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Electricity!; or, How To Not Burn My House Down and Murder Myself

CptHamiltonCptHamilton Registered User regular
So when I bought my house several years ago it was serving as the development's model home with an office built into the garage. We had them convert the garage back into a garage, as part of which they 'unhooked' the ductless HVAC unit mounted on the garage wall. I use quotes as their unhooking amounted to pulling the wires out of the distribution box and physically cutting the cable going from the external AC unit to the wall unit. I never bothered about it because I didn't have any especial need to have AC in my garage.

Well, now I have a large furry dog who abhors crates and can't be trusted to run around loose indoors alone all day. It promises to be a very hot summer, so I figure some AC would make his life more pleasant on very hot days. Problem is, I have never wired anything into mains power before and I don't want to die.

The power supply cables attached to the external unit contain wires which are distressingly indistinguishable from one another but I have an ohmmeter on hand so I can presumably figure out which is which and hooking the external unit to the internal unit looks straight-forward. I've built electronics before so I'm not worried about the technicalities or reading the diagrams. But I've never done anything with one-phase power at housing voltages.

So we come to the crux of my question(s):

The power distribution box on the side of my house. It has 4 posts plus a ground post. There are 4 wires coming into it from...wherever the house mains wiring is coming from. A bare ground wire, a black wire, a white wire, and a red wire. My intuition would expect the red wire to be hot and the black to be neutral. Dunno what the white wire would be.

However!

The red wire is just capped and not attached to anything. The black and white wires are connected to the two posts labeled LINE. Nothing is connected to the posts labeled LOAD. This leaves me wondering what the red wire is for. Perhaps there are two hot wires for when one wants 220V?

The AC unit requires a ground connection and two power connections, labeled L and N in the diagram. It's my understanding that the L here is 'Live' and the N is 'Neutral', so once I figure out whether the white or black wire is hot (presumably the white?) I guess I connect the appropriate wire to the LOAD post beside the appropriate LINE post?

I'm further given to understand that it is standard practice to determine your hot wire using a contactless voltage probe. I don't have one, but I do have a multimeter. Am I going to explode myself (or at least kill my meter) if I attempt to measure voltage on the wire(s)?

Photo of the distribution box in question:
n7jlqxf5cg1v.jpg

PSN,Steam,Live | CptHamiltonian

Posts

  • ceresceres When the last moon is cast over the last star of morning And the future has past without even a last desperate warningRegistered User, Moderator mod
    For the love of God, hire an electrician.

    And it seems like all is dying, and would leave the world to mourn
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  • bowenbowen How you doin'? Registered User regular
    Yeah that is definitely the situation where an electrician would be the best use of $400.

    Ladies.
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  • bowenbowen How you doin'? Registered User regular
    Yeah that is definitely the situation where an electrician would be the best use of $400.

    Ladies.
    NocrenEncAngelHedgieSkeithDisruptedCapitalistzagdrob
  • davidsdurionsdavidsdurions Your Trusty Meatshield Panhandle NebraskaRegistered User regular
    Best double post I've seen yet. Just to emphasize: an electrician will come do this job quickly and safely. It's really the only reccomendation to be made until you are an apprentice electrician yourself.

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  • CptHamiltonCptHamilton Registered User regular
    I know I Could get an electrician and it would probably take them 5 minutes. It's just...it's three wires and one of them is completely non-dangerous. It feels so stupid to pay someone to attach the other two.

    But my wife agrees so I guess I'll call a guy.

    PSN,Steam,Live | CptHamiltonian
    firewaterwordNocren
  • FoomyFoomy Registered User regular
    I would stick with the electrician plan because you never know if things were correctly wired to that box or if it can handle the new amperage your going to pull on it.

    But for reference, if it was wired to code for North America white is always neutral, black is hot. Red can be used for a few things but is always hot, usually either a secondary for a 220V circuit, an outlet controlled by a switch, or for some multi-switch lighting circuits.

    Or in some cases the electrician ran three-wire to the outlet because that's what they had on hand and the red wire does nothing, but you cap it off anyway because leaving bare conductors in a box is bad.

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  • UsagiUsagi Nah Registered User regular
    And to be clear, "if it was wired to code" is a dicey possibility at best

    NocrenAngelHedgieGnizmoschusschrishallett83Tofystedeth
  • CptHamiltonCptHamilton Registered User regular
    Whether it was wired to code or not is iffy. But I know the box can handle the load as the unit in question was, in fact, wired to the box in question at one point in time.

    PSN,Steam,Live | CptHamiltonian
  • KakodaimonosKakodaimonos Registered User regular
    Is that a subpanel? You shouldn't be bonding the neutral and ground in a subpanel like that. You can only do that in the main panel.

    Usagichrishallett83
  • MulletudeMulletude Registered User regular
    I know I Could get an electrician and it would probably take them 5 minutes. It's just...it's three wires and one of them is completely non-dangerous. It feels so stupid to pay someone to attach the other two.

