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Ask Kevin Your Own Question
Kevin, Licensed Electrical Contractor
Category: Electrical
Satisfied Customers: 3399
Experience:  30 years Licensed Electrical Contractor in Illinois, Adjunct College Electrical Instructor, Former Electrical Inspector, Diploma: Digital Electronics, FCC Technician License
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Kevin, Little confused still on a 220 oven outlet. OK

Customer Question

Hi Kevin, Little confused still on a 220 oven outlet. OK problem was I was mixing up the white conductor with it being neutral but rather it's a ground conductor, right? Again, this is two hots and the ground (old wiring). So if that 3rd conductor is the
ground is the oven grounded to that so that 3rd conductor is acting as an equipment ground? The reason I'm asking is that I extended the conductors and had to use metal j-boxes but don't have an equipment ground to ground them. So can I use the 3rd conductor
to do that by somehow splicing into it? Or should I run a separate green colored ground wire to each metal box but not sure of the AWG? Stove wire is 8 AWG.
Submitted: 2 years ago.
Category: Electrical
Expert:  Kevin replied 2 years ago.
Hello and welcome to Just Answer. My name is ***** ***** I will be happy to assist you with your electrical question.

1) Is this a new receptacle installation or an existing receptacle?

2) Is the receptacle a 3 prong type?

3) How many insulated house wires in the wall box? 1 black and 1 white or other colors?

4) Does the house wiring also contain a bare copper ground or a bare stranded wire?

5) Is this a new range installation? Does the range require a neutral conductor? Can you provide me with the manufacturer name and the range model number?
Customer: replied 2 years ago.

Hi Kevin, this is Dean from Oregon.

Updated my subscription so had to ask a new question.

I'm extending that old 3 wire oven outlet. The receptacle will be 3 prong.

House wires 1 black 1 red and 1 white. No bare copper.

Expert:  Kevin replied 2 years ago.
Hey Dean,

Didn't recognize your new name.

1) OK, the black and red will land on the double pole breaker.

2) The white neutral lands on the neutral bus bar.

3) The black hot lands on the "X" or "Y" of the receptacle. The red lands on the "X" or "Y" of the receptacle. Doesn't matter which hot lands on the "X" or "Y".

4) The white neutral lands on the "W" of the receptacle.

5) The receptacle should be a NEMA rated 10-50R, 3 prong receptacle for a range. Since you have 8 AWG conductors, the double pole breaker will be a 40 amp.

6) You will need a 3 wire cord from the range to the receptacle.

7) See the diagram shown below for the cord connection:

Black from cord lands on left side of range screw terminal. Red from cord lands on right side of range screw terminal and white neutral lands on the middle screw terminal.

Wire a Range <a href=Power Cord for 3Wire and 4Wire Cords" title="Wire a Range Power Cord for 3Wire and 4Wire Cords" width="232" height="300"/>

8) Since the receptacle does not contain a ground wire, you will need to jumper the green ground screw to the middle neutral screw terminal. There should be a jumper strap.

9) Since the house wires do not contain a separate equipment grounding conductor, code allows the neutral to be bonded to the dryer frame via a jumper. The metal JBox does not require a ground since no ground exists in the circuit. However, if you want to run a separate ground wire, you can use a 10 AWG Copper, Green insulated and then use a NEMA 14-50R, 4 prong receptacle and a 4 prong cord. If installing a separate ground, then the neutral is NOT bonded at the range frame. The green ground will land on the range frame green ground screw.

Reply back with any questions.
Expert:  Kevin replied 2 years ago.
If installing the 10 AWG ground wire, then the metal JBox and receptacle (4 prong) need to be grounded.
Customer: replied 2 years ago.

Kevin, what does a jumper look like from the neutral ground screw to the green Ground screw on the jbox?

If I ground that metal J-box where the receptacle is going into and

since I have another metal jbox above connected via FMC do I have to ground that metal j-box too even though it's bonded via FMC to the receptacle j-box that will be grounded?

Expert:  Kevin replied 2 years ago.

1) The jumper or bonding strap is a copper strap located on the back of the range where the cord terminations are made. If a bonding or jumper strap is not available or is missing from the range, then a short green insulated 10 AWG Copper wire can be used.

See pic shown below:

2) JBoxes don't have or use a jumper strap. JBoxes only use a green ground screw or a green grounding clip.

3) Flexible Metal Conduit is only allowed to NOT have an equipment ground if the FMC is 6 feet or less in length and if the branch circuit is 20 amps or less.

If the FMC is greater than 6 feet in length and/or the branch circuit is greater than 20 amps, then an internal equipment grounding conductor within the FMC is required.

