Sub Panel Wiring Question

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LB75

George
Corporate Member
Let me preface my question by saying that I do have a pretty solid understanding of household electrical wiring. A few years ago I did all of the wiring from meter socket to main panel to outlets for the 200 amp service in my workshop so I do have some experience under my belt in how to add circuits to a main service panel. When it comes to adding a 50 or 60 amp sub panel I start to have some questions.

Here's the scenario, I am ready to restart my kitchen remodel and am in need of 2 new additional 20 amp circuits beyond what I have room for in the main panel (I have open breaker slots but the neutral bar is maxed out). Back in January we had a new HVAC system installed and as a result of that we were "gifted" with a now unused 50A 240V circuit terminated in a fused disconnect directly under the kitchen in the crawlspace. At the time I thought that would be huge help and that I could just turn that into a sub panel to feed the new circuits, location is ideal because getting wiring to that location from the main panel is nightmare due to the configuration of the walls and floors between them in our split ranch. The problem with that plan I have now discovered is that it is not wired with a 4 wire cable so I don't have a dedicated ground running back to the main which I understand is required for sub panels. I also realized that having the breakers for these two circuits located in the crawlspace is far from ideal so I decided it would be best to eliminate that circuit completely, pull a new 6/3 cable into the main panel and locate the sub panel in a more convenient location. So that's a very long story to get to my main question...

I know that the the neutral and ground bars need to be separate in the sub panel, with the ground bar bonded to the box, and that you need to have separate neutral and ground wires running back to the main panel along with the 2 hots. That's where the confusion hits me, my main service panel does not have separate neutral and ground bars. So does that mean I can't add a sub panel since I can't separate the neutral and ground in the main panel? If that's the case, I'm thinking the best course of action would be to add a separate ground buss, bond it to the panel and move all of the existing equipment grounds to it from the neutral buss to free up the space I need?
 
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Oka

Oka
Corporate Member
Main panel neutral (white) and ground are on the same buss. The sub-panel usually they are separated on their own buss.

In general your meter panel will have the 200Amp breaker. The Main service panel would have a a 200 amp disconnect (usually) then all other breakers would feed line voltage from there.

If you are tight for space you could add another subpanel and feed cirecuts from there and replace a couple of spaces in the main service breaker panel to install the breaker that would feed the subpanel. Make sure you do not over rate your main panel. That calculation look up not particually hard to calc but explaining it would be wordy. A youtube or instructional; site will have this explained way better than I will.
 

LB75

George
Corporate Member
Main panel neutral (white) and ground are on the same buss. The sub-panel usually they are separated on their own buss.

In general your meter panel will have the 200Amp breaker. The Main service panel would have a a 200 amp disconnect (usually) then all other breakers would feed line voltage from there.

If you are tight for space you could add another subpanel and feed cirecuts from there and replace a couple of spaces in the main service breaker panel to install the breaker that would feed the subpanel. Make sure you do not over rate your main panel. That calculation look up not particually hard to calc but explaining it would be wordy. A youtube or instructional; site will have this explained way better than I will.
Yeah, YouTube has been very helpful tonight. I have it all straight in my head now what I need to do, it's just a question now of if the existing main service panel I have will support it. I'm not in danger of overloading the panel, I'm just out of neutral bar space since I don't have a separate ground bar. Looks like I should be able to install one to move some of the ECGs over and solve my problem.
 

tvrgeek

tvrgeek
User
I think you need to talk to the inspector or an electrician. What works and what passes code may not be the same. Even though most codes are based off the NEC, they do vary a bit.

You can get larger neutral and ground buss bars.

Running an outlet is fine, but consider for eventual re-sale, if a sub-panel is not recorded as inspected, the home inspector should flag it and it could cost you a lot for an electrician then.
 

Charles Lent

Charley
Corporate Member
Add a ground buss to your main panel and move the ground wires that are on the neutral buss over to it. You should then have plenty of neutral positions to use. In your shop panel you should have separate neutral and ground busses, and the ground buss needs a driven ground rod connected to it, as well as connection back to the ground buss in the main panel.

Charley
 

Jeff

Jeff
Corporate Member
Despite your electrical experience you are not a licensed electrician. Your safer and more expedient way is to simply hire a licensed electrician to make the needed modifications that also will meet codes.
 

Pop Golden

Pop
Corporate Member
I hired an electrician to put in my new main panel & wire the old existing panel as a sub-panel. I took it from there and wired my shop. My lighting is split between the shop sides. That way if you need to work on lights one side of the shop will remain lit. My lights are on 2 15 amp circuits. I have 1 15 amp circuit for my sanders & HVLP system. 2 220 vac 20 amp for my plane & table saw. Everything else is 20 amp. I am a one man shop, but I still put most machines on separate breakers.

