230V 'polarity'?

snip

Tell me about it! A freind called for some help. She had a LICENSED electrican working on the entry/stairs/hall/LR light switch panel on a

1920 house. He had taken all the switches out, had all the wires hanging out, could NOT get it back together again, walked out! I taped a 24"x36" sheet of paper over the box and started tracing wires. 2 hours later I discoverd that the box had 3 DIFFERENT wiring systems in it! 1) curent code with NM and hot/neutral/ground 2) knob and tube with switched hot and 3) knob and tube with switched wherever (on the neutral in this case) All of this was legal since it was grandfathered in.

I'd sure like a copy of the book but $75 for a used copy seems pretty steep. Is it really THAT good? I do have his smaller book on reserve.

Reply to
RoyJ
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I do have a mentor help with the wiring, I have been so far doing everything to code, I believe the only flaw to fix here is to open my heater and breaker and label that white wire I used. I used a dual pole breaker (bracket that ties the 2 levels together) for my last

220V installation, conduit, etc was all done.

My original question was really meant to ask more whether swapping the

2 hots would make a motor spin backwards, now I know it does not matter. I did mention white and black wire for the heater I might have misread the colors in the manual; it might have called for black and another color instead of white.

As for the wire gauge, the heater installation called for 10 Awg and

30 amp breaker, (though running at 5000W 20.3 amps @ 240V), wire was slightly under 25 ft. The compressor also calls for 30 amp breaker minimum, as far as I know it is a 5HP motor. According to this chart sounds like 10Awg handles 25 or 30 amps? so I might step up to 8 Awg. The run will be 40 ft.

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As far as potentially hurting others, these are direct wire installations, no one is likely going to tap into the circuit, and the circuit is likely to be removed completely if I move. Yes, I am not experienced, but I do try to consult and do things to code.

Reply to
jeremy_ho

Unless you put a "trip tie" on the breakers to tie them together. But it IS better to use a 2 pole breaker. (which is just 2 breakers in one case)

Reply to
clare at snyder.on.ca

It WOULD be done with a 3 wire cable - most definitely. And if YOU are doing it, it only makes sense to use 3 wire. You NEVER know what you may want to connect to that plug in the future. A welder may well have a 110 volt fan, or a 110 volt wire feed unit. It may use 110 to provide low voltage for remote controls. You may want to use some other 220 volt device that has 110 volt lighting in it, all kinds of possibilities. You MIGHT even want to use that plug with a circuit splitter to run two 110 volt devices off a 220 volt extention cord.

You can never go wrong using the proper 3 wire cable, even if the code MIGHT allow you to scrimp and use 2 wire for a particular application.

Reply to
clare at snyder.on.ca

Or just get 2-wire cable with black and red colour coding (instead of black and white). No need to insulate the ground.

Dave

Reply to
Dave Martindale

There is black/red Romex with bare ground. I've used it. It's appropriate anywhere you're supplying a pure 240 V load (e.g. baseboard heater, electric water heater). Taping the white wire in black/white NM cable is basically simulating a cable with non-white insulation on that conductor.

Dave

Reply to
Dave Martindale

Well not exactly the same. A two (or 3 or even the rare 4) pole breaker will (Usually) have a single trip latch mechanism. THis is more reliable than a handle tie, which relies on the spring of one breaker to overcenter the trip on the other pole or poles.

jk

Reply to
jk

Nothing wrong with knob & tube, and in some respects it is better than NM cable.

I had this in my previous house, not just switched whatever, but reversed whatever to the sockets. Found this the hard way when I connected to computers on opposite sides of the room to each other with a serial cable. WHen the smoke cleared, there was a hole on my PC board where a chip used to be.

jk

Reply to
jk

I helped my grandpa rewire a house that was knob and tube. His power use was always too high. At some point, someone had used a gas pipe for a ground (it had gas lighting) and used a hot wire.

Grandpa found that out one day when he cut into a gas line he was removing and bridged a waterpipe. Big flash, damaged hacksaw blade.

As far as the electrician that walked out it was a very unprofesional response.

Wes S

Reply to
clutch

I don't know what else is in your garage, but running a subpanel might be a good idea rather than just a 60 amp circuit. A subpanel would include a neutral and a ground. If it is just a 60 amp circuit to a purely 220V device, there would be no neutral needed. You can get non-metallic insulated cable assemblies in the range of wire sizes you are considering and beyond. Next time you're at Home Depot, take a look at the wall of wire rolls.

Reply to
ATP*

I got both his books from the library. If your local one doesn't have them you might try interlibrary loan. They are not books I feel I would need to own, but are most definately worth reading once.

His other book, 'Your Old Wiring' is more aimed at the complete novice, and he wrote 'this is beyond the scope of this book' a bit too often for me personally, but to be fair he is putting safety as his number one priority and is trying to avoid all assumptions about the reader's level of knowledge.

The "Maintenance And Retrofit" book has some very intriguing references at the back, but you might need a good reference library to find them.