4) If you ever come across a 3 prong electric dryer receptacle, the same code requirements as an electric range are also applicable. On a dryer circuit where no equipment ground exists, the neutral is also bonded to the dryer frame. Identical as a range. Electric wall ovens and electric cooktops are also the same when a 3 wire circuit was installed and no equipment ground exists. These are the only 4 appliances that the NEC allows bonding the neutral to the appliance frame. This is only allowed for circuits installed prior to 1996. After 1996, these appliances must have a 4 wire circuit........2 hots, 1 neutral and 1 equipment ground.

FYI........Code also allows the use of Service Entrance cable (SE) installed prior to 1996 where only 2 insulated hots and 1 stranded (non-insulated) neutral exists and no equipment ground. SE is the only cable that allows the neutral to be non-insulated. The exterior sheath of the SE cable is insulated. SE cable installed prior to 1996 can only be used on these 4 types of appliances. Any other cables require an insulated neutral.

Let me know if this helps Dean. Reply back with any questions.

Customer: replied 2 years ago.

Hi Kevin,

Since no ground in the circuit the metal boxes won't be grounded but if I run a separate 10 AWG ground copper wire green insulated wouldn't it be prudent to run it into each metal box and ground the boxes and then to the back of the receptacle? That would be cheaper (I think) then buying new 3 wire plus ground 8 AWG and running through the house to the oven.

And if I run a new ground wire would I have to run it through the FMC on my extension that I used to extend the circuit a few feet? Don't have any more room in FMC.

I notice in the list of 4 items you didn't mention water heaters. I wonder why they wouldn't want the neutral bonded to the frame of the water heater ( on a 3 wire circuit prior to 1996)?

Oh, also how long can my ground wire be? Is there a limit of length?

Expert:  Kevin replied 2 years ago.

1) Yes, if installing a ground, NEC allows a separate ground wire to be installed that would run parallel to the existing cable and would be more cost efficient than purchasing new 3 wire plus ground (4 wire cable)

2) A 240V electric hot water heater does NOT use a neutral, only 2 hots and 1 equipment ground. Usually a 30 amp double pole breaker with 10 AWG Copper conductors (3 wire circuit)

3) NEC allows an exterior equipment grounding conductor to be installed parallel to FMC and ziptied to the FMC but only for a maximum of a 6 foot length.

Customer: replied 2 years ago.

I don't know why I keep thinking that water heater cable has a neutral and not a ground. I haven't taken it apart yet but it looks like the owner has it loosely connected to the top of the water heater. I don't know where the ground wire is going but there is no connection to the green screw. So if I wanted to correct it for them I would just redo the connection and secure the wire connector down but also run the ground wire to the green screw?

Expert:  Kevin replied 2 years ago.
Ground wire sizing is based on by the number of amps on the circuit. The NEC has a table to size the ground based on the breaker size that serves the circuit.

If hots and neutrals are required to be increased due to voltage drops, then a ratio calculation must be performed by comparing the original circular mils of the branch conductors to the required branch conductors that will compensate for the voltage drop. No limit on length, but a limit on the wire size due to any voltage drops on the circuit.

When installing an equipment ground in a raceway, the ground wire size follows the NEC table for the largest branch circuit in the raceway.

For example a 3/4" PVC conduit contains 3 a 15 amp, a 20 amp and a 30 amp. In this example only one 10 AWG copper equipment ground is required in the raceway since the size is based on the largest circuit which is 30 amps in this example.

Yes, the ground wire connection on the water heater will be located at the same area where the 2 hots terminate at. There will be a green ground screw in this area.
Customer: replied 2 years ago.

Thanks ol' buddy! Smile

Back to my question about using the ground wire with the green wire cap with the hole inside of a metal j-box. I notice you mentioned twisting the grounds together with one of the ground wires going very long coming out of the hole of the green wire cap, connecting to the green ground screw on the j-box then connecting to the device.

Now is that the required way to do it or can I actually wrap the ground green ground screw first with one of my ground wires then twist them together with the green wire cap then onto the device?

For me it's actually easier to do it that way.

Also, is there any code on what type of j-box I can use in an attic? I used a metal single gang receptacle j-box and put one of those thin metal blank cover plates on it. Now the blank cover plate isn't as durable as the ones used for a 4" j-box. Hopefully the inspector is going to mind?

