More fun electrical questions!

[Jeff7]

As I mentioned in a thread long ago, I intended to set up a little woodworking shop in one of the rooms of my apartment. The problem is, every single device wants a ground connection, which I wasn't expecting. Why is it a problem? There's only one grounded outlet in the room, and it won't support the current draw of what I need to run.

I've got a big vacuum cleaner, which, according to my Kill-A-Watt, draws 7.9A when running. (The KAW beeped when the vacuum started up, indicating a momentary draw >15A. :Q)
The wiring to the grounded outlet is 12/2, to a 20A breaker, and was just installed in September 2007.

Anyhow, with 8A devoted to the vacuum, that doesn't leave a whole lot to run power tools. The bandsaw alone is rated 8.8A, and likely will draw more than that, especially when it's trying to cut something.
Ideally I'd like to have the vacuum running anytime another device is being operated. Another note, the vacuum's hoses are dryer hose, which will either be entirely aluminum or old vinyl with a steel wire inside, so the hoses themselves will be connected to the vacuum's ground.

The other issue is, in the summer, the grounded outlet will be used to run a 6000BTU air conditioner.

So the question is, which is better, if either:

1) Keep the vacuum grounded, but let everything else run ungrounded.

2) Run everything ungrounded. (except the AC)


The floor is carpeted, covered with plastic, with waferboard on top of that, so it's not like I'd be standing on a wet concrete floor.
People survived use of electrical devices before ground connections were mandatory.

I have read that running one ground wire to multiple circuits is a bad idea, as the electricity can find some odd paths in some cases. That's why I'm wondering about option 1 - if one device is grounded, and it makes contact with something else, it might set up one of those funky ground circuit. I don't want to be vacuuming up the floor, holding the grounded hose, then touch the lathe and become a ground conductor.

Getting an electrician in isn't an option right now. My landlord spent $500 shortly after I moved in to get new circuits put in at my request (nothing was grounded before). I don't think I can ask him again to do something like that - I'd have to pay for the new work I'd want done.

 

[Eli]

You have it kinda wrong, the band saw should draw 8.8A at full load - considerably less than that with no load.

Also, if something isn't up to code, you most certainly can ask your landlord to fix it.

 

[Jeff7]

Well see, the vacuum is rated 6.2A, but the meter says 7.8A.
I'll check the bandsaw quick...

 

[BigJ]

Do yourself a favor and replace a couple of outlets on different circuits with a GFCI. As long as your neutrals are properly wired, you're fine.

A 3-pack will cost you about $28 at a home improvement store. They'll cost you about half that + shipping online.

 

[Jeff7]

Originally posted by: BigJ
Do yourself a favor and replace a couple of outlets on different circuits with a GFCI. As long as your neutrals are properly wired, you're fine.

A 3-pack will cost you about $28 at a home improvement store. They'll cost you about half that + shipping online.

I saw on one site that GFCI's weren't good for motors or large appliances. In the campus apartment, my electric razor tripped the GFCI about once a week just from turning it off or on.


Ok, the vacuum is rated 6.7 amps.

And the bandsaw is going to be a little while. For some reason, it's not turning on at all.
Bandsaw's working, more or less - the switch is a bit weird, probably just getting old. The good news: draw peaked at 6A cutting a 1" diameter branch. And damn that motor is in good shape, and the blade is great - it just glides through wood.
Still, I've got various other things, like a belt sander, and of course, the lathe's motor. When these things start up, they push 15A. I don't want to be tripping the breaker, because getting to the breaker box is a PITA.

Originally posted by: Eli
You have it kinda wrong, the band saw should draw 8.8A at full load - considerably less than that with no load.

Also, if something isn't up to code, you most certainly can ask your landlord to fix it.

I'm not sure how much he's actually required to do. It's an old building, at least 50 years old. (Upstairs, underneath the carpet in one closet, there was the front page of a newspaper from the 1960's.)
With old buildings, I don't know if you're required to bring anything up to code. The entire building would effectively need to be gutted and rebuilt. All of the wiring was 2-conductor.


