Need some wiring clarification-detached garage subpanel

[pault28]

Hello all,
I went to help a friend install a 50amp 230v breaker and outlet for a welder he bought. The 100amp subpanel is in a detached garage and is connected to the house by buried conduit. Installing the welder outlet, I ran 8awg wire through 3/4" conduit back to the panel...very short run, only a few feet. So we kill the power to the subpanel from the main breaker and I install the 50amp breaker and tie the two hot lines to it. I then look to hook up the ground wire to th ground terminal bus. This is where I am confused. In his subpanel, the neutral from the main panel is connected to a neutral bus. However, the electrician who originally connected it did not tie any of the 110v circuits to this bus. The neutrals are connected to a bus on the other side of the subpanel along with the ground wire from the main panel. Seems to me the ground and neutral busses are tied together. Isn't that a no-no? I thought I'd have to tie the ground wire from the welder outlet to the ground bus but it seems to be tied to neutral too. Is this dangerous? Metering the hot subpanel lines and each of the ground/neutral buses yields 115v. I tied the ground from the welder circuit to the bus. Now metering the welder receptacle yields 115 from each side and 230 across both hots.

Pic of subpanel showing my breaker wiring as well as where I installed the ground on the left from the welder receptacle...


Pic of main panel showing where the main neutral coming in from the utility as well as the neutral going to the garage subpanel ties in on the right side. Utility neutral is on top of right bus and the subpanel neutral curves around and ties into the bottom of the right neutral bus...


I apologize for the long post, I'm trying to be thorough with my explanation as well as questions.

By he way, it seems that everything is working fine. We ran the welder and it worked just fine. I did however have him kill that breaker after we tested it just until we are sure what we did was safe and correct. Maybe I could have left the ground wire from the receptacle out since it is connected via conduit all the way to the main box?

 

[pattenp]

Yes the sub-panel is set up wrong. The neutrals should be isolated from the ground. The sub-panel needs a ground bar added. Also the wire that I assume is the ground from the main panel should be green not black if smaller than a #4. If the black ground wire is #4 or larger it can be taped green.

 

[justsam]

In addition to above you will also need a local ground, rods driven in the ground or Ufer ground tied to rebar in slab. The ground bar in the subpanel will be connected to this.

When was the subpanel installed? Are you sure that is a 4 wire feed all the way from the main panel, or is it a local ground? In the past 3 wire feeds were acceptable.

 

[pattenp]

It appears the conduit is used for the equipment ground. But I see no separate electrode ground conductor.

 

[pault28]

In addition to above you will also need a local ground, rods driven in the ground or Ufer ground tied to rebar in slab. The ground bar in the subpanel will be connected to this.

When was the subpanel installed? Are you sure that is a 4 wire feed all the way from the main panel, or is it a local ground? In the past 3 wire feeds were acceptable.

There are the 3 large gauge wires, 2 hots and the neutral as well as a slightly smaller wire that goes back to the main panel and ties direct to the panel which I believe is a separate ground. You can see the smaller wire coming out the feeder hole in the subpanel and it ties to the subpanel chassis then goes up to the right neutral terminal bus. Maybe this was done instead of a local ground? Subpanel was installed a few years ago when the new garage was built.

 

[pault28]

Yes the sub-panel is set up wrong. The neutrals should be isolated from the ground. The sub-panel needs a ground bar added. Also the wire that I assume is the ground from the main panel should be green not black if smaller than a #4. If the black ground wire is #4 or larger it can be taped green.

There is a smaller gauge wire right from the main panel in addition to the 3 larger ones that is taped with green tape, I believe it is 4awg. I didn't put it in though so I cannot say that with absolute certainty.

