new house main disco/subpanel question

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Under the 08 code in Iowa now, wiring a new home with the main 200A loadcenter located in the center of the basement around 50' away. We will need a 200A breaker/meter combo outside of the house to feed the loadcenter. This of course makes the main panel a subpanel right? Since we have to go thru ceiling joists, pipes, etc., can I feed the loadcenter with a 3-wire SE cable such as 4/0-4/0-2/0. I thought I read somewhere if your subpanel controls all the circuits in the house, you don't need an egc going to the subpanel. Am I correct here?
 

infinity

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Since your main is located at the meter and your panel is a subpanel you will need 4 conductor SER cable between the main and the panel, and your grounding and grounded conductors will need to be separated in the subpanel.

Welcome to the forum. :smile:
 

mcclary's electrical

Senior Member
Location
VA
You're right,,,,4 wire ser ,,unless he puts a conduit in the slab from the meter outside. Make sure you turn up right at the panel location with less that 6 feet of conduit and you can use 3 wires. It's wotrh the pvc for the cost savings in wire.
 

augie47

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I assume where McClary's is going is to eliminate the outside disconenct altogether, keep the service condcutors outside by being underground. Such an installation here, would be discouraged, but pass.
 

hillbilly

Senior Member
I assume where McClary's is going is to eliminate the outside disconenct altogether, keep the service condcutors outside by being underground. Such an installation here, would be discouraged, but pass.
That's the way I understand it too.

If the cable is buried under concrete, it's considered as being outside.
230.6(1)

As long as the conduit turned up and placed the Main "nearest the point of entry" of the Service conductors, the OP could mount the meter base outside and run 3 conductor to the Main and be code compliant.
230.70(1)


Just my opinion
steve

Edited for spelling
 
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I'm not following this either. What if the service goes from the meter directly into the house above the basement ceiling? And I think I remember seeing somewhere also that if the subpanel controls all the circuits in the house, only 3-wire ser is needed.
 

augie47

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I'm not following this either. What if the service goes from the meter directly into the house above the basement ceiling? And I think I remember seeing somewhere also that if the subpanel controls all the circuits in the house, only 3-wire ser is needed.
wherever you saw "it", it was incorrect. The key is "sub-panel". Although not defined, any panel fed by the service must comply with 250.24 (5) Load-Side Grounding Connections. A grounded conductor shall not be connected to normally non–current-carrying metal parts of equipment, to equipment grounding conductor(s), or be reconnected to ground on the load side of the service disconnecting means except as otherwise permitted in this article.
If it's not the service panel of a SDS panel, the grounding and grounded conductors are seperate.

The decisionon the need for an outside service disconnect may vary, but once it's there, the neutral and ground are seperate from that point.
 

hillbilly

Senior Member
I'm not following this either. What if the service goes from the meter directly into the house above the basement ceiling? And I think I remember seeing somewhere also that if the subpanel controls all the circuits in the house, only 3-wire ser is needed.

If the Main disconnect is not directly opposite the wall, and the Service conductors don't enter close to the disconnect "nearest the point of entry", it would be a violation.

The problem is that you would have un-protected service conductors running through the house.
The un-protected service conductors can only (per code) travel a very short (debatable:)) distance into the residence before they must hit the Main disconect.
It's all about safety.

If you can't keep the inside Main close to where the conductors enter the home, you would need to mount the Main disconnect outside.
At this point, the inside panel would become a feeder (sub) panel, and would require a 4 wire feeder so that you could isolate the Grounded (neutral) conductor from the (bonded) equipment grounding conductor.

If you don't do this and run 3 wire service conductors (240V 1 phase as example) a distance into the residence, the wires are not protected by a overcurrent device, and if a short circuit occured in this cable(s), it could easily cause a fire, or worse.
Plus, the ground wire of the 3 wire cable would be carrying return (neutral) current in tandem with the (3rd) conductor also performing as the equipment grounding conductor.
This is not allowed inside a residence.

Whether or not this feeder (sub) panel carries all of the current used in the house doesn't matter, and has no bearing on the question.

just my opinion
steve
 

infinity

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Location
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I assume where McClary's is going is to eliminate the outside disconenct altogether, keep the service condcutors outside by being underground. Such an installation here, would be discouraged, but pass.
Why would a code compliant installation be discouraged?

He said that he has to run 50' across the basement. His two options are run the 3 conductor in a raceway "outside" of the building or install a main at the meter and run 4 conductors 50' to the panel.
 
Thanks for your replies. Sorry, I was out for a while. Running the main service underground in pvc around the house will not work either, because the loadcenter is 20' away from the outside of every wall. My only option is run the 4-wire ser from the 200a outside disco, which will be fine. I'm trying to get my head around this 2008 code. I already forgot the rebar connection to the #4 bonding wire on this house project. Luckily the walls hadn't been poured yet. Spending more time in the book than running wire.
 
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