This apartment is a fine example of "taking the good with the bad." It's an old building, the windows are a bit drafty (no way to find that out when signing the lease in the summer), and it's a bit far from campus. But I don't have noisy neighbors, and it had a lot of space for the cost of rent. Noise was one of the major factors that drove me off campus. I've heard from other people who live in apartment complexes, and some of them have really loud neighbors.
I think next winter, if I'm still here, I will definitely get some of that plastic film for the windows. The instructions say to apply it outside, and to do so when the temperatures are above 50F. The wind chill is negative today, and I think if I'd take a walk, I'd get blown halfway across the state. (It's really goddamn windy out there.)

 

[BigJ]

Originally posted by: Jeff7

Originally posted by: BigJ
Do yourself a favor and replace a couple of outlets on different circuits with a GFCI. As long as your neutrals are properly wired, you're fine.

A 3-pack will cost you about $28 at a home improvement store. They'll cost you about half that + shipping online.

I saw on one site that GFCI's weren't good for motors or large appliances. In the campus apartment, my electric razor tripped the GFCI about once a week just from turning it off or on.


Ok, the vacuum is rated 6.7 amps.

And the bandsaw is going to be a little while. For some reason, it's not turning on at all.

For smalltime work like you're doing, GFCIs are fine. If you were running 220v shop tools, I'd change my mind.

Think of it this way. How many people have you known to have shops in their garage? Well guess what, almost all (with a few exceptions) receptacles must be protected by a GFCI in garages.

 

[feralkid]

Originally posted by: Jeff7
The entire building would effectively need to be gutted and rebuilt.

To re-wire?


Not likely.

 

[Squisher]

Couldn't he also use a GFCI plug in with a 2 prong adapter?

Expensive, but wouldn't require you to do any electrical work.

 

[Jeff7]

Originally posted by: BigJ
For smalltime work like you're doing, GFCIs are fine. If you were running 220v shop tools, I'd change my mind.

Think of it this way. How many people have you known to have shops in their garage? Well guess what, almost all (with a few exceptions) receptacles must be protected by a GFCI in garages.

I have known only one person to have a shop in his garage: my uncle. He built it himself, and the entire thing was wired as well as a house, and properly grounded. And insulated. And climate controlled. It's a nice garage. He got ripped off by too many auto shops, so he does almost all the work on his car himself, and he wanted a nice place in which to do it.

Sounds like I'll just stick a GFCI in one outlet, label it according to code, and plug in.
I'd love to add a circuit myself and run the wire, just as an interesting project, but 1) I need to learn how to wire a breaker box, not that that seems too difficult to do, 2) I don't know how to run wire through a wall, though I've got a few ideas, 3) more money, 4) landlord would likely want to supervise, and I don't know that he's got the time.

Originally posted by: feralkid
To re-wire?


Not likely.

Not just that. Remove old drywall, with water damage in one spot due to a leaky roof, the latter of which has since been repaired. Strip off lead-based paint from various walls and repaint. Put in better insulation and vapor barriers. Replace ancient single-pane, untempered-glass windows. Renovate bathroom. Replace dishwasher. Replace old dryer. Replace old washer - I don't know when it was built, as the metal tag with all relevant information has been worn flat from decades of use, but the manual was copyrighted in 1973.
Etc etc etc.

It's an old, old building. Best option as far as I'm concerned: demolition + reconstruction.

 

[zig3695]

i happen to be a licensed jorneyman for the residential electrical trades... what i would do? well, you could use that grounded outlet's ground, and extended it to another circuit, but it wouldn't be exactly code. and furthermore you would want to make sure its on the same power bus (a or b). that is because when youll run your a/c and other inductive loads youll get some sort of current back on the ground wire (not many appliances are balanced perfectly across the hot wires), and if you mix phases up youll heat up that ground too fast.

so the easiest and probably your best route for now is to install GOOD gfci outlets in your home, as already mentioned. you dont have to do them all, but surely for the ones being most used. theyre gonna cost at least $10 a piece... $20 for the good ones and if your running motors on them, youll want good ones trust me. Mind you, installing gfci's doesnt give you a ground, but it does let you plug grounded cords into the wall and still have a fairly sensitive, mechanical saftey switch on it. they say its about as safe as a real ground circuit, and there are reasons for both sides to make a case. i like the real thing myself, but gfci's absolutely do save lives.

ps- i almost forgot. since your outlets dont have grounds, they also likely are not physically big enough to fit a full gfci protected outlet in them. in that case youll probably will just end up getting those 'adapter' kind that have two prongs that go into the existing outlet, and have a 3 prong grounded female side to plug your stuff in. easy to install but i like them even less then the in-wall type, but again if thats all that you can use, its much better then no ground at all.

