Wrench97
Well-known member
Years ago the neutral and ground buss were the same, I believe it was the late 60's early 70's that changed to have separate neutral and ground buss bars.
Need help with 220v oven wiring
- Thread starter Joe From NY
- Start date
3 wire stove and dryer receptacles like the 10-50 were only allowed to originate from the service panel, where the neutral and ground buss are the same.
SGKent
Banned
Bert - what happens when say the guy's wood shop is on a sub-panel and some of the saws, planers etc are 240V. Say they use a NEMA 6-20 plugs and receptacles, or are wired straight into the device. Does it simply use 2 legs and a ground with no neutral? My question comes from an early argument over whether the 3rd wire was a ground or neutral. On a sub-panel the ground and neutral are separate so it can't be both.
6-20 is 240v only so no neutral, 2 hots and a ground.
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exranger06
Well-known member
Like I said before, appliances/machines that are 240V only do not need or use a neutral. Therefore, the 3rd wire is a GROUND, and it gets connected to the ground bar, not the neutral bar.
SGKent
Banned
thank you all for answering that. It makes sense.
wyliesdiesels
Well-known member
Stoves and dryer circuits didnt used to have a ground wire because ground wires didnt exist until the 60s. Before then, the circuit neutral was used as the ground as well. But this was only allowed on main service panels where theyre one in the same because the neutral bus is bonded.
Fixed it for you!
not quite.
Theyre still the same in a MAIN service panel AND existing subpanels in DETACHED structures.
subpanels in the same structure as the main were always required to have an isolated neutral bus.
And since 2008, subpanels in detached structures are required to have isolated neutrals.
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ard
Well-known member
You need to tear it all apart anyway...but...
If you turn off the breaker(s) do you still get 25V between the box and the neutral (white)?
If yes, if you turn off OTHER breakers, does it ever go away?
If you turn off the breaker(s) do you still get 25V between the box and the neutral (white)?
If yes, if you turn off OTHER breakers, does it ever go away?
OP
Joe From NY
Well-known member
The panel box in the church has the neutral and ground blocks both bonded to the box, and each has an assortment of ground and neutral wires mixed up and screwed into each one. the blocks are used interchangeably there, it seems.
OP
Joe From NY
Well-known member
OP
Joe From NY
Well-known member
This is the 10 gauge wire in the ceiling feeding the wall receptacle.
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James-W
Well-known member
I don't understand why you don't just run a new 4-wire cable and get it over with. Even if you do find the problem and somehow fix it, what have you really gained? Wouldn't it make a whole lot more sense to replace the old cable with a new 4-wire cable so that it will meet current code?
A picture of the main panel ground and neutral bars would be interesting to see based on your above comment.
Also take a pic of Stove nameplate to confirm proper size wire and cb to use.
AntonLargiader
Well-known member
That pic is your reminder that the orange wire is noncompliant all by itself (Romex not allowed on drop ceiling), regardless of what the actual problem is.
What code prohibits the use of nm-b above a drop ceiling? I have seen it used many times in the past on jobs that have been inspected. It would certainly be prohibited if the ceiling space is used as a return for the HVAC as it's not plenum rated but what prohibits it otherwise? I think in this case it would be prohibited anyways in a place of assembly.
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AntonLargiader
Well-known member
334.12 A2 "Exposed within a dropped or suspended ceiling cavity [except in residential]."
EDIT: and from stuff I read back when this thread started, I got the impression that the church kitchen doesn't necessarily count as a place of assembly. But as I have almost certainly never been in this particular church, I can't say for sure.
EDIT: and from stuff I read back when this thread started, I got the impression that the church kitchen doesn't necessarily count as a place of assembly. But as I have almost certainly never been in this particular church, I can't say for sure.
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Interesting, our shop was built in the late 90's and the office areas are all wired with nm-b above the drop ceiling, I've seen the same in other buildings as well. An exemption for residential makes sense or it wouldn't be possible to use a drop ceiling to finish a basement.
Does the place of assembly count for the whole building or just certain rooms? What would have to divide them ?
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wyliesdiesels
Well-known member
Is this main service panel for the building? IE does it have a meter on it or is it the first panel or disconnect AFTER the meter?
If not then thats a huge violation as neutral should NOT be bonded in subpanels that are in the same structure as the main service panel. This is a shock hazard.
This is the 10 gauge wire in the ceiling feeding the wall receptacle.
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Can you provide a pic of the nameplate on the stove?
If it requires a 50a circuit, then #10 NM-b is too small. Run a new circuit with the appropriate cable which for a drop ceiling and place of assembly, would need to be #6 MC or 6-6-6-10 in pipe....
AntonLargiader
Well-known member
My Googling indicates that it is per room, but that's just Googling. Haven't looked at the code.
James-W
Well-known member
The local churches around here have a doorway into their kitchen, and then there is a very wide "window with no glass" opening in the wall between the kitchen and the dining area with a large counter top to serve food on. I have no idea what the opening poster's church has for a kitchen, but if it is anything like they have around here, I would say the kitchen area is a place where the congregation assembles for varies reasons. Sometimes for a funeral, or for a wedding, or a baptism, etc, anytime they serve food.