Pop
 

CrealBilly

Jeff
Senior User
Let me preface my question by saying that I do have a pretty solid understanding of household electrical wiring. A few years ago I did all of the wiring from meter socket to main panel to outlets for the 200 amp service in my workshop so I do have some experience under my belt in how to add circuits to a main service panel. When it comes to adding a 50 or 60 amp sub panel I start to have some questions.

Here's the scenario, I am ready to restart my kitchen remodel and am in need of 2 new additional 20 amp circuits beyond what I have room for in the main panel (I have open breaker slots but the neutral bar is maxed out). Back in January we had a new HVAC system installed and as a result of that we were "gifted" with a now unused 50A 240V circuit terminated in a fused disconnect directly under the kitchen in the crawlspace. At the time I thought that would be huge help and that I could just turn that into a sub panel to feed the new circuits, location is ideal because getting wiring to that location from the main panel is nightmare due to the configuration of the walls and floors between them in our split ranch. The problem with that plan I have now discovered is that it is not wired with a 4 wire cable so I don't have a dedicated ground running back to the main which I understand is required for sub panels. I also realized that having the breakers for these two circuits located in the crawlspace is far from ideal so I decided it would be best to eliminate that circuit completely, pull a new 6/3 cable into the main panel and locate the sub panel in a more convenient location. So that's a very long story to get to my main question...

I know that the the neutral and ground bars need to be separate in the sub panel, with the ground bar bonded to the box, and that you need to have separate neutral and ground wires running back to the main panel along with the 2 hots. That's where the confusion hits me, my main service panel does not have separate neutral and ground bars. So does that mean I can't add a sub panel since I can't separate the neutral and ground in the main panel? If that's the case, I'm thinking the best course of action would be to add a separate ground buss, bond it to the panel and move all of the existing equipment grounds to it from the neutral buss to free up the space I need?
Call the manufacturer of the panel box ask them if the box is still under warranty if you remove the ground/neutral strap. I bet the answer is no.
 

junquecol

Bruce
User
Call the manufacturer of the panel box ask them if the box is still under warranty if you remove the ground/neutral strap. I bet the answer is no.
Depends. Does manufacturer make a ground bar kit for panel box? If so, then the answer is a yes, well, maybe. Your 50 amp circuit under house was for HP blower coil, with 10KW heat strips, all of which ran on 220. If it had been four wires (2 hots, neutral and ground,) you could have used it as a junction box. The hots and neutral could be "wire nutted for their connections, but the ground would need to be in a bus bar, bonded to the box.
 
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LB75

George
Corporate Member
Depends. Does manufacturer make a ground bar kit for panel box? If so, then the answer is a yes, well, maybe. Your 50 amp circuit under house was for HP blower coil, with 10KW heat strips, all of which ran on 220. If it had been four wires (2 hots, neutral and ground,) you could have used it as a junction box. The hots and neutral could be "wire nutted for their connections, but the ground would need to be in a bus bar, bonded to the box.
Yep, I've abandoned the sub panel idea. I was able to get the ground bars for the GE panel today and am going to add them so I can move some of the grounds off the neutral bus. Also going to just eliminate that old 50A circuit while I'm at it.
 

CrealBilly

Jeff
Senior User
Yep, I've abandoned the sub panel idea. I was able to get the ground bars for the GE panel today and am going to add them so I can move some of the grounds off the neutral bus. Also going to just eliminate that old 50A circuit while I'm at it.
Metering off the pole underground here at the farm. So every box is a sub panel, I have 5 sub panels, all 5 are strapped and grounded to a copper rod and clamped with 4ga copper wire.

Electricity is lazy, it take the path of least resistance, neutral current wants to find ground and with it only a few feet away from the panel box that's the path it will take.

Just don't be a dumbo and connect ground to the lightening rod's ground. That's how the barn was grounded when I bought the place. It took me a little bit to figure out why every time I pulled a plug it arced. Being a steel barn and steel conduit, the whole barn was acting as ground. Which it should be, but not the power company's ground.

I literally have several hundred feet of burired copper wire to power all the buildings. Even being the last pole on the road, I have the cleanest power I've ever had anywhere I've lived, not even a light flickers. I want to believe it's because of grounding.

BTW, funny story... the electrician I hired to trench a new main, told me of a man who does all his welding on Sunday. Why Sunday? Because Ameren doesnt work on Sunday.
 
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tvrgeek

tvrgeek
User
Farm wiring has different requirements as cows are super sensitive to trickle currents in the ground. Around here, you can't use armored cable in a barn due to corrosion, thin wall or plastic is required. Some allow smurf tube, some do not.

Codes differ where neutral and ground are tied and where rod(s) are needed. Distance matters. One has to look at possible failure modes to determine if improper paths can occur. Even the licensed master who put the panel in my workshop made a mistake not puling the strap on the panel. Good inspector.

Codes cover a lot of things you may not think about. Following " works for me" is very poor advice.

BTW, big steel buildings are famous as electro-static collectors. Grounding correctly is critical.
 
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