 

[BoomerD]

Your SAFEST option would be to have a licensed electrician come in and wire in a panel and outlets for your shop equipment. While he's there, have him wire in a proper outlet for that A/C unit...

 

[olds]

This is starting to sound like too much work.

 

[spacejamz]

you have a bandsaw and a workshop in your apartment??

pics??

and noisy neighbors drove you further from campus? don't bandsaws and shop tools make a lot of noise? am I missing something?

 

[0roo0roo]

wear a dust mask.

 

[Leros]

Originally posted by: spacejamz
you have a bandsaw and a workshop in your apartment??

pics??

and noisy neighbors drove you further from campus? don't bandsaws and shop tools make a lot of noise? am I missing something?

I was wondering that myself. When I lived in a house, I could hear a neighbor all the way across the alley using power tools. I would be very pissed if somebody in my complex used power tools.

 

[Analog]

Originally posted by: zig3695
i happen to be a licensed jorneyman for the residential electrical trades... what i would do? well, you could use that grounded outlet's ground, and extended it to another circuit, but it wouldn't be exactly code. and furthermore you would want to make sure its on the same power bus (a or b). that is because when youll run your a/c and other inductive loads youll get some sort of current back on the ground wire (not many appliances are balanced perfectly across the hot wires), and if you mix phases up youll heat up that ground too fast.

First, the ground wire should never have any current on it. It is meant as a fault path for safety purposes.

In most residential applications, it is a single phase system. perhaps you meant between the 240V sides to neutral. That is, the electrical panel has two sides, each representing a side of a center tapped transformer. Each side is 120V to the center tap, which is the neutral. This is all single phase. The neutral, or center tap, is tied to ground at the electrical panel. From there on out, the ground should never have any current on it normally.

Polyphase panels (2 or 3) are generally used for larger buildings, businesses etc. Usually resulting in 208V panels in three phase applications, which have 208V/(sqrt(3)) to ground, which is ~120V, or 208V phase to phase. etc. There are also 277V yada yada yada. All of which don't apply here.

That being said, it would probably be okay to use the same ground wire to multiple outlets, since it is daisy chained in a new application. The question is, how good is that ground to begin with.

 

[Jeff7]

Originally posted by: spacejamz
you have a bandsaw and a workshop in your apartment??

pics??

and noisy neighbors drove you further from campus? don't bandsaws and shop tools make a lot of noise? am I missing something?

I don't have any neighbors.

The building started out as a residence, but was partly cut in half some years ago, with part of the turned into a general store/deli, and the other half contains the original kitchen and livingroom. There is good isolation between the two halves - I can't hear the store, and they can't hear me.
It's certainly not a complex; it's more like I've rented a house. Two bedrooms upstairs, a nice kitchen with space for a dining table (the previous tenant was so kind as to leave her table and chairs here), a livingroom, and off of the kitchen is a small room which qualifies as a walk-in closet. Within that, is another section, underneath the stairs, which is a genuine closet. What was formerly the porch has been completely enclosed, and now houses the bathroom and laundry appliances.

Originally posted by: zig3695
i happen to be a licensed jorneyman for the residential electrical trades... what i would do? well, you could use that grounded outlet's ground, and extended it to another circuit, but it wouldn't be exactly code. and furthermore you would want to make sure its on the same power bus (a or b). that is because when youll run your a/c and other inductive loads youll get some sort of current back on the ground wire (not many appliances are balanced perfectly across the hot wires), and if you mix phases up youll heat up that ground too fast.

That's the sort of thing I would definitely want to avoid. Crossing grounds sounds like risky business.

so the easiest and probably your best route for now is to install GOOD gfci outlets in your home, as already mentioned. you dont have to do them all, but surely for the ones being most used. theyre gonna cost at least $10 a piece... $20 for the good ones and if your running motors on them, youll want good ones trust me. Mind you, installing gfci's doesnt give you a ground, but it does let you plug grounded cords into the wall and still have a fairly sensitive, mechanical saftey switch on it. they say its about as safe as a real ground circuit, and there are reasons for both sides to make a case. i like the real thing myself, but gfci's absolutely do save lives.

