ELECTRICAL QUESTION

[lenray]

I have a property that has a 200 amp breaker box and a wire runs from it to a small outbuilding. In the outbuilding is a SQ D Q O Load center..Series G o4..
A 30 AMP breaker is in the 200 amp box. In the out building there are three 20 amp breakers..The breakers run the lights and two plugins..HERE IS THE QUESTION----From the 200 amp breaker comes three wires white-black and uncovered ground. All copper...there isn't a main shut off in the load center--just the three 20 amp breakers. The three wires seem to be hooked up to the neutral and grounding bars....

 

[kcm.MN]

1. What gauge wire is running from the main box to the secondary box? Need to know that in order to know how much load the wire can handle.

2. You mention 3 circuits in the shed connected to outlets and lighting. What combination? Is one breaker all lighting and the other two outlets, or????

3. And NO!, you cannot max out all three 20A breakers without first tripping the 30A in the main box -- or at least that's how it's SUPPOSED to work. :wink:

4. What kinds of tools/equipment are used in the shed, and what is the max load at any given time during the year?

 

[Jim.ME]

I may be misunderstanding what you are saying but it is very highly unlikely the three wires are only hooked to the neutral and grounding bars in the outbuilding load center. I have to believe the breaker in the main panel would trip as soon as you flip it on, if that was the case.

Post a picture of the load center in question showing the connections you are asking about. Is the 30amp breaker in the main panel a two pole (for two wire 220/240 volt) or single pole breaker (for 120 volt)? Guessing the three 20-amp breakers in the load center (sub panel) are single pole breakers.

 

[lenray]

The single breaker in the main box is a single pole 30 AMP...I only know how to send a picture is to someones phone number....Only half of the positions in the shed are HOT. Maybe it should have been a double pole in the main box. Only need the three breakers in the load center. The three breakers in the load center are single pole..Thanks for your help...

 

[lenray]

The wire is to short on both ends to see the information concerning wire size. My guess is that it is 8 copper. One breaker is for lights--the other two breakers go to just one outlet a piece..Small usage---battery charger-skill saw-drill. The 30 AMP in the main box is a single pole and only every other position on the load center is hot.

 

[rvirgil_KS]

Only half of the positions in the shed are HOT. The load center is designed for 240 volts which splits into 2 120 volt legs of opposite phase. Your incoming 120 volt line only feeds one phase of the load center.

With this setup your breakers must be in every other slot.

At the out building your bare wire should go to the ground buss bar, the white wire to the neutral buss bar, and the hot black wire to the main input.

The ground buss and neutral buss should not be bonded together.

 

[Jim.ME]

If only half the positions in the sub panel are hot it sounds like the black wire may be hooked to one power buss, the white is to the ground bar, and the bare to neutral.

It would have been best to use a two pole 30-amp breaker in the main panel so as to take 220/240 to the sub panel. I believe for 30 amps the wire should be at least 10 gauge (possibly heavier depending on distance. It should have 4 conductors (black, red, white, and bare). In the subpanel the Black and red would go to the two power connections, either the terminals of a two-pole main breaker or the two buss bars for the breaker connections. White to the neutral bar and bare to the ground bar.

You will be limited to a total of 30 amps draw on the main. You cannot pull 20 on all 3 breakers in the sub panel at the same time. If you aren't sure of what you are hooking up it would be best to contact an electrician, there may be some code requirements to be considered here.

 

[lenray]

Jim there are ONLY three-3--WIRES going from the main box to the load center..I bought the property and this is how it was wired. I understand to be correct and a double pole 30 in the main there should be 4 wires..

 

[lenray]

Thank you rvirgil....being that there are only --3--wires--going from the main box--Black-White -and bare..And I don't need much in the outbuilding as far as power. Is it OK to just have every other one being hot???

 

[old]

It's okay to do that but not up to code as such. My shop has a 3 phase breaker box but only single phase power so only 2 breaker slots out of 3 work. I got the breaker box cheap at an auction

 

[Jim.ME]

Lenray, I understood there were three wires currently. I said it would have been best to use a two-pole breaker and if that was done the wire should have 4 conductors.

As I last posted. "If only half the positions in the sub panel are hot it sounds like the black wire may be hooked to one power buss, the white is to the ground bar, and the bare to neutral."

Yes, it will work for your needs with only every other position having power.

 

[tech4]

I am not an electrician or trying to get in to an argument about the legality or code requirements of this set-up but I think the QO breakers are dual circuits with 2 circuits on each breaker. It sounds like it is being fed with a single 120 volt input with only 3 conductors. This would have only one circuit active from each dual breaker. One circuit would be inactive on each breaker. I see how it could work and as I said I am not commenting on the size of wire, grounds, neutral and general code requirements.

