House wiring problem

[Steve Barker]

Two things are happening here. #1. You are using a digital meter, a no no on AC house diagnosis. #2. Your outlet is not grounded.

[Dave]

Okay, you are correct on both counts. The outlet is not grounded, and I was using my Fluke, which I trust more than the off-brand. Would an analog meter give me a different reading from hot-gnd, or neutral-gnd? Hadn't thought about it, but it probably would, wouldn't it? Have to check that out. *Thank you*

Dave

[Dave]

Wow. So, bottom line is, an analog meter is the only thing you can really trust?

[Steve Barker]

I believe there was a trick to make a digital meter NOT show phantom voltage, but i don't remember what it is. I have a $6 meter in my bag for house electrical issues. The digital is reserved for the automotive use.

[Nate Nagel]

yes, if you want to have the "best" meters, you'll have both a digital Fluke and a Simpson 260. both are appropriate for different projects, although either one will work in a pinch.

nate

[HeyBub]

A light bulb is better else you may forever have imprinted on your memory the smell of a burning resistor.

[David Nebenzahl]

On 4/4/2010 3:15 PM Steve Barker spake thus:

Simple: put a large-ish resistance (say, 50-100K ohms) across the leads to reduce the input impedance. This will shunt any phantom (induced) voltages away from the meter.

[Stormin Mormon]

Well, you must be an engineer?

[David Nebenzahl]

On 4/4/2010 5:16 PM HeyBub spake thus:

You're not going to get a burning resistor, Bub.

Do the math. Using Ohm's law, let's say we gots a 100K resistor. If the voltage is 120, the current through it is 1.2 mA, and the power being dissipated is a little more than 1/8 watt. So use a 1/4 watt resistor if you're paranoid. Maybe a 1/2 watt one for up to 240 volt measurements.

[Evan]

That is the biggest problem with engineers, they think they can "engineer" their way to solving some problem that a good technician with installation/repair experience can diagnose almost immediately...

~ Evan

[bud--]

What can you use for shaving, cleaning you clothes and sleeping in?

The secret, IMHO, is to know the limitations of what you are using.

For a meter I would use my digital Fluke (which is category-rated). If I saw odd low voltages I would check with a light bulb in a pigtail socket. Fluke has meters that can be switched between high impedance and lower impedance. You can get a good idea if a ground is good with the pigtail light bulb. I most often use a neon test light. A 3-lite tester gives some fast information. A "non-contact" voltage tester is real nice sometimes. Check what Ralph wrote. Depends on what you want to find out.

What can you use for shaving, cleaning you clothes and sleeping in? A razor, a brush and pajamas

[Gary H]

[snip]

One double breaker (although I've seen 2 singles instead. They should be next to each other) and another (single) for the blower?

[Sam E]

[snip]

It would be a good idea for meters to include such a feature. If the reading changes, you know you've got a problem.

[N8N]

yabbut, he said that if any of the breakers were on that it'd work, that can't possibly be right.

nate

[Twayne]

Hmm, let's see, who should I trust? The engineer who intuitively knows and understands what the max wattage will be and its impact on the resistor? Something he knows intuitively, BTW, and confirms almost instantly in his mind? Or, should I trust the experienced one that says to use a

47 ohm resistor but actually only THINKS that's what it was? Besides, a 47 ohm resistor won't "explode". We had to go all the way down to a 2.2 1/8 watt before it'd explode the resistor; that was one surprised tech when he turned his bench on! Wish I could remember the composition; it wasn't carbon. In many cases, such as this one, the engineer has MORE experience in the outcome due to his knowledgable experience than the "experienced" who simply depends on "it's always been that way" and has no idea whether he's approaching a cold, a hot, or a flaming resistor? They both have the experience; but only one knows for sure it's the applicable experience to that situation.

No, I'm not an inja-neer. I just understand reality.

HTH,

Twayne`

[Twayne]

And my old Simpson 260 was easier to read from a couple feet away, too. The mirror made measurement errors due to parallax almost never happen.

[Tony Hwang]

Hi, There are two types of engineers, one is hands-on type like techs in the field. One is strictly desk bound knowing only theory. There are many EEs out there who can't even replace a blown fuse on something some where. I was not one of them.

[David Nebenzahl]

On 4/5/2010 1:57 AM Evan spake thus:

I'm not an engineer. That was just an ASS-umption on the part of Stormy in one of his malformed posts.

[Dave]

yabbut, he said that if any of the breakers were on that it'd work, that can't possibly be right.

nate

Hey nate,

Hate to say it, but that is the way it is. If any of those three breakers is on, the outside compressor comes on when called upon. This is why I said that whoever wired this house had to be stupid, crazy or on drugs (maybe all three.) Please tell me why you say it can't possibly be, and help me understand this mess.

Thanks,

Dave

[N8N]

I didn't say it couldn't *be,* I just said it couldn't be *correct.* And it's not. That's why I suggested you have an electrician check it out. It sounds like maybe the equipment got inadvertantly connected to two different circuits somehow, which is a code violation, as there needs to be a single disconnect for each circuit. Otherwise if you kill the breaker marked "A/C" and don't subsequently test it, you could get a nasty surprise.

Since you apparently have a meter, I would do the following: turn off each breaker one at a time and see if there's voltage on the wire connected to the output of that breaker. If there is, you got a problem that ought to be fixed.

nate