# Electrical wiring help please - GFCI wiring related **URL:** \ **Category:** Factual Questions\ **Tags:** tools-electric-diy\ **Created:** [April 16, 2023, 5:04pm UTC](https://boards.straightdope.com/t/electrical-wiring-help-please-gfci-wiring-related/982749 "2023-04-16T17:04:26Z")\ **Posts on this page:** 10\ **Page:** 4
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [April 20, 2023, 5:31pm UTC](https://boards.straightdope.com/t/electrical-wiring-help-please-gfci-wiring-related/982749/61 "2023-04-20T17:31:34Z")
> [@engineer\_comp\_geek](#): > > > [@OldOlds](#): > > > > Could I “leagally” run a single line to a sub panel in the unfinished part of the attic (no problem with access) and then “drop down” into the various second floor rooms from that sub? It would dramatically reduce the total wiring and the amount of smashie-smashie in the walls and ceilings. > > It’s generally not a good idea. The area around the sub-panel can’t be used for storage, and an attics are generally used for storage. Also, if there is a fire in the panel you won’t smell the smoke since it will rise. A fire in a basement or ground floor panel will be much easier to detect since anyone home at the time will much more quickly smell the smoke. > > That said, whether it’s legal or not depends on a bunch of things. > > The attic needs to be easily accessible. You say there’s no problem with access, but does it actually meet the NEC guidelines for it being an accessible space? If you need to pull down a ladder or otherwise climb into the attic then it’s probably not. If you have fixed stairs going into the attic then you are probably ok. > > Is there an adequate working space around where the sub-panel will be located? That space needs to be 6 1/2 feet tall, 3 feet wide, and 3 feet deep. A lot of attics don’t have that much unobstructed space where a panel can be located. You also need to have enough space so that the panel door can open fully. > > The area has to be well-lit, so you might have to install a light bulb near the panel. > > There is a limit to the size of the sub-panel (amp capacity). I don’t recall what the limit is off the top of my head but you’ll need to check that. > > There may be some other requirements but that’s all I can think of off the top of my head. Basically, if you can easily get into the attic and have the working space around where you want to put the panel, you’re probably fine. > > Since you are redoing everything, you’ll want arc fault interrupters (AFCI) in your bedrooms and ground fault interrupters (GFCI) in any “wet” locations (kitchen, bathroom, garage, etc). Basically, you can replace like with like (so if your house is old and has 2 pronged outlets and one breaks, you can replace it with a 2 pronged outlet), but anything you change has to meet all modern codes. Yes, good info. Install a pull-chain light fixture in front of the panel and a 120-volt wired smoke detector. Keep the space clear in front of the panel too. Also, readily accessible just means you don’t need “special” tools or methods to access. A pull down ladder is fine. Plenty of panels are located on mezzanines, in attics, locked closets, etc…I would highly recommend a subpanel if you follow the NEC. An electrician should assist with this for sure. My suggetions to you (or anyone here) are not intended to be all inclusive, but rather helpful guidance. YMMV and other disclamers YADDA, yadda. ---
**Author:** ![OldOlds](https://avatars.discourse-cdn.com/v4/letter/o/a3d4f5/32.png) [@OldOlds](https://boards.straightdope.com/u/OldOlds)\ **Post date:** [April 20, 2023, 5:35pm UTC](https://boards.straightdope.com/t/electrical-wiring-help-please-gfci-wiring-related/982749/62 "2023-04-20T17:35:28Z")
Oh. And as far as code violations go… Some time after we moved in, several things in the kitchen went out. I found no breakers tripped. I kept going back to the panel, thinking “I must be losing my mind” At some point the thought of a sub panel popped into my head. Sure enough, in the lower cabinet, to the right of the sink, behind a mess of pots and pans, there it was. And indeed still is. In all its 50s Murray glory. My kitchen sub. ---
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [April 20, 2023, 5:37pm UTC](https://boards.straightdope.com/t/electrical-wiring-help-please-gfci-wiring-related/982749/63 "2023-04-20T17:37:51Z")
Yup, seen that before. Illegal as heck, but often times installed as “the handyman special”. ---
**Author:** ![WolfpackJeep](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpackjeep/32/2921_2.png) [@WolfpackJeep](https://boards.straightdope.com/u/WolfpackJeep)\ **Post date:** [April 20, 2023, 11:43pm UTC](https://boards.straightdope.com/t/electrical-wiring-help-please-gfci-wiring-related/982749/64 "2023-04-20T23:43:18Z")
I’ve really enjoyed this thread! > [@Uncommon\_Sense](#): > > Plenty of panels are located on mezzanines, in attics, locked closets, etc… I was thinking this sounded a bit scary, and then I remembered where the panel was located in my college apartment – in the little locked utility closet that was only accessible via the patio. ---
**Author:** ![Snipe70e](https://avatars.discourse-cdn.com/v4/letter/s/51bf81/32.png) [@Snipe70e](https://boards.straightdope.com/u/Snipe70e)\ **Post date:** [April 21, 2023, 1:02am UTC](https://boards.straightdope.com/t/electrical-wiring-help-please-gfci-wiring-related/982749/65 "2023-04-21T01:02:35Z")
> [@OldOlds](#): > > I’ll be redoing a second floor bathroom in the next couple of weeks. May I make a suggestion. Put each bathroom outlets on a separate 20 amp breaker. And don’t just install one outlet for the sink counter top. In my last house I put in multiple double outlets on both sides of the counter top. There can neve to many outlets in a space and bathroom often get over looked with only a single outlet. so outlet multipliers get installed to plug in the hair dryer, more than one electric tooth brush, a lighted mirror, an electric heater. WE are going to redo our master bathroom this year. I have already installed a separate 20 amp double outlet for now. But when I get done my wife will have 4 places where she can plug things in on both sides of the sink. ---