I might of brought this up before but just wondering what the inspector might do. Again, the previous owner used the octagon metal j-boxes with no wire/romex connectors in the openings of the j-box and mixed the old 2 wire romex (no equip ground) with newer 12-2 romex. I wonder if the inspector is going to flag all that in the attic and makes us re-run all new romex in those circuits? We're thinking about install in GFCI breakers on those circuits with no equip ground and mark the outlets appropriately like we did last time.

Expert:  Kevin replied 2 years ago.
1) Your method of twisting the ground wire is fine.

2) As long as the box is accessible and does not violate the box fill ratio (too small of a box for conductors and splices), you are good to go.

3) Where metal boxes are used, code requires Romex to have the proper box/cable connectors. Inspector will most likely catch these so best to install the cable connectors to the knockouts.

4) GFCI breakers or GFCI receptacles will work where no equipment ground exists. Yes, label the non-grounded receptacles accordingly.
Customer: replied 2 years ago.

Hi Kevin,

We talked about this long time ago regarding how many romex I can cram into a tight space. Well this is a little different in that I used 3/4 inch EMC and went about 4 feet using two 12-2 romex. Just wondering if there is a restriction?

Expert:  Kevin replied 2 years ago.
If the EMT is only being used as a sleeve to provide protection and does not contain any boxes or conduit bodies as a complete conduit system, then OK. However, a fitting is required on the end of the conduit to protect the cables from abrasion. A 3/4" box connector with a threaded plastic bushing is commonly used as abrasion protection. See pic shown below:

Customer: replied 2 years ago.

Hi Kevin:

Yes I did use the bushings. :) The EMT is coming down from the ceiling of a basement wall to a switch box (2 romex inside) then down from the switch box to a receptacle with just one romex inside.

Expert:  Kevin replied 2 years ago.
Very good.
Customer: replied 2 years ago.

Have a customer that wants a can light instead of the octagon J-box I put in for a standard light fixture. Never installed a can light before but doesn't look overly complicated. The bad news is that the sheetrockers already put the sheetrock up.

My question is how can I now install a can light? Would I just cut an opening away from the existing j-box and reach up into the rafters (it's in a basement ceiling) remove the current j-box and drop the can light into the hole after I enlarge it? Then connect the wires?

Or is there an easier way without cutting a big hole next to the current j-box?

Expert:  Kevin replied 2 years ago.
Home Depot or Lowe's also sells Remodel types of can lights specifically for your application. Cut out the drywall hole diameter and then de-install the existing box. Connect the cable(s) to the remodel can light and splice. Insert the remodel can light back to the hole and secure the fixture to the ceiling drywall via the side clips. An easy project. See link shown below:
Customer: replied 2 years ago.

Thanks Kevin! Nice tip. Smile

Also, I have to run romex in a garage from the ceiling of the garage down to near the floor and have to go through a rim joist about 4" thick. Should I use EMT then into a j-box and out through the back of the j-box into a hole in the rim joist? If so, would I not use any kind of bushing out the back of the j-box as the romex goes through the hole of the rim joist?

Expert:  Kevin replied 2 years ago.
If only (1) one NM cable, just bore a hole thru the center of the joist. Maintain a proper bend radius (minimum of 5x the NM diameter) on the NM if making any 90 degree bends.
Customer: replied 2 years ago.

Hi Kevin:

I have three romex cables but can drill multiple holes so perhaps 1 hole per romex. So if romex is 1/2 in width hole should be 5X or 2.5 inches in diameter? That seems like a huge hole for 1 NM cable at 90 degree bend? Can put more than one thru that hole?

Expert:  Kevin replied 2 years ago.
NEC allows a maximum of (2) two cables per single hole without being derated. If more than 2 cables, then the NM cables must be derated. Therefore, install 2 cables in one hole and separate the 3rd cable by a few inches into a 2nd hole. Thus no derating is necessary in this fashion. The bend radius will not be inside the hole, it will be located outside of the rim joist hole either going vertically or horizontally. Therefore, one NM cable should only require a 5/8" diameter hole or so. Yes, a 2 1/2" bend radius is required. Bend radius is required so the cable does not become pinched and destroying the exterior insulation and/or sharp bends on the conductors.
Customer: replied 2 years ago.

I know we talked about derating cables in the past and if I recall correctly you found that if the hole is over 3-4 feet long?

I was tearing apart a kitchen wall and found some interesting wiring. Whoever wired the outside light had the hot going to the light and the neutral going down to the switch. So switching the neutral connection was turning off/on the light! Don't believe that is correctly done. Should always be the hot that is tide to the switch and never the neutral?