 

[Jim.ME]

I might be reading things wrong but from info I find QO breakers are available in styles from 1 pole to 4 poles. Given lenray has said the main is a single pole 30-amp breaker, I am assuming (and may be wrong) that the sub panel has 3 single pole breakers in it setting in every other slot.

 

[lenray]

That is correct Jim...Thanks for the help...

 

[Stephen Newell]

As long as the wires going out from the 20 amp breaker are not smaller than 12 gauge I don't see a problem. Combined if you draw more than 30 amps it would trip the breaker in the 200 amp box. Is the wire from the 30 amp breaker 10 gauge or more? The breakers should be rated with the wires attached to them. 20 amp is for 12 gauge wire and 10 gauge is for 30 amp.

 

[kencombs]

If you changed the 30A breaker to a 2 pole version you would need another hot conductor panel to panel.

As I see it, your current setup is fine for 120v IF the wire panel to panel is 10ga or bigger and you don't need 240v out there. you have a separate neutral and safety ground, same as with a 4 wire, 240v service.

But, if it were mine I would add a ground rod at the outbuilding.

 

[John T]

Len, I apologize I'm having trouble following your question so I will try to figure this out and help you.

1) Based on (what I UNDERSTAND from your statement ?? I may be confused) your statements:

A) The breaker in the main box that feeds your outbuilding is a SINGLE Pole 30 AMP RIGHT ????

B) From the 200 amp breaker (You mean from the 30 amp breaker in the main panel??) comes three wires
white-black and uncovered ground that go to the outbuilding RIGHT ???? .

IN THE EVENT there is a SINGLE POLE 30 Amp breaker in the main panel that feeds power to the
outbuilding ................. THAT CORRECT ????

THAT INDICATES (A) You are ONLY running a single leg of 120 VAC to the outbuilding and the three wires
(B) Are Black Hot,,,,,,White Neutral,,,,,,,Uncovered Equipment Grounding Conductor.

a) That is fine iffffffffffff you ONLY need a single leg of 120 VAC to the outbuilding.
b) That is fine PROVIDED at the outbuilding the Neutral Buss and Equipment Ground Buss ARE SEPERATE
INSULATED AND ISOLATED FROM EACH OTHER
c) Since the out building service requires Grounding, I would drive a ground rod there.
d) Subject to the outbuildings panel, ONLY every other buss (to which breakers attach) is hot
e) As indicated for ONE leg of 120 VAC FROM main TO sub, THREE WIRES SUFFICE Hot, Neutral, Ground

HOWEVER if you wanted 120/240 Volt at the outbuilding with both breaker buss hot, YOU WOULD NEED A TWO POLE BREAKER AND RUN FOUR WIRES OUT...... L1 L2 Neutral Ground

I purposely am NOT getting into wire and breaker sizes as it wasn't your question and would get even more confusing lol

Soooooooo is this how its wired ?? If so see my comments. Let me know and post back any questions. As always any Electrical or Legal questions draw out more responses and opinions than most others, so if in doubt where fire and life safety are concerned you might consider consulting the NEC and professional electricians and engineers DO NOT TAKE MY WORD FOR IT Im a long retired electrical power distribution design engineer and rusty as an old nail grrrrrrrrr on the latest codes

John T Yall have a good day now best wishes

 

[dr sportster]

You mean separate neutral and ground bars?

 

[John T]

EXACTLY (at sub panels) separate insulated and isolated from each other while the panels metallic case/frame still bonds to the Equipment Ground, but we already know that yayyyyyyyyy

John T

 

[lenray]

Hello John you followed exactly as I was trying to share the info. Here is how the 3 wires are hooked up to the load center. The bare copper is to the ground bar.....The white wire is hooked to where the breakers are located...The Black wire is on a lug alone and kind of behind the ground bar. It seems to work, but I WAS CONCERNED IF IT WAS CORRECT.
My wife and I HAD A 41 FT. diesel pusher-Newmar. We loved to travel as you and your Lady do. I am on year 4 without HER. HARDEST 4 YEARS OF MY LIFE..As you know each day together is a Blessing....Thanks for your help. Does the 3 wire set up seem to be wired correctly???? Also I have installed a ground rod at the panel.

 

[John T]

Hi Len, sorry for your loss and thanks for the feedback.

When you state: The white wire is hooked to where the breakers are located...The Black wire is on a lug alone and kind of behind the ground bar.

