Upgrading 220V wiring - need professional advice!

[Opifex]

Hello,

This is a common question but answers seem to differ depending on who you ask. I am not looking for the "right" answer, but any and all acceptable answers. I have a decent understanding of terms (as might be found in the NEC) and DIY experience. I am in the middle of a kitchen remodel and need to make a decision. The new double oven, of course, will come standard with 4 wires. The wire coming into our 1966 house is, of course, a 3 wire SEC cable (two hots and one bare stranded aluminum, pictured below). I understand this wiring configuration utilizes a "bootleg" ground that is no longer code compliant and potentially risky (one might say potentially lethal), but still allowed under an exception. As a matter of fact, the new oven we are purchasing includes wiring instructions for a 3-wire system like mine.

In principle, I would prefer to replace the existing SEC cable for an appropriate 4-wire conductor, but DIY remodeling has its limitations. Here's what I know:

1. The sheathing of the existing SEC cable is in very good condition under the crawl space.
2. The run itself is no more than 25 feet and terminates at the main electrical panel and a 40 amp breaker. I opened the panel this morning and verified that the wiring appears to come in from the attic, which I don't quite understand because it first enters from the crawl space, but there you have it.
3. I'm unsure if I have an actual grounding rod, but I do have bare copper bonded to the galvanized pipes in the crawler. (NOTE: I have already replaced 75% of the galvanized pipe with PEX).

Now for my questions.

1. If I am not able to replace the existing SEC cable, could I simply run a bare copper EGC from the junction box to the electrical panel and call it good?
2. If solution #1 is not advisable, could I run the bare copper EGC to the same location where the galvanized pipes are grounded (as previously suggested in this thread), since presumably the existing copper EGC travels back to the electrical panel?
3. If neither solution will work, what do you all suggest?

 

[bigb56]

Hello,

This is a common question but answers seem to differ depending on who you ask. I am not looking for the "right" answer, but any and all acceptable answers. I have a decent understanding of terms (as might be found in the NEC) and DIY experience. I am in the middle of a kitchen remodel and need to make a decision. The new double oven, of course, will come standard with 4 wires. The wire coming into our 1966 house is, of course, a 3 wire SEC cable (two hots and one bare stranded aluminum, pictured below). I understand this wiring configuration utilizes a "bootleg" ground that is no longer code compliant and potentially risky (one might say potentially lethal), but still allowed under an exception. As a matter of fact, the new oven we are purchasing includes wiring instructions for a 3-wire system like mine. When you say "the wire coming into our house" which wire are you referring to, the one from the meter to the sub panel or from the sub panel to the range? Also please post a picture of your meter/main showing if it is just a main disconnect or another panel with more breakers. (If it is just a meter/main that makes the EQ load center your main panel which makes a difference in the rules)

In principle, I would prefer to replace the existing SEC cable for an appropriate 4-wire conductor, but DIY remodeling has its limitations. Here's what I know:

1. The sheathing of the existing SEC cable is in very good condition under the crawl space.
2. The run itself is no more than 25 feet and terminates at the main electrical panel and a 40 amp breaker. I opened the panel this morning and verified that the wiring appears to come in from the attic, which I don't quite understand because it first enters from the crawl space, but there you have it.
3. I'm unsure if I have an actual grounding rod, but I do have bare copper bonded to the galvanized pipes in the crawler. (NOTE: I have already replaced 75% of the galvanized pipe with PEX). Using water pipes for grounding is forbidden, however the metal piping in your house is required to be bonded to the main service neutral and to the grounding electrode system.

Now for my questions.

1. If I am not able to replace the existing SEC cable, could I simply run a bare copper EGC from the junction box to the electrical panel and call it good? This is somewhat of a gray area as the NEC says all conductors of a circuit must be run in the same cable or conduit, but in another part of the code it allows a grounding conductor to be connected to an accessible point on the grounding system.
2. If solution #1 is not advisable, could I run the bare copper EGC to the same location where the galvanized pipes are grounded (as previously suggested in this thread), since presumably the existing copper EGC travels back to the electrical panel? Maybe, depending on where that copper wire terminates at the other end.
3. If neither solution will work, what do you all suggest?

