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Old 01-25-2008, 02:25 PM   #1
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Sub-Feed Lug Block


Sub-Feed Lug Block

Is this what I think it is? Is this positioned in the MAIN distribution panel to feed a sub-panel that has its own disconnect?

Is this preferable to having a breaker in the MAIN to feed the sub?
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Old 01-25-2008, 02:37 PM   #2
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Sub-Feed Lug Block


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Originally Posted by Randell Tarin View Post
Sub-Feed Lug Block

Is this what I think it is? Is this positioned in the MAIN distribution panel to feed a sub-panel that has its own disconnect?

Is this preferable to having a breaker in the MAIN to feed the sub?

Unforetally this item i am not too crazy with this device for few reason one .,,

this subfeed block do not have any OCPD [ over current protection device ] at all.,,

second thing that that subfeed lug block is good up to 125 amp but be very carefull here if you have any overload or short circuit it will trip the Main breaker in the box and leave the whole house in dark.

and also it dont have any disconnection in case you have to work on subfeed breaker box that mean you have go back to main breaker box and shut the main breaker to kill it.

third but very impoart part is the size of conductor[s] if you going to use that subfeed block you must match the conductor size to the main breaker.

anyway IMO i rather used the standard breaker to go to subfeed box to be more safer this way.

Merci, Marc

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Old 01-25-2008, 06:15 PM   #3
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Sub-Feed Lug Block


Randal

Are these sub-feed lugs what the feeder to the house is using?

If so they would need to be rated minimum 200 amp sub-feed lugs, most in this range are rated 225 amps and the other rating is 125 amps as frenchy said. Yours need to be to be minimum 200 amp tap lugs.

You are permitted with the inspectors approval to use these under the unlimited tap rule since your dwelling panel is 300 feet away. The rule is posted below if you don't understand ask questions.

Outside Secondary Taps of Unlimited Length [240. 21(C)(4)]
Outside secondary tap conductors can be of unlimited length without overcurrent protection at the point they receive their supply, but they must be installed in accordance with the following requirements:
(1) The conductors are suitably protected from physical damage.
(2) The conductors terminate at a single circuit breaker or a single set of fuses that limit the load to the ampacity of the conductors. This single overcurrent device shall be permitted to supply any number of additional overcurrent devices on its load side.
(3) The overcurrent device for the conductors is an integral part of a disconnecting means or shall be located immediately adjacent thereto.
(4) The disconnecting means for the conductors must be installed at a readily accessible location complying with one of the following:
a. Outside of a building or structure
b. Inside, nearest the point of entrance of the conductors
c. Where installed in accordance with 230.6, nearest the point of entrance of the conductors

Taken from an article written by Mike Holt enterprises

Last edited by Stubbie; 01-25-2008 at 09:10 PM.
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Old 01-25-2008, 06:26 PM   #4
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Sub-Feed Lug Block


No, Stubbie. I'm using breakers for the feed to my home.

I came across these while shopping for a subpanel. I had never heard of them and was just curious about them because I wondered if this was what I was supposed to be using in the MAIN.

Since I'm about to connect a new sub-panel to my guest cottages and upgrade the sub-panel to my workshop, I wondered if there was any advantage to using these over breakers.
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Old 01-25-2008, 07:58 PM   #5
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Sub-Feed Lug Block


Not really other than cost because they are much cheaper to use on feeders that require big wire....in other words if I was running 100 amp wire from one outdoor 200 amp panel to another 100 amp rated sub panel in a detached structure I could choose to use a 100 amp breaker in the main panel and a 100 amp main breaker disconnect in the sub-panel.

NOTE: The seperate structure main disconnect can be outside or inside but it must be integral to the panel or serparated from it as a single disconnect for all power to that detached structure.

Cost equals 2 100 amp breakers.

If on the other hand I am allowed to use the unlimited tap rule I am not required to have overcurrent protection on the supply side of the feeder tap. So a sub-feed lug device like you have shown satisfies that requirement. Since I am essentially tapping the busses of the panel with it. Remember though the panel that you are tapping must be outside and not inside a dwelling in order to not have overcurrent protection required at the source. Then the feeder to the detached dwelling or building must be connected to the main disconnect (breaker) of the sub-panel. This main breaker disconnect must be sized to the ampacity of the feeder conductors and no more. So if 100 amp feeder conductors my main breaker in the sub cannot be larger than 100 amps. It can be smaller if you want. As frenchy said though any fault on the feeder and the main disconnect in the panel being tapped will trip removing power from both structures. However in my opinion if the feeder is in conduit there is little need to worry about this.

Cost equals feeder tap lugs (cheaper by far) plus one 100 amp main disconnect at the detached structure or main breaker in the sub-panel.



Image from Mike Holt website

Last edited by Stubbie; 01-25-2008 at 11:21 PM.
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Old 01-25-2008, 10:21 PM   #6
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Sub-Feed Lug Block


I really don't see any benefit in using anything but a breaker in the feed and another in the sub.

Thanks again, Stubbie

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