 

[pault28]

Since it looks like the smaller 4th wire is grounded to the actual subpanel, and goes back to he main panel where it is also grounded to that panel, can I just install the little rigid jumper to the left bus. If I am understanding its purpose correctly, that is used if you want to ground that particular bus to the chassis? If I did that and moved the heave gauge neutral from the left side to the right side and the ground wire that also attaches to the panel chassis from the right side to the left where the rest of the neutrals are would that suffice? I think that would make the right side my neutral bus and the left side the ground bus.

 

[Evan(CA)]

I can't tell from the picture but it looks like the circuits are running through conduit and using the conduit as the ground. The bus bar on the left is meant to be the ground bus. You can see the little ground arm in the picture. Loosen the screw and bond it to the bus on the left. In your situation as a friend helping a friend just move the neutral feeder from the left to the right bus bar, make sure any grounds are on the left and neutrals are on the right and call it good.

 

[pattenp]

I can't tell from the picture but it looks like the circuits are running through conduit and using the conduit as the ground. The bus bar on the left is meant to be the ground bus. You can see the little ground arm in the picture. Loosen the screw and bond it to the bus on the left. In your situation as a friend helping a friend just move the neutral feeder from the left to the right bus bar, make sure any grounds are on the left and neutrals are on the right and call it good.

Nope, don't do that. The 2 bars are tied together with a long strap behind the buss. You need to leave those bars unbonded to the case and install a ground bar that is bonded to the case. All grounds will land on the ground bar and all neutrals will land on the 2 neutral bars to be isolated from the grounds. The panels come set up to be used as a main panel where the grounds and neutrals are bonded. When used as a sub-panel the small bonding strap is removed and a ground bar kit is to be added.

 

[wyliesdiesels]

Wow nice hack work. Shouldve used green EGC and a separate ground bar! Also do u have ground rods?

 

[pault28]

Wow nice hack work. Shouldve used green EGC and a separate ground bar! Also do u have ground rods?

The subpanel installation was not my work. There is no ground rod for the garage subpanel, but the main panel in the house has one. There are just the two hots, one neutral, and a smaller ground which is grounded to the subpanel box as well as the main box in the house, all run in EMT. All I want to do for him is make it safe, I'm just doing a favor with the new receptacle. It seemed fishy which is why I posted here.

 

[wyliesdiesels]

Well as has been said, add a ground bar kit and move the smaller ground wire to the ground bar. Technically, u dont even need the EGC wire as the conduit is metal. Make sure to move any branch circuit EGC/ground wires from the neutral bars over to the new ground bar.

Also put in 2 ground rods and use bare #6 cu to tie them together.

 

[Evan(CA)]

Nope, don't do that. The 2 bars are tied together with a long strap behind the buss. You need to leave those bars unbonded to the case and install a ground bar that is bonded to the case. All grounds will land on the ground bar and all neutrals will land on the 2 neutral bars to be isolated from the grounds. The panels come set up to be used as a main panel where the grounds and neutrals are bonded. When used as a sub-panel the small bonding strap is removed and a ground bar kit is to be added.

Oops thanks for catching that. However it's just screwed into a lug and can be cut or bent back after you loosen the lug screw to isolate the bus bars. Looks like it might be easier to do that on the right side though.

 

[Jaramie_Wilson]

It is safe. Just not code. The power from the poco only has 2 hots and a neutral. He did the same thing. In the meter can its all tied back together when it hits the poco system all the way back to the substation then it hits the station ground system underground. All tied together. Dont worry about it.

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[dw1]

You could see if you can remove the bonding strap (Black insulated strap connecting both bars) if so, put all neutrals on the right isolated bar, connect the bonding strap that is not connected on the left bar (this bonds the left ground bar to the panel frame) connect all grounds here. PS looks like a 12 circuit main lug panel, detached structure should have a main breaker, I bet you add more breakers before its over. You wont have to buy a ground bar kit this way.

 

[wyliesdiesels]

it is safe. Just not code. The power from the poco only has 2 hots and a neutral. He did the same thing. In the meter can its all tied back together when it hits the poco system all the way back to the substation then it hits the station ground system underground. All tied together. Dont worry about it.