After your replies to the above I will reply with my recommendations as a career electrical contractor.

See replies in blue.

 

[Sponsor]

 

[Opifex]

Sorry for the confusion. I appreciate you taking the time to reply. I will take a picture of my electrical meter and update the post after I get home from work. The meter is on the side of my house, but I have only one service panel with a 200 amp breaker/disconnect. There are no subpanels anywhere on the property. The old oven was wired using the same 3-wire SEC cable that connects to the main (i.e., the "wire coming into the house" ).

 

[Opifex]

Meter:

 

[Reach4]

https://terrylove.com/forums/index.php?threads/4-wire-range-and-oven-to-3-wire-se-cable.88642/ may have some info for you. I cannot apply this to your situation.

 

[Opifex]

Thank you, I will check these links out!

Update: Yes, those older threads are on point. Reach4, your past suggestion about installing a 40 amp GFCI breaker is intriguing. That would obviously be a simple solution. If I did that, I presume I would still need to bond the EGC from the oven chassis to the neutral, per manufacturer instructions and NEC.

I was up in the attic yesterday and found the SEC cable run. It appears to exit the top blocking, take a turn, and from there go down again into a hole and then into the crawl space between finished drywall. Unfortunately, I don't think I will be able to fish a new 4-wire cable through all that.

 

[wwhitney]

I understand this wiring configuration utilizes a "bootleg" ground that is no longer code compliant and potentially risky (one might say potentially lethal), but still allowed under an exception.

The first part of this statement is not correct. It is allowed under an exception for existing installations, and as such is code compliant.

If I am not able to replace the existing SEC cable, could I simply run a bare copper EGC from the junction box to the electrical panel and call it good?

If you are able to run a new copper EGC from the panel to the junction box behind the oven, why can't you run a new 10/3 - 6/3 (depending on circuit rating) NM cable along the same path?

Cheers, Wayne

 

[Opifex]

Hi Wayne,

Thanks for the correction. Yes, I suppose it is code compliant after all, so I might just leave well enough alone. When I first noticed this issue, I became worried about the "potential" risks and comments, perhaps exaggerated, by electricians on the Internet. Maybe it's not really a significant safety issue. I have examined as much of the original SEC cable sheathing as I can, both in the attic and in the crawl space, and it appears to be in fairly good condition.

You're right about running a copper EGC to the panel. Realistically, I don't think that will be happening. So the only easy and realistic way of adding an EGC would be to connect to the iron pipe in the crawl space, but I don't think that is permitted by NEC 250.130(C). I'm pretty sure the existing bare copper bonded to the pipe terminates at the service panel.

 

[bigb56]

OK so the EQ load center is back to back with the meter which makes the EQ load center your first disconnecting means. You do realize that the EQ load center is a split bus right? When you switch off the one labeled "MAIN" it only shuts off the lower "lighting" section (starting with the furnace). The upper section always remains energized unless you pull the meter outside. You do have also have a violation in that the total disconnects cannot exceed 6 and someone put two single pole breakers in the upper section for the microwave and "shop?" making the total now 7 disconnects.

So the 3 wire SEU feeding the main panel is perfectly acceptable as that is your main service, and the grounds and neutrals not only can be connected there but they are required to be connected there.

I know this isn't what your question is but just wanted to put it out there. The whole reason is because you could run a 4 wire line to that panel legally since it is not a 3 wire sub panel, but rather a 3 wire main panel, although I realize in reading your initial post it may not be in the scope of this remodel.

The 3 wire SEU installed directly to the main panel with no stops along the way met all the code requirements at the time of installation (many did not) and is basically an extension of the main service. If it were mine I'd use it as is, bonding the neutral to the range cabinet. It still makes a very effective fault current path, better than a separate EGC added after the fact as I will explain below.

If you choose to add an EGC you will compromise the trip curve of the circuit breaker because when the EGC is not in close proximity to the line conductors you risk a delayed trip which, if even a second or two can have serious consequences. The SEU can turn into an arc welder and I have personally seen a $125,000 fire that started when an AC breaker didn't trip fast enough because it was using an alternate grounding path. I was actually on site when this happened and you could hear the cable arcing in the wall for several seconds igniting attic materials and causing major smoke damage and a hole in the roof from the responding firemans' axes who arrived in just a couple minutes.

