I have a 50amp sub-panel that has the ground and neurtral as one. Is this correct?

I could swear I have read the code before and it said the main box has the neutral and ground as one(bonded), but any sub-panel after the main panel the ground and nuetral should be separted(not bonded).:confused:

I have asked 10 people this question and have gotten many different answers. Can someone who know the code shine a light on this for me.

Thanks

Chuck

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Originally Posted by cc4digital

I have asked 10 people this question and have gotten many different answers.

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That is because 95% of regular folks are mixed up about this and so are 30% of electricians.


If the sub-panel is in the same structure as the main then you MUST have separate grounding and neutral conductors. End of story.

If it is in a detached structure it gets tricky.
The latest NEC (2008) requires the SAME thing. Previous editions, which many folks are still under in some form, allowed a "3-wire" feeder such as what you have. The insulated neutral serve as both the neutral and grounding conductors. This was only allowed under certain conditions, such as not having ANY metallic paths between structures, like phone/catv/water pipes/etc.

A detached structure supplied by a feeder always requires a grounding electrode (ground rod).

stanfortyman:

That is one of the better explanation I have gotten.:)

This is my concern--In my case the garage is attached. The sub-panel in the garage is a 50amp panel. But the run to the main panel is 125-140 feet. The wire that was used was 8-3G Non-Metallic Sheathed Cable.(Coming out of the sub-panel to the attic--It comes out of the top of the sub-panel at about 6 feet and goes up the wall for about 4-5 feet. Correct me if I am wrong, but I think it has to be protected in metal conduit as it goes up the wall?)

I know that #8 wire is fine for 50 amps, but if I remember after a certain length you get voltage drop. Do you happen to know the voltage drop for 140 foot lengh?


Also my second question--My main panel is 200amps :). In the code how many 50 amp sub-panel can be on a 200amp main panel?

Lastly--The 50 amp sub-panel spaces are full. Does the code allow for a sub-panel to feed another sub-panel? Thus, the setup would be something like this--Main 200amps connects to 50amp sub-panel which then connects to a 30amp sub-panel(I would think the additional sub-panel would need to be less than 50amps?)

PS.. I am located in California, not sure if the codes are different regarding sub-panels.

If you are going to feed a separate building, you must ground the "B" or Subpanel at the detached building.

BTW, you must also use a grounding rod arrangement and you cannot tie the ground at the "B" or Sub Panel together at the main panel. The reason that you can not ground the two grounding systems together is to prevent any type of ground current caused by different potentials.

Quote:

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Originally Posted by cc4digital

The wire that was used was 8-3G Non-Metallic Sheathed Cable.(Coming out of the sub-panel to the attic--It comes out of the top of the sub-panel at about 6 feet and goes up the wall for about 4-5 feet. Correct me if I am wrong, but I think it has to be protected in metal conduit as it goes up the wall?)

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Depends. Is this cable subject to damage for this 4-5 feet?

Quote:

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Originally Posted by cc4digital

I know that #8 wire is fine for 50 amps, but if I remember after a certain length you get voltage drop. Do you happen to know the voltage drop for 140 foot lengh?

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First off, #8NM cable is good for 40 amps, NOT 50.
Voltage drop is a direct result of load. With no load there is no VD. At 140' VD is not much of a concern for a sub-panel, since the load varies and is not constant at all.
Even at a full 40A load the VD is respectable at 140' on #8cu.

Quote:

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Originally Posted by cc4digital

Also my second question--My main panel is 200amps :). In the code how many 50 amp sub-panel can be on a 200amp main panel?

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Many as you want. Really.

Quote:

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Originally Posted by cc4digital

Lastly--The 50 amp sub-panel spaces are full. Does the code allow for a sub-panel to feed another sub-panel? Thus, the setup would be something like this--Main 200amps connects to 50amp sub-panel which then connects to a 30amp sub-panel(I would think the additional sub-panel would need to be less than 50amps?)

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Yes, this is allowed.

Quote:

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Originally Posted by stanfortyman

That is because 95% of regular folks are mixed up about this and so are 30% of electricians.


If the sub-panel is in the same structure as the main then you MUST have separate grounding and neutral conductors. End of story.

If it is in a detached structure it gets tricky.
The latest NEC (2008) requires the SAME thing. Previous editions, which many folks are still under in some form, allowed a "3-wire" feeder such as what you have. The insulated neutral serve as both the neutral and grounding conductors. This was only allowed under certain conditions, such as not having ANY metallic paths between structures, like phone/catv/water pipes/etc.

A detached structure supplied by a feeder always requires a grounding electrode (ground rod).

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Stan is correct! Yet, I'm not going to agree with the percentages:D

To add: Some jurisdictions require four conductors (regardless of NEC) to a detached structure--my jurisdiction being one. The 2008 has caught-up with our local code.

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Depends. Is this cable subject to damage for this 4-5 feet?