Wrench97
Well-known member
Sounded like it was in the basement under the church no?
AntonLargiader
Well-known member
"...buildings or portions of buildings or structures designed or intended for the gathering together of 100 or more persons..."
OP
Joe From NY
Well-known member
OP
Joe From NY
Well-known member
Here is the requested view inside the main service panel
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OP, You have a different problem than I was expecting based upon a previous response where you indicated neutrals and grounds landed on the ground bars.
This panel appears to be a sub-panel as there is no main present. I also don't see a bonding screw between neutral blocks and enclosure.
A disconnect upstream of this panel would be considered the main panel. Or maybe there is another panel feeding this one.
The panel in these pics has ground wires landed on the neutral bars. There are no ground bars present. This is a safety issue as the conduit is carrying current back to the main panel.
This panel appears to be a sub-panel as there is no main present. I also don't see a bonding screw between neutral blocks and enclosure.
A disconnect upstream of this panel would be considered the main panel. Or maybe there is another panel feeding this one.
The panel in these pics has ground wires landed on the neutral bars. There are no ground bars present. This is a safety issue as the conduit is carrying current back to the main panel.
strutaeng
Well-known member
Yes, agreed. I'm no electrician, but the way the conduit "could" carry current or become energized is "if" the neutral becomes disconnected. That's the reason the code addresses this, but I thought it was how things were done once upon a time.
I watched this video to help me understand the concept.
I would consult a qualified electrician for recommendation.
That's one way you describe.
Another way is if a bonding screw were used in the subpanel, then both neutral and ground carry the imbalance between the hot legs. The imbalance current will split until the same voltage drops are reached on both paths based upon the resistances of each path back to the main neutral bar.
For the Op's situation, the imbalance current will flow to the neutral bar from each ckt. However, The ground wires from the mc cables attached to the neutral bar may also provide smaller alternate paths back to the mc jacket/panel enclosure/conduit to the main panel neutral bar if the ground wire were terminated in a metal box at the end of the mc cable. Also any contact points the mc cable then makes with grounded objects provide other return paths.
GFCI's trip at ~ 6ma. Leakage in the 10 - 50mA range can kill someone given correct conditions. These unintended return paths by other than with the neutral can easily support 10ma.
Neutrals are supposed to carry sustained intended currents from planned loads. Intended ground paths are only to provide short-term fault current to trip cb's. Unintended grd paths should not exist.
OP
Joe From NY
Well-known member
I think the three wires entering the box from the bottom are the main feeds. There is no upstream box.
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I think the three wires entering the box from the bottom are the main feeds. There is no upstream box.
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They are the the main feed to this panel but wherei is the main disconnect ?
OP
Joe From NY
Well-known member
Right below it where it comes in underground from the street. I’ll get a shot of it this week.
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wyliesdiesels
Well-known member
If there is a disconnect before this pictured panel, which there should be since there is no disconnect or main in this panel, then the pictured panel IS a subpanel and the neutral bar should be isolated. Also the ground wires should NOT be landed on neutral bars
dcg9381
Well-known member
Agree with wyliesdiesels.
It appears to be pretty easy to break out the grounds in this box with 2 ground bars.
Unsure however - if broken out, there is no Grounding Electrode Conductor present... So should the grounds be pulled off the neutral in this case.
It appears to be pretty easy to break out the grounds in this box with 2 ground bars.
Unsure however - if broken out, there is no Grounding Electrode Conductor present... So should the grounds be pulled off the neutral in this case.
If this is a sub-panel (I hope it is, but TBD), then it would not have a Grounding Electrode Conductor if the main panel were in the same building. If the main were in another building, then this sub-panel needs a disconnect and connection to a grounding electrode system.
The ground wires should be put on new ground bars. Not an option for a sub-panel. The conduit can serve as the equipment grounding conductor if complete point to point.
AntonLargiader
Well-known member
Did you mean to say there is no Equipment Grounding Conductor? That's the one that lets you split the grounds from the neutrals.
dcg9381
Well-known member
Largely, I'm asking if you isolate the neutral on this (pictured) panel and split off the grounds, what are we grounding to up-stream? I'd expect to see a ground wire to the main and within that main, something (eventually) connected to a ground rod...
(off the top of my head)
(off the top of my head)
The neutral blocks in this panel are isolated from ground.
It is the ground wires that need to move off of the neutral (only) block.
New ground blocks would attach to the panel enclosure
The panel enclosure would be considered grounded through the conduit connecting it back the next panel upstream.
An equipment grounding conductor is not required if the conduit provides ground continuity back to the source, but having it also is not an issue.
At the location where the neutral/ground bonding means exists (main panel or equivalent), this is the location where the grounding electrode system should connect.
Once the main panel is reached, the neutral block should be bonded to the enclosure.
dcg9381
Well-known member
Got it... Totally understand and agree.