    But my wife agrees so I guess I'll call a guy.

    Good, because this was sounding like the setup to a Darwin Award

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  • EncEnc A Fool with Compassion The Land of Flowers (and Dragons)Registered User regular
    I know I Could get an electrician and it would probably take them 5 minutes. It's just...it's three wires and one of them is completely non-dangerous. It feels so stupid to pay someone to attach the other two.

    But my wife agrees so I guess I'll call a guy.

    If you hire an electrician and something goes wrong, you do not have liability according to most insurance companies. If you do it yourself, you do have liability and typically will not get as much, if any, award for damages. Home and renters insurance can vary greatly, but typically if you are doing a repair it is typically cheaper over time to have a professional do it and have ownership of blame if something goes horribly wrong.

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  • bowenbowen How you doin'? Registered User regular
    Is that a subpanel? You shouldn't be bonding the neutral and ground in a subpanel like that. You can only do that in the main panel.

    Yeah binding neutral to ground is how you end up with electrified pipes and shower drains.

    Ladies.
    Usagi
  • CptHamiltonCptHamilton Registered User regular
    It is a subpanel, I didn't wire it (it came that way when I bought the house...6 years ago?), and unless I'm missing something obvious here neutral is not bonded to ground. But presumably the electrician guy will say something whenever he comes out to plug wires in if I'm wrong.

    PSN,Steam,Live | CptHamiltonian
  • AngelHedgieAngelHedgie Registered User regular
    It is a subpanel, I didn't wire it (it came that way when I bought the house...6 years ago?), and unless I'm missing something obvious here neutral is not bonded to ground. But presumably the electrician guy will say something whenever he comes out to plug wires in if I'm wrong.

    And that's the whole point - there are so many questions here, it's just better to have someone who does this for a living look it over.

    XBL: Nox Aeternum / PSN: NoxAeternum / NN:NoxAeternum / Steam: noxaeternum
  • FoomyFoomy Registered User regular
    Is that a subpanel? You shouldn't be bonding the neutral and ground in a subpanel like that. You can only do that in the main panel.

    It doesnt look that way to me, the ground is going to a terminal in the middle of the box, the neutral is just ovetop of it in the picture.

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  • bowenbowen How you doin'? Registered User regular
    It did sort of look like it followed right behind it, but yeah you're right foomy.

    Ladies.
  • CptHamiltonCptHamilton Registered User regular
    Yeah, there's a ground terminal in the middle of the box, to which the ground line is attached. The cover for the panel has a diagram indicating that's how it ought to be. It's pretty easy to tell which wire is the ground since it's bare copper.

    PSN,Steam,Live | CptHamiltonian
  • Eat it You Nasty Pig.Eat it You Nasty Pig. tell homeland security 'we are the bomb'Registered User regular
    there are some home projects that can be done by laypeople who are either enthusiasts or want to save money; you can't really fuck up too badly resurfacing a floor or replacing a fixture and so on (well, you can, but the consequences are minor)

    this is not that kind of project; an easy mistake can have pretty serious consequences. Just hire it out

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  • AngelHedgieAngelHedgie Registered User regular
    there are some home projects that can be done by laypeople who are either enthusiasts or want to save money; you can't really fuck up too badly resurfacing a floor or replacing a fixture and so on (well, you can, but the consequences are minor)

    this is not that kind of project; an easy mistake can have pretty serious consequences. Just hire it out

    And by "pretty serious consequences" we mean "your home burning down".

    With you and your family in it.

    Electricity in large quantities demands respect.

    XBL: Nox Aeternum / PSN: NoxAeternum / NN:NoxAeternum / Steam: noxaeternum
  • ThroThro Registered User regular

    I'm further given to understand that it is standard practice to determine your hot wire using a contactless voltage probe. I don't have one, but I do have a multimeter. Am I going to explode myself (or at least kill my meter) if I attempt to measure voltage on the wire(s)?

    Well, the majority of the responses seem to dissaprove of you burning your house down, so that seems addressed.

    You can measure line voltage with multimeter. Not, super well but enough to tell if a wire is live or not. Pin on the wire in question, other one on ground or neutral. Trying to measure current, however, may cause damage to the multimeter (or blow the internal fuse it should have).

    Jebus314
  • GnizmoGnizmo Registered User regular
    It might seem silly to hire someone for a couple of wires. You know what is sillier? Calling an ambulance because of a couple of wires. Yes there is a chance that nothing goes wrong and you save money. There is also a chance you electrocute yourself and, at best, it hurts like a motherfucker. I would pay to not be shocked by a lot of house lines ever again. I would pay a lot.

    Usagi
  • CptHamiltonCptHamilton Registered User regular
    I found a friend of a friend who does residential wiring and had them walk me through it so that I could learn what I was doing. Turns out all my assumptions were correct and now I have a working AC unit. But I did almost wire a thing backwards so good to have had a professional on hand.

    PSN,Steam,Live | CptHamiltonian
    bowen
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