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wrong! Wrong! The OPs feed is 4-wire. PoCo is only 3-wire.

Also, neutral current could flow on grounded pathways. This is just the reason to have an isolated neutral in subpanels!

View media item 16967

 

[Jaramie_Wilson]

Neutral current flow does in fact flow on a grounded path way, it will find the fastest and easiest way to a ground. Weather its the owners ground rods, utilitys power pole ground rods or the substation ground grid. All its doing it finding the quickest path back to earth.


What do you think a neutral is? Or were it ends up at?

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[Redwolf947]

Pault28,
I would remove that strap between those 2 bars if I could. I'd move the neutral on the Right isolated from the can tie the left bar to the can with the little strap there and run your ground to that. Then separate the neutrals and ground respectively. I would think about also adding ground rods and run them to the ground bar as well. If you can't remove the strap I'd get the ground bar kit for that brand can and run all grounds to that. Hope this helps.

The diagram wyliesdiesels posted is what you should follow...

View media item 16967[/QUOTE]

 

[pattenp]

Don't waste your time removing the bar connection strap. Just buy the $5 ground bar kit as intended by the manufacturer. It's a lot easier.

 

[Norcal]

Neutral current flow does in fact flow on a grounded path way, it will find the fastest and easiest way to a ground. Weather its the owners ground rods, utilitys power pole ground rods or the substation ground grid. All its doing it finding the quickest path back to earth.
What do you think a neutral is? Or were it ends up at?

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A fault is NOT trying to return to earth, it is trying to return to it's source which in this case is the PoCo transformer, the fault will take all paths which the earth is one path.

 

[justsam]

Neutral current flow does in fact flow on a grounded path way, it will find the fastest and easiest way to a ground. Weather its the owners ground rods, utilitys power pole ground rods or the substation ground grid. All its doing it finding the quickest path back to earth.


What do you think a neutral is? Or were it ends up at?

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I think this notion would tend to negate proper operation of GFCI's today. It is looking for equal amounts of current on the hot, returned to the neutral. If some of that "neutral" current is going via the EGC than that would be seen as a fault by the GFCI, assuming a greater than 5mA difference.

 

[Charles (in GA)]

Nope, don't do that. The 2 bars are tied together with a long strap behind the buss. You need to leave those bars unbonded to the case and install a ground bar that is bonded to the case. All grounds will land on the ground bar and all neutrals will land on the 2 neutral bars to be isolated from the grounds. The panels come set up to be used as a main panel where the grounds and neutrals are bonded. When used as a sub-panel the small bonding strap is removed and a ground bar kit is to be added.

The LH bar is intended to be used as a ground if needed, Simply remove the bonding strap that ties the two together, and take the Z shaped bonding bracket that is next to the white wire with the green tape, and stick it in the bar and tighten up the screws. That makes the LH bar a ground and the RH bar a neutral. Put the neutral wire on the RH bar, and run a solid #6 from the panel to the two ground rods. Put all the grounds on the left, and the neutrals on the right.

Its a small panel, no need to waste time and money going out and buying a ground bar, when you got one in the panel. If it were a large panel, I'd say great, you got a neutral on each side, but its such a small panel, it just don't need a third bar cluttering it up.

Charles

 

[pattenp]

The LH bar is intended to be used as a ground if needed, Simply remove the bonding strap that ties the two together,

Charles

I politely disagree with you on this. The strap that goes behind the breaker buss connecting the two bars is not intended to be removed and is not recommended to be removed by the manufacturer. This is why the manufacturer provides a ground bar kit.

 

[Norcal]

I politely disagree with you on this. The strap that goes behind the breaker buss connecting the two bars is not intended to be removed and is not recommended to be removed by the manufacturer. This is why the manufacturer provides a ground bar kit.

