200 main breaker X 2

[Scott Falvey]

Why/what would the purpose be of installing a 200 AMP breaker/disconnect in the garage on the main supply when there is also a 200 AMP breaker in the Main panel? Would this cause a problem?

Possible scenario, I believe the garage is an add-on to the house and the local AHJ required the disconnect be installed because the main service now runs through the building down to the basement where the "old" panel is. The house is about 8 years old, I don't know how old the garage is.

Thoughts?

[Mike Whitt]

Originally Posted by sfalvey

Would this cause a problem?

No It is premissible to feed a panel as large or even larger than the service as long as the feeders are large enough to carry the total load

[Speedy Petey]

I suspect since the panel was only 8 years old when the garage was added they simply added the main disconnect outside and made the panel into a sub-panel.
Nothing wring with a sub-panel with a main breaker.

[Ben J. Gromicko]

Possibly adding the garage forced the builder relocated the meter. And when the meter was relocated, a main disconnect switch had to be added near the meter. Isn't there some type of rule where you have to have a main disconnect within 8 feet of the electrical meter? So maybe the meter was moved too far away from the panel, and a disconnect had to be installed in between the relocated meter and panel.
Huh? My brain hurts.

[Speedy Petey]

Yup Ben, that was exactly my point, that I didn't make very well.

The rule is the disconnect must be "nearest the point of entrance of the service conductors". This can vary from zero feet to as much as fifteen feet.
Most places it is 5'-6'.

I would assume when the garage was added it put the main breaker way too far into the house.
I have had to do this many times.

[Marc D. Shunk]

Sticking a garage on the end necessitates the main disconnect outside just so all that cable between the outdoors and the panel indoors will be fused (ie, have overcurrent protection). There are rules of thumb used from jurisdiction to jurisdiction, but very few will permit as much as 8 feet of unfused service cable indoors. Some allow none, others allow 3 feet, and others permit up to 6 feet if you put it in rigid metal conduit. The NEC does not spell out any particular dimensional maximum, but only contains verbage that requires unfused service conductors to be very short. When this can't be accomplished, such as would be the case when a garage is slapped on the end, then you're in a position of putting a main disconnect outdoors next to the meter, or immediately indoors in the garge on the back side of the meter.

[Ben J. Gromicko]

I'm trying to understand the rule of running 4 wires to the panel in a detached garage. Is that because the panel in the garage is required to be a sub panel, and therefore you have two hots (black and red) one white for the neutral bus bar and another (green i suppose) going to the grounding bus bar? 4 wires for four buses? Is that the reason for the 4 wire rule to the detached garage?

[Marc D. Shunk]

Originally Posted by bgromicko

I'm trying to understand the rule of running 4 wires to the panel in a detached garage. Is that because the panel in the garage is required to be a sub panel, and therefore you have two hots (black and red) one white for the neutral bus bar and another (green i suppose) going to the grounding bus bar? 4 wires for four buses? Is that the reason for the 4 wire rule to the detached garage?

You're s'zackly right. Subpanel means 4 conductors (or 5 if you're dealing with 3-phase). There were some exceptions for certain detached buildings up until the 2008 NEC that would permit some detached structures to be fed with 3-wire and not wired like a subpanel. Those permissions disappear as the 2008 NEC becomes adopted.

[Paul W. Abernathy]

ben...the reason is primarily because the 4th conductor in question is the Equipment Grounding Conductor needed to aid in the clearing of the breaker feeding that 'Sub-Panel"

Remember now...in the case that is proposed....the grounding electrode system will need to be established the detached structure.....as again grounding electrode systems have no effect on clearing any overcurent protection device.

Now....prior to 2008 NEC.....Three conductors are allowed as long as the conditions are met....they are specific and listed in 250.32(B)(2) if you would like some late night reading material....lol...

Basically the concept of sharing the grounded (Neutral ) conductor is going by the wayside for new installations because of the potential of objectionable currents (250.6(A)) and so on.......

I believe the 2008 NEC makes so nice.....but thats my opinion.

[Ben J. Gromicko]

Originally Posted by pabernathy

.Basically the concept of sharing the grounded (Neutral ) conductor is going by the wayside for new installations because of the potential of objectionable currents (250.6(A)) and so on.......

That's an SE cable. 3-wires.

An SER is a 4-wire cable.

Yes?

[Marc D. Shunk]

Originally Posted by bgromicko

That's an SE cable. 3-wires.

An SER is a 4-wire cable.

Yes?

SE is the generic reference to any type of Service Entrance cable. Type SEU is the "flat" stuff that is made in 3-wire, and that stands for Service Entrance, Unarmored (there was armored SE once upon a time, and it's a bitch to strip out). The 4-wire and 5-wire stuff is SER, for Service Entrance, Round.

Your service entrance could just as easily be conductors in conduit, or in a commercial application for a subpanel, type MC cable. With certain caveats, the service entrance and the feeders to the subpanels can be pretty much any wiring method. In the East, we'd see mostly type SE cable, and in the West you'd see mostly conductors in conduit.

[Paul W. Abernathy]

Originally Posted by bgromicko

That's an SE cable. 3-wires.

An SER is a 4-wire cable.

Yes?

Thats Correct......SE Cable is generally the (2) ungrounded conductors with a third grounded conductor. The SER like marc said has (2) ungrounded conductors,(1) Grounded and (1) Grounding ( equipment grounding conductor that is )

for the most part.......