**Author:** ![DavidNRockies](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidnrockies/32/6279_2.png) [@DavidNRockies](https://boards.straightdope.com/u/DavidNRockies)\ **Post date:** [April 21, 2023, 10:27pm UTC](https://boards.straightdope.com/t/electrical-wiring-help-please-gfci-wiring-related/982749/66 "2023-04-21T22:27:04Z")
I kinda’ like this guy. When his most recent video came up in my YouTube feed, I thought of y’all. If only for the estimable SDMB Knowledge Base … A bit over six minutes. [**I’M A VIDEO**](https://youtu.be/QeARueAfcI0) Also, when his upper screw (that secures the receptacle into the box) wouldn’t bite, a longer but similar screw was one option, but I also recently learned about, and used, these: > **[G-Clip - Quick and easy repair of stripped and broken plastic electrical boxes](https://www.g-clip.us/)** > > Do you have a loose electrical switch or outlet? The G-Clip eliminates the need to replace a damaged, plastic electrical box. Install the G-Clip by pressing it onto the edge of the electrical box, over the damaged hole. The G-Clip provides a new... FYI. ---
**Author:** ![Mean\_Mr.Mustard](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mean_mr.mustard/32/3865_2.png) [@Mean\_Mr.Mustard](https://boards.straightdope.com/u/Mean_Mr.Mustard)\ **Post date:** [April 22, 2023, 1:06am UTC](https://boards.straightdope.com/t/electrical-wiring-help-please-gfci-wiring-related/982749/67 "2023-04-22T01:06:14Z")
I like the video but I am not following one part of it. At the 3:00 mark, the guy touches one probe to the left lower white wire and the other to the right upper black wire and gets a reading of 0 volts. He then clicks the dial on the meter to a different setting, repeats the same probe/wire combo, and gets a reading of 50 volts. At this point he says “If you’re getting 50 volts on a non-loading meter that means that those two do not go together.” Can anyone explain what is going on here? Why would you get 50 volts? What does he mean by “those two do not go together”? Thanks, mmm ---
**Author:** ![DavidNRockies](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidnrockies/32/6279_2.png) [@DavidNRockies](https://boards.straightdope.com/u/DavidNRockies)\ **Post date:** [April 22, 2023, 1:25am UTC](https://boards.straightdope.com/t/electrical-wiring-help-please-gfci-wiring-related/982749/68 "2023-04-22T01:25:14Z")
That’s a great question. So, I studied Electrical Engineering in college … decades ago … but I never used it – went a different way. Meaning: I’m pretty sure I know what he’s talking about, but rather than me take a ham-fisted shot at explaining it … let me point out this web page: > **[Dual Impedance Digital Multimeters](https://www.fluke.com/en-us/learn/blog/digital-multimeters/dual-impedance-digital-multimeters)** > > Find out what dual impedance and voltage detection are and why it's good to have them built into your multimeter. Find out about impedance basics, ghost voltages, non-contact voltage detection and the absence or presence of voltage testing. I think the relevant section headings are: - The best of both worlds, and - What are ghost voltages and where are they encountered? I think the combination of those two sections explains what he’s making reference to. Basically, the ghost voltage, if present, can lead you astray, particularly if you have a high impedance only multimeter. Another good take on it: > **[Input Impedance - Electrical 101](https://www.electrical101.com/input-impedance.html)** > > Meters with a high input impedance draw almost no current through the meter while testing a circuit. It’s also akin to why a multimeter isn’t generally as good a battery tester as is a proper battery tester, which puts the battery under a precise load (or resistance, or impedance, roughly). ETA: one more analogy… The low-impedance (no load) reading might tell you if there’s standing water remaining in the garden hose. The high-impedance (load) reading would tell you if that water is under pressure. ETA2: and the “don’t go together” is his way of saying that the second common he tested – where it read 50VAC – is NOT the common that provides the return path for the hot that he tested (the upper black wire in the video). ---
**Author:** ![DavidNRockies](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidnrockies/32/6279_2.png) [@DavidNRockies](https://boards.straightdope.com/u/DavidNRockies)\ **Post date:** [April 22, 2023, 2:05pm UTC](https://boards.straightdope.com/t/electrical-wiring-help-please-gfci-wiring-related/982749/69 "2023-04-22T14:05:23Z")
This is a pretty good video on the issue of of ghost voltage and detecting it with a dual impedance multimeter. It’s content until about 3:30, after which it’s marketing for his affiliate links: [**YOUTUBE VIDEO**](https://youtu.be/JRXTFxsA_lA) ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [April 22, 2023, 2:33pm UTC](https://boards.straightdope.com/t/electrical-wiring-help-please-gfci-wiring-related/982749/70 "2023-04-22T14:33:22Z")
Yea, the high input impedance of the meter (when measuring voltage) will form a voltage divider with leakage resistance in the wiring, causing “ghost voltages.” To solve this problems, some meters have a “Lo Z” feature that allows the user to select a low input impedance. [Previous page](https://boards.straightdope.com/t/electrical-wiring-help-please-gfci-wiring-related/982749.md?page=3)