I'll probably just do one to start with. That ought to be all I need. It's not like I'll be running 4 things at once - just the vacuum and one, possibly two, other devices. Lighting is all on separate circuits, and those are CFLs anyway.

ps- i almost forgot. since your outlets dont have grounds, they also likely are not physically big enough to fit a full gfci protected outlet in them. in that case youll probably will just end up getting those 'adapter' kind that have two prongs that go into the existing outlet, and have a 3 prong grounded female side to plug your stuff in. easy to install but i like them even less then the in-wall type, but again if thats all that you can use, its much better then no ground at all.

I'll have a look at the boxes and how they're mounted. If I have to, I'll buy another box, if that's what you're referring to. Installing that sort of stuff isn't difficult at all.

I did minor renovations on half of the basement back in my parent's house. Tore down old paneling along the concrete wall, put up new furring strips, insulating foam, and a moisture barrier, things that the old wall lacked. I also put paneling over the old drywall, ran some wire for new ceiling lights, and rewired several outlets, complete with conduit.
A guy we've had do that sort of work in the past had to stop by to replace the water heater, and he looked over my work and gave it his seal of approval.

Basic electrical wiring: not too difficult at all.

Originally posted by: BoomerD
Your SAFEST option would be to have a licensed electrician come in and wire in a panel and outlets for your shop equipment. While he's there, have him wire in a proper outlet for that A/C unit...

The AC unit does have a proper outlet. As I mentioned, there is one good, new, properly grounded outlet in the room.


One GFCI: simplest option, and I think that's what I'll go with for now.
When/If I get a job that lets me have some extra cash, then I'll talk with my landlord about adding yet circuit. It should be a bit easier for the electrician, as there's already a new wire running to that room. He should be able to loop onto it, and slide the new wire right along it. If I have a job that nets me a LOT of extra cash, then I'll probably move out and find something that was built after the Bronze Age.


Analog - how good is the ground? I don't know. It was a licensed electrician who installed the new wires, so I'm hoping he knows what he's doing, and my super high-quality Walmart-bought circuit tester says that the outlet is grounded; a backup power supply also says that it's properly grounded. I know that that evidence is about as solid as Britney Spears' psyche, but, you know, it's all I've got.




Pics will be posted.........eventually.

 

[zig3695]

ehh, yeah i was implying he would use the existing circuit as a 240v feed for his a/c.... i wasnt even thinking that he probably has a 120v unit. im on a lot of vicodin today sorry....

 

[Jeff7]

Originally posted by: zig3695
ehh, yeah i was implying he would use the existing circuit as a 240v feed for his a/c.... i wasnt even thinking that he probably has a 120v unit. im on a lot of vicodin today sorry....

I think one 240V unit would be enough to cool my entire apartment.
I've got 1 8000BTU unit for downstairs, and a 6000 for upstairs. I'd probably have to go to 12000 to need 240V.


Hopefully you're not drugged up when you're working.

"Izzere power in thisherething? Lemme jus lick it quick..."

 

[MikeyIs4Dcats]

why are you grounding vacuum hoses?

 

[Squisher]

Originally posted by: MikeyIs4Dcats
why are you grounding vacuum hoses?

Central vacuum units for woodworking are huge sources of static electricity. Sparks are not something you want around a cloud of saw dust contained in a confined space like a vacuum tank. Think BOOM!

Originally posted by: oldsmoboat
This is starting to sound like too much work.

Originally posted by: Squisher
Couldn't he also use a GFCI plug in with a 2 prong adapter?

 

[Jeff7]

Originally posted by: MikeyIs4Dcats
why are you grounding vacuum hoses?

They're grounded by virtue of the construction of the hose system - they plug into the vacuum, and the wires within the vinyl hoses wind up making a connection to the coffee can "plugs" on either end - or when they wear out and I start using the aluminum dryer hoses (I think vinyl has been phased out for that, as it's a fire hazard), then I'll have one big conductor.

Yes, static can be a BIG issue for this sort of thing. Before I had that big metal vacuum up there, I was stuck using an upright Eureka vacuum - all plastic casing, and no grounding prong. Remember how iron filings look when sprinkled over a magnet, and those on the poles all stand up on end? That's how the sawdust on the hose and vacuum body looked. I could get some half-inch sparks from touching grounded metal objects. I think it's the same thing that lets a Van de Graff generator build up its charge.