I would only run a separate EGC in a case like a wall outlet in a brick wall where a new cable couldn't be run. With the 3 wire SEU you already have a dependable fault current path so I wouldn't screw with that, you'll be trying to fix something that isn't broke so to speak and may end up with a less efficient grounding means.

The ideal situation is a new 4 wire circuit to the panel which I would explore. You don't have to take the original route to get there. It may require some crawling in the attic or crawl space/basement and some drywall repair but that is the optimum solution. So that's my advice:

1. new circuit
2. use 3 wire circuit as is.

I would also replace the breaker with a new one since that one is pretty old and it may be slow to trip. Siemens is the brand you want for that EQ load center which BTW is a very decent load center. Be aware that the upper bus will be live all the time when the meter is installed!!

 

[wwhitney]

You do have also have a violation in that the total disconnects cannot exceed 6 and someone put two single pole breakers in the upper section making the total now 7.

Looks like that could be fixed by just adding a handle-tie?

Cheers, Wayne

 

[bigb56]

Looks like that could be fixed by just adding a handle-tie?

Cheers, Wayne

Yes a handle tie or just a new 2 pole 20. Handle ties are sometimes easier said than done.

 

[Opifex]

Thanks, bigb56! Very helpful. Yes, I am aware of the upper bus being energized. I will give some more though to adding a new 4-wire circuit as you suggest.

 

[Opifex]

I would also replace the breaker with a new one since that one is pretty old and it may be slow to trip.

Good idea, cheap insurance. Assuming it's compatible, what are your thoughts on using a GFCI breaker?

 

[bigb56]

Good idea, cheap insurance. Assuming it's compatible, what are your thoughts on using a GFCI breaker?

Not a bad idea, you could try it. NEC is now requiring GFCI protection on new installations at 240V and 240/120V locations up to 50 amps.

 

[wwhitney]

Not a bad idea, you could try it. NEC is now requiring GFCI protection on new installations at 240V and 240/120V locations up to 50 amps.

FWIW, per up.codes, Oregon (OP's state) uses the 2020 NEC but has amended 210.8(A) to still only apply to 15A and 20A 125V receptacles.

Also, in the unamended 2020 NEC, 210.8(A) applies to all 125V and 250V receptacles, with no amperage limit. Of course receptacles above 50A are pretty rare.

Cheers, Wayne

 

[bigb56]

FWIW, per up.codes, Oregon (OP's state) uses the 2020 NEC but has amended 210.8(A) to still only apply to 15A and 20A 125V receptacles.

Also, in the unamended 2020 NEC, 210.8(A) applies to all 125V and 250V receptacles, with no amperage limit. Of course receptacles above 50A are pretty rare.

Cheers, Wayne

Yes a lot of local jurisdictions have made amendments, but in the interest of safety I think putting a GFCI on the circuit, if possible, is a good idea to gain an extra layer of user shock protection.

 

[Opifex]

Agreed. I tried doing just that when I consolidated the dishwasher and garbage disposal (these are on separate 20 amp circuits, but the Romex was protruding from the drywall), but I could not locate the first receptacle in either circuit! I did find a black wire in one of the outlets that was not hot; the wiring seems to be wonky. I had to be content with a single GFCI protecting the dishwasher and the adjoining outlet (for the disposal) in the same electrical box.

I don't mind opening my work up to criticism. Behold:

Correction: They are not on separate 20 amp circuits (I know), but we rarely use the dishwasher anyway.

 

[Opifex]

I know what you're going to say: the box is not well placed, and I would agree with you.

 

[bigb56]

I know what you're going to say: the box is not well placed, and I would agree with you.

Hey, with older homes you do the best that you can.

 

[bigb56]

FWIW here is an AI overview using info from grounding and bonding geru Mike Holt's site of why the EGC should be run with the circuit conductors. Many Google results simply say that is is due to a longer path, but this helps in understanding what happens to the impedance of the EGC, and why the existing conductor will do a better job at fault clearing than adding a new one.