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I thought it depended on if it the wire were exposed or in the wall. :eek:
Here is a quick picture-- http://zzimage.com/temp/DSC02710.JPG

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First off, #8NM cable is good for 40 amps, NOT 50

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My bad. You are 100% right. I was thinking of THHN #8
__________________________________________________ ________________

I am now thinking my best bet is to run another line from the main panel to a new sub-panel:rolleyes:
If I should decide to do this here are a couple of questions--

Conditions and Uses--
1) This will be run from main box to sub-panel thru an attic for a distance of 130-140 feet.
2) I would think THHN in conduit would be wise??? Not sure about NM Cable
3) Tempature in the attic would get warm as the location is Southern California--Thus, summer time outside temperature can reach 100, attic would be much higher than this.
4) The panel will be used for a wood work shop(biggest motor is 3hp). Currently, the most I can see on at one time would be--

• 6- 8' fluorescent shop light at 1.25 amps each~Total 7.5 amps--120 Volts Continuos
• 1- Small Window AC or Wall Heater~Total 15 amps-120 Volts Continuous
  
• 1-Shop Dust Collector--Total 12 amps--220 Volts Not Continuous
• 1-Table Saw--Total 18 amps--220 Volts Not Continuous

Given the above information I would think I would want to run four #6 THHN wire--2 hots, 1 neutral, and 1 ground. For conduit I would use EMT 3/4".
I would think a 50amp sub-panel should handle this load fine.

Questions-->
Is my above thinking correct? 50 amps sub-panel with #6 THHN wire.
I am unsure on the conduit--I have always used EMT, but my runs are not 140 feet. The size, I would think required would be 1" either PVC or EMT? Any suggestion on which one to use?
Am I forgetting anything?

Thank you stanfortyman, Washington1, donf for your feedback. It nice to get some feedback before starting something. This way you don't find out later you left something out.:eek: I have been there before and it really sucks.

I'm not going to hi-jack the tread, but you have a number of code issues in that pic.

Washington1--Ya, I did not do this wiring.
The only thing I did was the EMT to the light switch(not finished yet, needs a cover and clamps). The rest was this way when I bought the house. I am in the process of fixing it now. That is the main above reason I don't want to use this panel for my wood work shop. I didn't do the orgianl run which makes me really nervous.

Ok, now that you bought up the issue of code violations, let me test my knowledge with the code--
1) EMT needs clamps and switch cover.
2) Wire coming out of wall light in the wall needs to be removed
3) The Aluminum Wire coming out of the top of the sub-panel needs to be protect. EMT Conduit
4) The Romex going to the switch box need to be replaced with EMT 1/2 Conduit and THHN #12 Wire(Black, White, Green)
Not sure about these ones as being code Violation--
5) The Romex plugged into the wall outlet that goes to the Garage Open Motor. Not sure if this is legal? Makes more sence to hard wire into a junction box and run #12 THHN Garage Opener Motor.
6) The Orange extention cord goes to an outside light. Not sure if this is legal? But again to run #12 THHN in EMT to junction box then Water Tight flex to light.
7) The 8-3G Non-Metallic Sheathed Cable I would think would need to be in Conduit upto the attic to protect it from damage. I always thought the code specified a distance above the floor, but according to stanfortyman it is actually a question of of weather is can be damaged or not.

Code:

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Depends. Is this cable subject to damage for this 4-5 feet?

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8) I think they recently added to the NEC code that Garage outlets need to be GFI Protect on 15 and 20 amp

So, how did I do? Did I miss anything?

Bump--I was hoping to get a few respones to the below questions--

I am now thinking my best bet is to run another line from the main panel to a new sub-panel:rolleyes:
If I should decide to do this here are a couple of questions--

Conditions and Uses--
1) This will be run from main box to sub-panel thru an attic for a distance of 130-140 feet.
2) I would think THHN in conduit would be wise??? Not sure about NM Cable
3) Tempature in the attic would get warm as the location is Southern California--Thus, summer time outside temperature can reach 100, attic would be much higher than this.
4) The panel will be used for a wood work shop(biggest motor is 3hp). Currently, the most I can see on at one time would be--

• 6- 8' fluorescent shop light at 1.25 amps each~Total 7.5 amps--120 Volts Continuos
• 1- Small Window AC or Wall Heater~Total 15 amps-120 Volts Continuous
  
• 1-Shop Dust Collector--Total 12 amps--220 Volts Not Continuous
• 1-Table Saw--Total 18 amps--220 Volts Not Continuous

Given the above information I would think I would want to run four #6 THHN wire--2 hots, 1 neutral, and 1 ground. For conduit I would use EMT 3/4".
I would think a 50amp sub-panel should handle this load fine.

Questions-->
Is my above thinking correct? 50 amps sub-panel with #6 THHN wire.
I am unsure on the conduit--I have always used EMT, but my runs are not 140 feet. The size, I would think required would be 1" either PVC or EMT? Any suggestion on which one to use?
Am I forgetting anything?

Bump--Does anyone want to give me some feedback on the above.
Not sure what happened. I was getting great feeback then all of a sudden it stopped.