Squisher - thanks for those links. I didn't know that that was the sort of thing you meant, or that those things even existed. Snazzy.
Still, I'll likely just go with a regular GFCI outlet. For the same price, I get two outlets instead of just one, and no extra little thing to worry about losing.

 

[jagec]

Originally posted by: Analog

Originally posted by: zig3695
i happen to be a licensed jorneyman for the residential electrical trades... what i would do? well, you could use that grounded outlet's ground, and extended it to another circuit, but it wouldn't be exactly code. and furthermore you would want to make sure its on the same power bus (a or b). that is because when youll run your a/c and other inductive loads youll get some sort of current back on the ground wire (not many appliances are balanced perfectly across the hot wires), and if you mix phases up youll heat up that ground too fast.

First, the ground wire should never have any current on it. It is meant as a fault path for safety purposes.

Shoulda, coulda, woulda. Ground is tied to neutral in most cases. While you SHOULDN'T get enough leakage to cause significant heating, if you're mixing tons of high-current appliances on different buses to a single ground, the potential exists for trouble (hee hee I made a pun). Probably not an issue....probably.

In most residential applications, it is a single phase system. perhaps you meant between the 240V sides to neutral. That is, the electrical panel has two sides, each representing a side of a center tapped transformer. Each side is 120V to the center tap, which is the neutral. This is all single phase. The neutral, or center tap, is tied to ground at the electrical panel. From there on out, the ground should never have any current on it normally.

That's what he meant by power bus A and B. They're single phase, but the phases are 180 degrees out of alignment. If you have an inductive load on each, it could easily cause there to be a slight potential between their respective "neutral" lines at any given time. If you're tying these together on the massive next-to-zero-resistance copper bar at the panel, that will drop that potential to zero with minimal heating. If you're hooking up a whole bunch of much thinner-gauge wires in some other room as part of a workshop, I could see it getting a little warm. Again, I doubt it would be a problem, but it's still somethin to think about.<shrug>

 

[zig3695]

Originally posted by: Jeff7

Originally posted by: zig3695
ehh, yeah i was implying he would use the existing circuit as a 240v feed for his a/c.... i wasnt even thinking that he probably has a 120v unit. im on a lot of vicodin today sorry....

I think one 240V unit would be enough to cool my entire apartment.
I've got 1 8000BTU unit for downstairs, and a 6000 for upstairs. I'd probably have to go to 12000 to need 240V.


Hopefully you're not drugged up when you're working.

"Izzere power in thisherething? Lemme jus lick it quick..."

hahaha! keep hopin!!

ps- i had a 240v window unit that cooled my entire 1400sq two story house on most days...

 

[Paperdoc]

Hey, you've lost focus by asking the wrong question. The problem is not just that you have only one outlet box with a ground lead in it. The real problem is that you have ONE circuit into the room with a maximum capacity of 20 amps. I don't care what you hook into that outlet box, you will not change the total capacity of the circuit, because that's set by the new breaker in the panel.

Now, you could connect all sorts of things into the single 20-amp circuit to give you many grounded outlets for plugs. (Well, actually, there are code limits on how many outlets can be on one circuit.) BUT then you would have to monitor your uses and ensure that you never exceed 20 amps total at one time. In fact, the breaker will do that for you, sort of - it will pop off if you run too much load. But if you plan to use more power than that, the only solution is to add more 20-amp new circuits, starting from the panel with a new breaker and wiring. Before you have that done (I would guess you cannot do it yourself), you need competent advice on whether the panel itself, and its supply, can accomodate more 20-amp branch circuits.

By the way, a GFCI is NOT a substitute for a ground lead! A ground lead ensures that the chassis of the load device (saw, toaster, whatever) is grounded just in case a fault causes a live wire to touch it. If that happens, the presence of a ground connection ensures two things: the current flow to ground will be VERY high and it will trip the breaker; and, the chassis should remain at nearly zero volts during that brief mishap. A GFCI, on the other hand, checks the currents flowing in the supply line and ground line; if it detects that they do not match within 5 mA, it trips itself open because there is current flowing someplace it should not. This does NOT guarantee that the unexplained current is flowing to a safe place - it could be through you! But the 5mA limit is low enough that it will prevent serious injury to you.

To be honest, I am not sure whether GFCI units need to have a good ground to "refer to" for their operation. I have no doubt they are designed for installation in modern circuits that have good grounds, but I cannot say whether they work without them.