He also has a fair bit of wiring History sprinkled about, some of which is non-technical but entertaining. I found it particularly amusing to learn that when Con-Ed switched over to AC in Manhatten, they did the switchover working their way from the South end to the North. They offered free AC appliances to the customers who made the switch, trading back the old DC appliances. These they refurbished and sold cheaply to the customers in the North end who still had DC. Sometimes the same applicance was sold multiple times....

Mickey

Reply to
Mickey Feldman

Snip!

If you think about it, since AC 'goes' first one way, then the other, if the rotational direction of the motor depended on which of the external wires were connected to the main input wires, then the direction the motor rotated would depend on exactly where in the cycle the power was at the moment you hit the switch. Half the time (on average) it would be clockwise, the other half counter clockwise. (Or maybe the poor motor would just sit there humming to itself and not move... I do that sometimes myself.)

There are quite a few different designs of AC motors, but all of thm have some means of creating an offset between the magnetic field of the rotating part, and the magnetic field of the stationary part. In the cases where the end user can alter this, there are usually internal terminals in the motor to allow you to switch certain windings in or out of the circuit, or to change the phase relationship of one winding relative to another. Any relatively new motor you find will have a connection diagram on the name plate if it is reversable in this way. (There are other designs, such as 'repulsion-induction' which are reversed differently, but you're less likely to encounter them.) Since it costs more to include this feature, motors which are designed for a specific application which does not require them to be reversed are not likely to actually be reversable. This probably includes your compressor motor.

Glad to hear you're working to code. Strickly speaking 'to code' means 'with a permit and inspection'. I've never heard of trouble with an insurance company due to omitting this little detail, but I did worry about it once...!

Mickey

Reply to
Mickey Feldman

Sigh..according to code..as William says..black is hot..white is neutral.

In the REAL WORLD © however...half the US is wired with black and white wires IE 220.

No self respecting electrician or guy with more experience beyond putting a new plug on the end of a lamp cord is going NOT check to see what the voltage is and on such a compressor..will..will...will assume that the white also is hot before determining for himself its not a

110vt circuits, and then wired correctly.

I work in industrial invironments everyday..and find that even three phase circuits are going to be all color of the rainbow..and half of them are going to be wired with a chunk of 3 wire extension cord..the green one being used as the third leg of a 3ph circuit. 4 wire SOW is much more money..so...sigh.

So its unlikely you are going to kill anyone (unless they are due to be a Darwin event anyways) and a shit load of such is out there.

If Im forced to use 2 wire romex..I simply wrap the white wire with black tape back to the jacket on BOTH ends. Same with using an odd color for ground..I keep a couple rolls of Green electrical tape in the tool pouch for this reason.

Code says it has to be plainly marked on both ends..and colored tape will be acceptible in most areas. Not all..but most.

Same with 3ph wiring, which tends to be black/white/red here in So Cal in most shops. Though I perfer black/blue/red for such..shrug.

Gunner

Political Correctness

A doctrine fostered by a delusional, illogical liberal minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.

Reply to
Gunner

Not in So. Cal. It may be solid to the disconnect..but is generally stranded to the compressor. The fatigue thing.

And most guys prefer stranded simply because it pulls better

Gunner

Political Correctness

A doctrine fostered by a delusional, illogical liberal minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.

Reply to
Gunner

You would be surprised how often that happens. You often end up with a big knot in there, and it can be confusing even if you are the one who wired it in the first place.

Old houses, old rules.

There were 3-way switch circuits developed in the WW-II era when copper was rationed - Coast Traveler and Carter System. Basically, they switched power and neutral to each side of the lamp, which allowed them to use one less wire. Put hot on both sides of a lamp and it will not light - but you'll get a hell of a surprise if you think it's dead and try working on it...

And then there are the color goofs - up until the 1950's, Green was used as a power conductor, there was no such thing as safety ground wires. Homeowner remodels the house and then they can't get the power back on, breaker trips on a hard short. Open up boxes till you find where they dutifully bonded the green wire they found to the box.

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Reply to
Bruce L. Bergman

Stranded is preferred anywhere you are going to get motion and high vibration - and especially for large motors #8 wire and above (they make it up to 500MCM) you use special "motor lead wire" that is fine stranded, rather than the coarse strands you get in large sizes of normal "stranded" wire. For motor duty even 14 & 12 stranded building wire isn't /that/ flexible, but it's a lot better than solid.

Stranded may pull better for long runs, but it's a pain in the keister to terminate it in switches and receptacles, you have to use lugs everywhere. And it costs more than solid. You use solid out to the disconnect switch, and stranded where you need it.

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Reply to
Bruce L. Bergman

Yes. The cheesy little side tabs they give you on some screw posts that are rated for stranded terminations are really inadequate.

Reply to
ATP*

Crimp terminals are not very hard to use...

i
Reply to
Ignoramus18738

The operation takes a lot longer on a commercial job. But my point was that UL's requirements for stranded terminations seem inadequate in some cases. I think you should have a full cup washer or the type of termination that presses a plate against the wire if you use stranded without crimp terminals.

Reply to
ATP*

You are right. For my own noncommercial wiring, I am a big fan, nowadays, of crimp terminals and stranded wire.

i
Reply to
Ignoramus18738

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