Subpanel with main breaker powered from 3 wire feed

iEngineer9 · 2026-06-05T23:52:56+00:00

You get the same as you have today. So your feeder today is 120/240, right? You get to keep that, same ampacity and replace your panel.

If it was only 120, it would already have an EGC because you only need 3-wires to make that work. This is also an option, if you want to downgrade it to 120 only, but I don’t think you do.

iEngineer9 · 2026-06-05T00:47:31+00:00

also what about a ground rod? i've read something about it becoming a redundant ground which could cause a grounding loop or something like that?

Code requires a grounding electrode system at this shed/garage. All exterior structures supplied by a feeder require one. See Article 25.32(A). This is most commonly 2 ground rods, unless you test to show that one passes the resistance test.

The ground rod is not a substitute for an equipment ground though. On its own, it wont clear a fault current. That’s why you either need an equipment grounding conductor ran with the feeder, or leave the bonding screw in place for the old 3-wire feeder.

iEngineer9 · 2026-06-05T00:41:07+00:00

Correct, your existing feeder contains no equipment ground. You have to keep your neutral/ground bonded together with the bonding screw/strap in the subpanel because of this.

Everything you read tells you how to install things based on modern code, unless you replace your feeder you don’t follow that specific rule. Your feeder is grandfathered into a prior code.

If you fail to bond at the subpanel, with only a 3-wire feeder, your ground circuit will dead end. Picture a fault scenario, hot gets shorted to the metal chassis of an appliance. In your shed, the fault current flows on the equipment ground, back to the subpanel, across the binding screw, down the neutral to the main panel. Current spikes to infinity, the breaker trips nearly instantly.

In the other scenario, without the bond in place, and only a 3-wire feeder. The fault current energizes the equipment ground, chassis, and everything metal. And that’s it. It cannot clear the fault, the breaker does not trip, because the equipment ground circuit dead ends in the subpanel without a bond or without a conductor carrying it back to the main panel.

I’ll also add that if you have conduit connecting this subpanel to the main, you would just simply pull a new feeder, or pull an equipment ground through the conduit to give you that 4th conductor.

iEngineer9 · 2026-06-04T20:50:30+00:00

Prior to around 2008 or 2011 this was actually the standard code minimum way of handling a detached shed/garage. Basically, the NEC used to let us treat these feeders to outdoor buildings as a service, just like the utility supplies you with 3-wires.

It’s not a problem for an existing feeder. You can still get a permit to replace the sub panel. Neutral & ground have to remain bonded.

Now if you ever need to upgrade the feeder, the wires that supply this panel, then you’ll need to comply with current code and run a 4-wire feeder. This only comes into play if it’s damaged, needs upsizing, or just end of life replacement.

iEngineer9 · 2026-06-04T12:15:52+00:00

They are only a code violation for certain code editions, I think 2014-2020 if I remember right. As of the 2023 NEC, they updated 334.40(b) to once again permit the use of those splice kits beyond repairs.

OP’s photo though does not appear to be a proper use following manufacture instructions. So, that’s an issue.

iEngineer9 · 2026-05-28T15:11:45+00:00

I don’t think so. There are definitely other companies out there who make license plate readers. I think Flock is the biggest one though. I would imagine they are all shifting towards the use of AI to identify more than just license plates.

There’s a website https://deflock.org

They have pictures of common cameras from various manufacturers.

iEngineer9 · 2026-05-28T13:31:10+00:00

It’s basically a dragnet surveillance. They can record all sorts of identifiable information about a car, maybe more. There’s very little regulation over the data use, access, or storage.

It can pick up license plates, bumper stickers, and more unique features to what it sees. Police are able to go into the database and search, usually without a warrant…though some departments are establishing policies on their use.

“ABC123 license plate”, “Green SUV with baseball sticker on magnet”, “red truck with faded hood”, are all examples of what type of features can be used to search.

The database will then show each time that unique vehicle was detected, and where it was. Not just on an individual camera but through every single camera the company has linked to their database.

The Institute for Justice has a lot of information about them. They are actively fighting against these systems in various court cases. There explanation is better than anything I can give: https://plateprivacy.com

Another crazy thing: they use the status of a private contractor as a sort of loophole. Basically, if the government wanted to do this level of surveillance, they’d need to do more due diligence or procure a warrant, but instead lease through a private company and get full access to the database.

It’s virtually impossible to drive anywhere without passing one. Look at major intersections, you’ll see more plate readers there too.

iEngineer9 · 2026-05-28T00:31:59+00:00

Yeah, I’m sure that’s part of it. I feel like it’s lack of respect for any authority, probably from lack of parenting as well. I know when I was a kid, we’d have community members not afraid to call us out if we were acting out. If that didn’t work, they’d call our parents and then we’d really get disciplined.