Got it. But (maybe I missed it) the conduit to the main appears to be PVC, which doesn't carry current, so I'm expecting a ground wire. If it's metallic, I get it.
Around here, for the panel to be considered to be grounded, it had to be attached with metallic conduit and the rings that tighten that conduit also had set screws for ground wires... Maybe a newer code? That's how I built mine...
Understood neutral and ground bond at the main.
Got it. But (maybe I missed it) the conduit to the main appears to be PVC, which doesn't carry current, so I'm expecting a ground wire. If it's metallic, I get it.
Around here, for the panel to be considered to be grounded, it had to be attached with metallic conduit and the rings that tighten that conduit also had set screws for ground wires... Maybe a newer code? That's how I built mine...
Understood neutral and ground bond at the main.
I believe the conduit is metallic and hopefully rigid if in the pour. It also has a metallic bushing on it.
If it were pvc, then it's AFU. They would have needed to pull an egc.
Looks like the conduit passes thru a concentric ko. It should have a bonding bushing on it.
metlmunchr
Well-known member
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- Sep 10, 2011
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In the 20 or so years I worked in my dad's hvac business, I saw more scary wiring in churches than all other locations combined.
I did the hvac on a 20K sq ft addition to a large church in the late 80's. There were a couple existing offices in a hall behind the sanctuary where we extended the new hot and chilled water piping and added fan coil units.
Plans showed to pick up 120V circuit for the units from a sound room across the hall. The contractor who we'd subbed the power and control wiring to comes and finds me on the job one day to go with him to look at the sound room.
Never seen anything like it before or since. Surface mounted panel with no dead front or cover anywhere in sight. A mix of romex and SO cord thru knockouts with no connectors. Wire on the floor and draped over shelves. If they needed a couple more feet to reach, they'd just wire nutted a couple pieces together and kept on going on. Outlets consisting of loose handy boxes, also with no connectors to secure the cord or romex. The electrician had asked the custodian when he unlocked the door who did the electrical work in the room. A church member who was an engineer took care of all that stuff.
Electrician says no way he'd doing one minute of work in that mess. I agree. Says there's a panel about 75 ft away that has some spaces and couple pieces of empty pipe stubbed above ceiling level. I told him to go ahead and use that and that we'd just act like we'd never been in the sound room to avoid ******* anyone off.
Couple weeks later I'm walking thru the job with the local electrical inspector as he was checking off stuff associated with our part of the work. I mentioned the stuff we'd seen in the sound room as it was a major safety issue in my opinion. He says there's similar stuff all over the church that this same clown has cobbled up, but the guy's a buddy of the town mayor and anytime he's written anything up at the church, it just seems to disappear. He said he just hoped the building was empty when it burns, as he's convinced its just a matter of time.
About a year later, I turn on the TV one morning and there's a reporter on site showing the smoldering remains of the church. Fire chief is interviewed and he says they don't know the cause but it appears to have started somewhere near the front of the sanctuary. Couple months later, there's a small article in the paper saying the state fire people have determined faulty wiring in the vicinity of the sound equipment is the most likely cause of the fire. Fortunately, the building was empty at the time.
I did the hvac on a 20K sq ft addition to a large church in the late 80's. There were a couple existing offices in a hall behind the sanctuary where we extended the new hot and chilled water piping and added fan coil units.
Plans showed to pick up 120V circuit for the units from a sound room across the hall. The contractor who we'd subbed the power and control wiring to comes and finds me on the job one day to go with him to look at the sound room.
Never seen anything like it before or since. Surface mounted panel with no dead front or cover anywhere in sight. A mix of romex and SO cord thru knockouts with no connectors. Wire on the floor and draped over shelves. If they needed a couple more feet to reach, they'd just wire nutted a couple pieces together and kept on going on. Outlets consisting of loose handy boxes, also with no connectors to secure the cord or romex. The electrician had asked the custodian when he unlocked the door who did the electrical work in the room. A church member who was an engineer took care of all that stuff.
Electrician says no way he'd doing one minute of work in that mess. I agree. Says there's a panel about 75 ft away that has some spaces and couple pieces of empty pipe stubbed above ceiling level. I told him to go ahead and use that and that we'd just act like we'd never been in the sound room to avoid ******* anyone off.
Couple weeks later I'm walking thru the job with the local electrical inspector as he was checking off stuff associated with our part of the work. I mentioned the stuff we'd seen in the sound room as it was a major safety issue in my opinion. He says there's similar stuff all over the church that this same clown has cobbled up, but the guy's a buddy of the town mayor and anytime he's written anything up at the church, it just seems to disappear. He said he just hoped the building was empty when it burns, as he's convinced its just a matter of time.
About a year later, I turn on the TV one morning and there's a reporter on site showing the smoldering remains of the church. Fire chief is interviewed and he says they don't know the cause but it appears to have started somewhere near the front of the sanctuary. Couple months later, there's a small article in the paper saying the state fire people have determined faulty wiring in the vicinity of the sound equipment is the most likely cause of the fire. Fortunately, the building was empty at the time.