Expert:  Kevin replied 2 years ago.
1) NM cables are derated if more than 2 cables entering the same hole or if a group of bundled cables entering a hole and greater than 24" in length. 2) Neutrals have not been allowed to be switched or fused since the 1930's if I recall. Only the hot conductor is allowed to be switched. About the only exception that I'm aware of is when using a transfer switch on a bonded neutral generator, then the 2 hots and the neutral are switched to prevent backfeeding into the public utility grid during a power outage when using a portable or a standby generator. 3) Keep in mind that NM Romex white conductors are allowed to be used as a hot feed conductor on switches as well as being used as traveler wires on 3 and 4-way switches. The white conductor can also be used as a hot conductor on a double pole circuit breaker for 240 volt circuits. If the white is used in any of these examples, the white must be re-identified as a hot conductor using black electrical tape or black paint or a black sharpie marking. Tape is the preferred method. Must be re-identified at both ends of the white conductor. This would apply to any manufactured cable such as NM Romex, MC (Metal Clad) cable or Armored cable such as BX. Same rules would apply on manufactured cables where the white is being used as a hot conductor and not as a true neutral. A white can feed a switch, but the switched loop out of the switch must be a different color such as black or red. Unfortunately, many DIYer's and even electricians do not re-identify the white using black electrical tape. I don't trust anybody when it comes to a white conductor as I always have my Wiggy available to test. Shared neutral circuits should also be labeled in my opinion, but code does not require the shared neutral to be labeled as a Multi-Wired Branch Circuit. I've been zapped many times years ago on a shared neutral and I no longer trust any white wire as being a true neutral:) 4) Code also requires a white neutral for all wall switch boxes or the "means" to have a future white neutral pulled into a wall switch box. Reason being is that many Occupancy Sensor switches require the neutral to provide a 120 volt for the Occ Sensor LED light. In this example, the neutral is still not switched, only the hot conductor is switched but the Occ Sensor needs the neutral in order for it to work.
Customer: replied 2 years ago.

Yes, definitely the white was the switched. I did a test to see if the hot coming into the light was always on and it was. House is probably around 1930s but their was intermixing of later made romex (white 12-2) with the circuit so I'm sure it was rewired at a later time.

When I use the neutral as a hot a make sure I mark it with black tape on both ends thanks to your fine instructions from the past. :)

Good reminder to not trust a white wire as a neutral. I'm developed a habit to always test my wires with my wireless voltage tester to make sure they're not live.

Side note my wireless voltage tester the kind you pay about $10 bucks for goes off way to easy even if I'm a 1.5 feet away from a live wire. Makes it difficult to see if a wire is really live unless I turn off all circuits near the one I'm working on. My other one was much better but the batteries were too expensive. What kind do you use that is not so sensitive?

Have great weekend. :)

Expert:  Kevin replied 2 years ago.
Very good on taping the wires. I have a variety of testers on my van and tool Contact and Non-Contact types, volt and clamp-on amp meters. I mainly use my Wiggy (contact solenoid type) Thanks Dean......have a great weekend as well!
Customer: replied 2 years ago.

Hi Kevin:

Bought a Sperry non-contact tester with sensitivity adjustment. Not sure if I like it. When setting is lowest no beep even directly put on live wire. Set the sensitivity too high beeps on dead wire. So have to calibrate it before using it and seems a waste of time. Not sure if I trust them now. I use my multi-meter to be sure. What one would you recommend?

I think I asked you this before but can't remember the answer: how high is the refrigerator outlet? I think you said there is no code on that but you recommended a height. Would you suggest same height as the other outlets that are above the countertop?

Expert:  Kevin replied 2 years ago.
Hello Dean, 1) I have a few non-contact testers, but I have not used them in probably 25 years. They are OK for a quick check on K&T wiring, but that's about it. Non-Contact testers sense voltage based on inductance (magnetism). Non-Contact testers can easily provide false indications since they can sense voltage from another working within the same box. Over the years, I've worked with numerous electricians and I've never seen any of them use a non-contact tester. The preferred voltage tester for electricians is a solenoid Wiggy tester as the 1st choice and a digital clamp-on amp meter and voltmeter as the 2nd choice. The Wiggy is a great testing instrument since they vibrate as well as show the, 240, etc. Some also have a light indicator. I rarely even look at the voltage indicator, especially if I'm working on 120 volt circuits. I just listen for the vibration:). On a Wiggy, you can even test and trip GFCI receptacles. No need for a GFCI 3-prong tester with a push button.Shown in the link below is a Wiggy voltage tester. tradename is ***** ***** Wiggy, since it was invented by a guy named WiggintonSee link below: Reason for only using contact testers is that electricians don't trust a non-contact tester:). Contact testers provide real time measurements and indications. Non-contact testers can provide false indications. For every day use, I always have my Wiggy readily available. They are much sturdier than a digital volt meter in the event they fall off of a ladder. I have a Wiggy that my dad used in the Navy during WWII and it still works great. They are also not as expensive as some volt meters. I only use a volt meter when I need to know exact voltage. 2) There is no code requirement on the height of a fridge receptacle. I install mine at 3 feet (3') above the finished floor. Countertop height will also work as that provides approximately a 3 ft 9 inch (3'-9") height above the floor.
Customer: replied 2 years ago.