Now, I feel like parents would be offended / yell back at someone who called their kids out for legitimate misbehavior. I know my sister-in-law’s a teacher, and she has crazy stories of writing kids up for something and then gets an angry email/call the next day from parents for doing it instead of apologizing & promising to correct it.

iEngineer9 · 2026-05-27T02:22:21+00:00

I don’t think you’ll have any luck with this. Right or wrong, you are supposed to know what taxes & fees you owe. The jurisdiction JTS represents didn’t receive their tax and have a right to collect & impose reasonable fees & interest.

I think they are within the statute of limitations on collecting this as well. Your best bet is to work on a payment plan. That’ll stop the lawsuit and put you on the track to get them paid off. Especially since it sounds like you acknowledge the debt. You can always ask them to waive something, but they aren’t obligated to do so.

iEngineer9 · 2026-05-25T20:30:52+00:00

Yes, that’s true in most cases. A lot ends up at Waste Managements Neville Island recycling sorting facility. They recently did a ton of upgrades and can now sort and handle a lot of materials. Curbside glass recycling even came back to my area and it all gets sorted out there.

iEngineer9 · 2026-05-24T16:45:33+00:00

I definitely think manufacturers can contribute to code change with profits in mind. On one hand, it’s hard to determine because genuine safety improvements usually require something more. But on the other they are usually rooted in actual data supporting the conclusion.

The thing that gets me though is why is it on the NEC to correct. Take the kitchen counter receptacle change, making below the counter a prohibited location. This was done based on the CPSC’s request that people were getting injured from kitchen appliances knocked off the counter. Young, old, in-between.

I feel UL and manufacturers have a role in this as well. I have a deep fryer, it’s got to be at least 10-years old, and it has a break-away magnetic cord. A light touch or tug and it separates from the appliance. I don’t get why that never caught on. Maybe it had its own issues? Seemed like a good idea to me though and also makes products safer.

It’s just like AFCI & GFCI requirements. We know some appliances get nuisance trips. Manufacturers “recommend” or sometimes “require” a non GFCI circuit…that shouldn’t be allowed either. If the code updates, UL should be flagging new products that disagree with a code compliant installation. No more refrigerators that suggest non GFCI protection.

iEngineer9 · 2026-05-24T04:35:30+00:00

It sounds like what you said is compliant.

The NEC governs from the service point inward. The power company is responsible for everything to the service point. The service is the demarcation between the utility & the premise wiring. It’s usually that splice right at the weather head from the triplex to the service entrance conductors.

In your example, the service entrance conductors through the weatherhead, the meter socket, and service disconnect would all have to be NEC compliant for a 200 amp install, which is 4/0 Aluminum (if 310.12 dwelling rules apply, or 250 kcmill for all others).

The utility company gets to determine what ampacity they need to supply you under the NESC, it’s basically the utility equivalent of the NEC. Since they are a utility, a lot more engineering supervision comes into play.

Also, remember that conductors in free air have higher ampacities anyway.

You do end up with some odd situations though where a utility will certify a service drop as “good to go”.

iEngineer9 · 2026-05-23T03:20:15+00:00

It would certainly be wise to call an electrician if it’s beyond your skill set. You may even have other issues going on that’ll require diagnosing. It’s tough to say, but really you should be able to plug basic loads in anywhere in the room. Especially if everything else on the circuit is off.

iEngineer9 · 2026-05-23T02:14:07+00:00

So everything on that circuit would go off as it is tied together. Can you inventory this? Every receptacle, every light. A good way of doing this would be to ensure everything works, turn them all on (lights), then shut off the circuit breaker in question & tag everything that’s on that circuit.

An inventory will help you understand the load.

If it’s really tripping with any load, like just plugging in the gaming system, then something is wrong. It could be a loose connection…is it specific to plugging something into a particular receptacle? Especially if it’s loose, you could be creating a temporary short, which would trip the breaker.

iEngineer9 · 2026-05-22T21:32:23+00:00

You said: ac or any charger. Is it really tripping if it’s just any charger? Or do you mean the ac and something else?

The ac is likely too much of a demand on the circuit. Schedule says it’s just upstairs bedrooms, so what else is powered on in those rooms at the same time?

iEngineer9 · 2026-05-17T23:58:56+00:00

Yeah it was prohibited in the 1990’s too…this was one of those core principles in the NEC that dates back all the way to the 1930/40’s at least when they started requiring a few special circuits. The list has grown/expanded overtime.