Another reason not to do it is the box does not always get bonded to the ground bar because they are insulated, while with a proper ground bar kit they are done automatically. It is a piss poor practice to remove a split neutral.

 

[Jaramie_Wilson]

I think this notion would tend to negate proper operation of GFCI's today. It is looking for equal amounts of current on the hot, returned to the neutral. If some of that "neutral" current is going via the EGC than that would be seen as a fault by the GFCI, assuming a greater than 5mA difference.

Close but no cigar. Its tied together at the box not the outlet. The outlet or gfi is looking in its self, not down the road.

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[Jaramie_Wilson]

A fault is NOT trying to return to earth, it is trying to return to it's source which in this case is the PoCo transformer, the fault will take all paths which the earth is one path.

Hum.. not what I was talking about. A fault is any current not on its intended path. Electric current seeks a complete circuit. When electricity is "used" its returned on the neutral (at ground potential because of connection to ground) the current is dissipated along all the ground rods on the system then what is left is dissipated at the substation grounding grid.

Everything is grounded in the end. Exempt the phase a b c. Witch loves ground wires.


Back on track.

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[wyliesdiesels]

Hum.. not what I was talking about. A fault is any current not on its intended path. Electric current seeks a complete circuit. When electricity is "used" its returned on the neutral (at ground potential because of connection to ground) the current is dissipated along all the ground rods on the system then what is left is dissipated at the substation grounding grid.

Everything is grounded in the end. Exempt the phase a b c. Witch loves ground wires.


Back on track.

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U sound like an electrical engineer.

Sorry but this isnt right.

Electricity from Lightning will dissipate into the earth but NOT electricty that is sourced from a power grid.

Norcal has been an electrician for many years. He know what hes talking about.

Electricty returns to its source.

Yes you may see electricty going through ground rods or electrodes at a residence but it doesnt dissipate into the earth. Instead it returns to the center tapped bushing on the transformer via the ground rod at the base of the pole.

 

[Jaramie_Wilson]

What you are saying is there's no need for a grounding system. No substation ground grid, ground rods or a system neutral. It all returns to the transformer thats powering it. Correct?

I would like you to take a light buld and socket out to your ground rod. Unhook it from your house. Run a hot to one side of the socket, a wire from the other side to the ground rod. Bolt it down, do not get in between it with the buld energized. (Dont complete the circuit with body) See if it lights up. Did the return current dissipate in to the ground?

50% or more of the return current is dissipated in to the earth before it hits the substation. This is why people have been killed steeling copper off of poles.

Loads that are intended to operate on 120v connect from the center tap to one of the secondary line. The function of the neutral is to carry the the difference in current between the two secondary lines and maintain a balanced voltage. I e one phase 24A the other got 30A the cebter tap is outputting 6amps. To keep it at 120v, if not the transformer will have lopsided (110/13o)voltage an you will have bigger problems.

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[wyliesdiesels]

No Im not saying that we dont need grounding systems. But you keep talking about grounding systems on the primary sides of grids.

The earth is can actually be a poor conductor of electricity depending on the condition of the soil.

The grounding electrodes' main purpose on residences is to disipate the electricity from lightning.

U also keep saying that electricity from the grid dissipates into the eath via ground rods. When neutral return current flows over rods, it doesnt dissipate into the earth, it travels through the earth to the ground rod at the pole, then goes up the GEC on the pole to the center tap bushing on the transformer. However, most neutral return current flows over the service drop neutral and not the rods.

But u keep referring to PoCo primary transformer grounding. I think U are confusing different types of grounding.

Im assuming youre talking about 'single wire earth return' primary wiring. Again though, the electricity on these systems doesnt disipate into the earth it travels through the earth back to the primary transformer's grounding electrodes.

https://en.m.wikipedia.org/wiki/Single-wire_earth_return

Grounding is one of the most misunderstood things.
Heres a good read for you:

http://www.electriciantalk.com/articles/the-confusion-of-the-term-grounding/