Hi Kevin, it looks like your Wiggy has to come in contact with the bare wire to see if it's live or not? So you have to disconnect the wire, IE, from the wire nut, and put your probe on the bare wire to see if it's live or not? Or can you just touch the sheathing of the wire to see if live or not?

I want to find a more reliable way than those darn non-contact testers. Like you said I don't trust them either.

Expert:  Kevin replied 2 years ago.
Yes, A Wiggy is a contact tester and must come in direct contact with the wire or at a screw terminal.

No, touching the exterior sheathing when using a Wiggy will not work.

Depending upon the quantity of insulation that was removed at a wire nut splice, often, the pointed Wiggy probe can be inserted into the wire nut in order to make contact with the copper wires. Really depends upon the splice though.
Customer: replied 2 years ago.

Yo Kevin:

Hope you're weekend is going well. :)

On the rough in inspection I need to tuck the wires back into the j-boxes but do they need to be separated out such as grounds together, neutrals together and hots together or can I just have the wires for each romex tucked in separately which makes more sense to me?

Saw a something on a website that on the most common mistakes during a rough in inspection and one of those was: "NM cables installed less than 7 feet from attic access and not protected guard strips." Now is that a issue? I will be creating an attic access to the attic that is on the sides of the house with a bedroom in between.

Expert:  Kevin replied 2 years ago.
Hey Dean,

Weekend is good here. Hope yours is also.

1) I always tuck the un-needed wire groups into the back of the box and only leave the hot, neutral, switched loop and/or grounds and I install a plastic wirenut on the future needed conductors. Thus, all that is needed for the final trim out is to terminate the appropriate conductors on to the devices and/or lighting fixtures and remove the wire nuts. Bare copper grounds should be installed and tucked away 1st towards the back of the boxes.

2) Yes, code requires that NM Romex be protected at the attic scuttle hole opening using guard strips (wooden furring strips) within 6 feet of the opening access panel. Sandwich the NM Romex in between 2 furring strips where the NM Romex is laying across the floor joists. This will now protect the NM Romex from any items that may be stored on the attic floor joists.
Expert:  Kevin replied 2 years ago.
Shown in the picture below is the most common method to protect NM Romex cable around the 6 foot perimeter of the attic scuttle hole opening using furring strips:

... for running nonmetallic sheathed cable above a ceiling in the attic
Customer: replied 2 years ago.

what if the romex cables are right below the entrance to the door running right to left as you walk in? I have about 7-8 romex cables as you step thru the door over a 12" wall (the door is not floor level) and into the attic?

Now if the cables are running parallel to the joists do I not need any kind of protection?

Expert:  Kevin replied 2 years ago.
If the cables are installed on top of the joist's directly below the 12" knee wall, still requires guard strips.

If the cables are secured to the sides of the joists, then guard strips are not required.
Customer: replied 2 years ago.

If I have about 8 romex wires very close together running along the knee wall, would I just put a guard strip around this bundle? SO one strip then you have your 8 cables then another strip?

Expert:  Kevin replied 2 years ago.
Yes, that is correct Dean. You can maybe use a couple of furring strips or even some 2"x4"'s to box the cables in for the short distance. Thus creating a short channel path to protect the cables.
Customer: replied 2 years ago.

You mentioned earlier "NM cables are derated if more than 2 cables entering the same hole or if a group of bundled cables entering a hole and greater than 24" in length."

So if I have 3 romex cables going through a 2x4 then into my panel are they derated and by how much? IE 12/2 romex.

Also, if the cables are going through a 1/2 plywood and more than 2 cables is there any derating occurring?

Expert:  Kevin replied 2 years ago.
Just drill 2 separate holes and route 1 cable into 1 hole and the other 2 cables into the other hole. Then no derating is required.

If just providing protection on the cables using furring strips or boxing them with some 2"x4"'s, just leave a sufficient amount of space around the cable bundle and then no derating is necessary. The way around the derating factor is to have some amount of spacing available around the bundle or cable group.