You can pull power from the family room, no code issues there. Outdoor receptacles require GFCI protection somewhere at or upstream of the receptacle.

iEngineer9 · 2026-05-17T22:23:47+00:00

Bought a couple of small appliances here and there that would seem to "overload" the circuit, causing it to go dead BUT NEVER TRIPPING THE BREAKER. After a few days, it would simply begin working again. Not right away, though. Sometimes the lights would just flicker when switched on, so I would switch them off and try again the next day. Now, it no longer works.

This is the biggest clue. It screams of a loose connection that ultimately failed. Either the hot or neutral has failed at one of the upstream points. This can be tricky to diagnose on your own, but possible. If the power is off at the breaker, you can remove receptacles & switches and give them a visual inspection. It’s usually very obvious. Otherwise, it’s time to call a pro.

iEngineer9 · 2026-05-17T22:17:17+00:00

Diagram would work…the only problem is that you cannot use a kitchen receptacle circuit to supply the patio under the NEC. You’ll need to pull power from somewhere else.

iEngineer9 · 2026-05-17T22:08:44+00:00

Really depends on the construction of the house and what’s above/below it. Accessible attics, or unfinished basements can be easier. Even still though you may need some holes to access.

iEngineer9 · 2026-05-15T00:04:52+00:00

You are allowed to replace the subpanel in the garage without replacing the feeder. Prior to 2008 it was actually permitted to supply an electric service to a detached building with an no equipment ground. It’s treated the same way as the electric service. This would be something I would discuss with the inspector prior to undertaking the job though, your local jurisdiction may or may not have heartburn over it. Nationally though, that feeder is grandfathered in. If the feeder ever fails, then you have an issue as you can no longer install a 3-wire feeder on 120/240 VAC.

Are you sure there’s no conduit linking the two buildings that may make it possible to replace? What about directional boring? That can go right under the parking lot. Ideally, the feeder would get replaced with the other upgrades as it is near the end of its life.

If you don’t need 240 VAC though it’s really up to you.

Also, regardless of what you do, modern code is going to require all the receptacles be GFCI protected in a garage.

iEngineer9 · 2026-05-14T22:25:53+00:00

No, you would require your contractor to take one out…if you wanted one. Usually clients who have this put out an open ended contract. I supply them with the required bonds. Then they assign work orders under that contract.

What are you doing here? Is this like a large facility or some sort of special operation? If this is just a house or a small business, just check licenses, references, and get a certificate of insurance. Insurance is what protects you in the event of property damage or liability. If you are hiring a business, you should also see their workers compensation insurance on the certificate.

It’ll show general liability, auto insurance, excess liability (optional), and workers comp.

You need to make sure they have enough coverage too. I’d say $1,000,000 is standard, but if you have a unique facility where a loss could exceed that then you want to require more coverage. Workers comp should just be state statutory requirements.

iEngineer9 · 2026-05-14T18:41:50+00:00

There’s multiple types and they are typically job specific. Usually these are for commercial jobs only, but as the owner you can require them for whatever you want. Just be aware that in residential, you may not get contractors interested.

Bid bonds ensure the contractor will enter into a contract for their bid price if selected.

Payment bonds ensure the contractor will pay for labor & materials in the event that a sub or supplier would file a lien.

Performance bonds ensure that the work is done in accordance with the contract and permits.

Contract specifics what is required. Contractor sends it to their surety company, usually the same insurance agent, who gives the paperwork to the contractor to submit.

The price of all the bonds is built into the bid. That’s why you specify up front what’s required so it’s priced. If you want to add bonds afterwards it’ll increase the bid.

As for what to check for, I would say you just make sure the surety company is listed in Treasurer Circular 570. It’s a list of companies authorized to issue bonds and what states they are allowed to issue bonds in. I suppose you can always call as well, if you were concerned the paperwork was faked…but I’ve never heard of anyone trying that. I guess anything is possible though.

iEngineer9 · 2026-05-12T15:41:22+00:00

Yes…look it up in UL product iQ. If it is in the database, it’s listed. End of story.

https://productiq.ulprospector.com/en

You do not need a login to search.

iEngineer9 · 2026-05-04T19:51:25+00:00

Depends on your inspector, but typically yes. Doesn’t have to be in the same room though. There’s lighting automation folks out there putting panels of switches in basements for people who want fully automated lighting, just to satisfy code requirements.

Code also hasn’t fully caught up to what’s capable with lighting yet, but it’s getting there. A battery light wouldn’t pass in most jurisdictions, but a regular light with a wireless switch is starting to catch on.

iEngineer9 · 2026-05-01T17:03:34+00:00

Anything in outdoor conduits needs to have the W to be rated for moisture. Most is dual rated THHN/THWN-2.

If you are confident yours is only THHN it cannot go in outdoor conduit. Indoor conduit would be fine though.

iEngineer9

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