YIKES Im not sure of what you mean ?? but based on how its actually wired ??? it sounds like it COULD BE WRONG AND DANGEROUS assuming your wire colors match the standard ?? The correct wiring colors are Black HOT, White Neutral, Bare/Green Equipment Ground.

The Incoming from Main panel wires are attached: Black to the circuit breaker connection terminal/buss (The bars to which the breakers attach when inserted) or the main breaker input terminals if it were so equipped,,,White to Neutral Buss,,,Bare/Green Ground to Ground Buss

NOTE on some panels used as the Main, the Ground Buss Bar and Neutral Buss Bar are one and the same where BOTH all Whites and all Grounds attach,,,,,,,On some the two Buss Bars are separate one on each side and iffffffff its the Main panel a cross tie bar joins and electrically connects the two together. A Green grounding bonding screw can be used for Bonding (if the Main panel) and grounding the panel

HOWEVER on a sub panel fed by the Main panel (your case to outbuildings sub) the Ground and Neutral bars must be separate insulated and isolated from each other, White Neutrals to Neutral Buss,,,,,,, Bare/Green Ground wires to Ground Buss. With only THREE wires to the sub you ONLY have one leg of 120 which is fine if thats all you need (sounds okay for a few lights and receptacles) its just that all/half the circuit breaker slots may not be hot. The SINGLE Pole breaker in the main is whats needed and fine since youre ONLY running one leg of 120 out using 1 Hot, 1 Neutral, 1 Ground


Got it now?? Clear as mud ?? hey now you got me confused lol need a good picture

John T

 

[lenray]

Hello John I am 77 and only know how to send a picture using my phone and sending it to another phone number...My email is open- I understand if you are not comfortable sending me a number. I guess I can only send to a cell phone.

 

[lenray]

Maybe the white and black are reversed....Maybe someone could walk me thru how to put a picture on here with me using me cell phone.....

 

[JMOR]

Maybe you can talk to this John & lenray.

with added ground rod connection:

added grounding info:

This post was edited by JMOR on 08/11/2022 at 11:59 am.

 

[John T]

Hey JMOR, nice pics, that may help Len,,,,,,Hey Len, the Black Hot from the Main panel goes on top to
EITHER a Main circuit breaker ifffffffff it has one, otherwise to the big main top left stud/nut that
connects/feeds the left side bar the circuit breakers plug into. Incoming White Neutral to the Neutral
Buss on the right. Incoming Ground to the Ground buss on left. In your case of a sub panel there IS NO
CROSS TIE FROM BUSS TO BUSS. Any green bonding screw bonds the panels case/frame to the Ground Buss.

Top left corner are the three incoming wires from the Main panel

Maybe that helps ???? If so you have JMOR to thank

Yo JMOR you have any tips for Len ??

John T

 

[JMOR]

(quoted from post at 16:09:31 08/11/22) Hey JMOR, nice pics, that may help Len,,,,,,Hey Len, the Black Hot from the Main panel goes on top to
EITHER a Main circuit breaker ifffffffff it has one, otherwise to the big main top left stud/nut that
connects/feeds the left side bar the circuit breakers plug into. Incoming White Neutral to the Neutral
Buss on the right. Incoming Ground to the Ground buss on left. In your case of a sub panel there IS NO
CROSS TIE FROM BUSS TO BUSS. Any green bonding screw bonds the panels case/frame to the Ground Buss.

Top left corner are the three incoming wires from the Main panel

Maybe that helps ???? If so you have JMOR to thank

Yo JMOR you have any tips for Len ??

John T

ooks like you covered it.

 

[lenray]

OK FELLAS I have pic of the load center up above under test trying to post a pic---the white wire in question is on the right in a big lug next to a 20 amp breaker. Someone had the white and black on a 60 amp breaker in my 200 amp outside box---wire way to small. I removed the 60 amp and replaced with a single pole 30 amp. of course now only have of thee breakers now work. only have 2 lights and one plug in in the building..Thinking the WHITE WIRE IS NOT CORRECT...Thanks for all the help and also you guys who helped me put on a pic...

 

[Mike Groom]

It sounds like the same box I installed yesterday, it was a Square D Homeline model. The white neutral should go to the right side top lug that is connected to the bare strip with multiple screws in it for additional white (neutral wires). On the left top lug you will connect the black hot wire. The ground (bare) wire should be on its own grounding strip- (not supplied) this strip feeds back to the main box in the house and you connect the bare wires from the outlets, lights,etc. to that. If you need to use all 6 lugs for breakers you need to run a # 10 jumper wire from te left side under the breakers over to the lug on the right side to connect the strip with the other 3 lugs to the supply.Of course the black wires from the outlets, lights,erc. go to the individual breakers.