drive a ground rod and ground to ground buss bar.

does this sound right?

what confuse me is can the disconect breaker in the sub be the same rateing as the breaker in the main service supplying the sub? or could I leave the 100 amp feed breaker (if I determine the wire size is right for 100 amp) and just backfeed the 60 amp disconect in the sub? seems to me this would work, am I right?

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Old 02-14-2011, 07:55 AM   #2
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detached shed sub panel


Everything you have will work fine. The breaker in the main panel feeding the subpanel must be sized for the feed cable and for any subpanel connected by lugs without its own breaker whichever is spec'ed for less. Nothing wrong with a subpanel with a higher rated breaker also protected by a lower rated breaker in the main panel. Nothing wrong with a subpanel with its own main breaker connected to a feed with a higher rated breaker..

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Last edited by AllanJ; 02-14-2011 at 08:00 AM.
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Old 02-14-2011, 08:15 AM   #3
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detached shed sub panel


remember the six handle rule. If the sub panel has six or fewer handles it counts as a disconnect.
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Old 02-14-2011, 08:45 AM   #4
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detached shed sub panel


If you only have two hots and a neutral feeding a panel in a detached building (no longer allowed by the way), then you must BOND the neutral to the enclosure. You are also required to drive a ground rod at the detached building.

If you only have six breakers, your disconnect requirements are met.

One problem you may have in using a 60A breaker is the existing wire may not fit the breaker terminal.
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Old 02-14-2011, 09:03 AM   #5
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Originally Posted by HouseHelper View Post
If you only have two hots and a neutral feeding a panel in a detached building (no longer allowed by the way), then you must BOND the neutral to the enclosure. You are also required to drive a ground rod at the detached building.

If you only have six breakers, your disconnect requirements are met.

One problem you may have in using a 60A breaker is the existing wire may not fit the breaker terminal.
what is the wire size range to fit a 60 amp 220 dubble pull tie breaker from square d homeline?
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Old 02-14-2011, 09:23 AM   #6
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Quote:
Originally Posted by HouseHelper View Post
If you only have two hots and a neutral feeding a panel in a detached building (no longer allowed by the way), then you must BOND the neutral to the enclosure. You are also required to drive a ground rod at the detached building.

If you only have six breakers, your disconnect requirements are met.

One problem you may have in using a 60A breaker is the existing wire may not fit the breaker terminal.
guess I forgot to type in that there is also a heavy ground cable running with the two conductors and neautral ( all seem to be same ga)

so I beleive I need the neautral isolated from ground?

sub lug panel is a 6 space which I will be useing 2 spaces for back feed 220 amp disconect breaker and 2 spaces for a 220 amp breaker for welder and 1 space for light circuit and last space for recptical circuit

what size wire and breaker do I need for a 220 arc (stick) lincoln welder,
have not aquired welder yet, but would like to have the wireing there for when I get it.
I am guessing 30 amp on 10 ga?
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Old 02-14-2011, 09:31 AM   #7
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detached shed sub panel


I think I finally woke up!

if I only have a 6 space lug panel, then I do not need a seperate disconect, because 6 space qualifies as a disconect as it is. is this what you all have been trying to get across to me?

it would still be safer with a back fed disconect right?
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Old 02-14-2011, 10:37 AM   #8
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Quote:
Originally Posted by treerat View Post
I think I finally woke up!

if I only have a 6 space lug panel, then I do not need a seperate disconect, because 6 space qualifies as a disconect as it is. is this what you all have been trying to get across to me?

it would still be safer with a back fed disconect right?
That is what they have been saying.
I would not back feed, because you never know when you might need another space.
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Old 02-14-2011, 10:49 AM   #9
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detached shed sub panel


Yes, if your subpanel has less than 6 handles, it counts as a disconnect. It is more convenient to have a local main breaker disconnect. If it were me, I'd replace that panel with a main breaker panel. As Allan said, as long as the breaker you are using in the main panel to feed your shed is sized properly for the wire, you can use any size breaker in the subpanel for your "convenience" shutoff.

Is it legal/safe to use a MLO panel, and instead of connecting the incoming feed to the Main Lugs, to connect them (backfeed) through a double-pole breaker? I believe that is what he is proposing.

Does he need 2 ground rods?
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Last edited by secutanudu; 02-14-2011 at 11:37 AM.
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Old 02-14-2011, 11:35 AM   #10
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detached shed sub panel


To use that welder at max capacity, you are going to need a 50 amp breaker. I would use #6 copper.

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