Random Question?

dkillianjr

Hey guys, heres another random question I have been meaning to ask for a while. It could be a dumb one But why is it that illuminated switches don't need a neutral? Is it cause essentially its wired in series?



Dave

InPhase277

Most, yes. Depends on the type of switch. If it is light on/switch illuminated, it needs a neutral. If it is light off/switch illuminated, it doesn't need a neutral. When this type is off, the neon bulb is in series with the load. Not enough current flow to light the load, but enough for the switch.

InPhase277

randomkiller

Actually, it's because when the switch is open there is potential across it's contacts and that is where the bulb is in the circuit. Just like reading fuses with a voltmeter, if your probes are on a blown one you'll read voltage across it.

__________________
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InPhase277

Only an idiot would check a fuse in-circuit

InPhase277

mdshunk

Maybe, maybe not. Don't do it with a Wiggy, or it'll blow up in your hands. With a DMM, no problem.

dkillianjr

Thanks guys, I knew it was something along those lines. Its just like testing christmas light bulbs


Dave

Ponsse

What are you talking about? I check fuses all the time with a wiggy. They're rated 600 Volts RMS, 1000 volts peak. You leave the disconnect on, override the lock on the door with your screwdriver (that's why the slot is there) and test each fuse just like randomkiller suggested. Every maintenance electrician I've ever worked with checks this way otherwise you would have to remove every fuse in the bucket and test, and nobody has ever been "blown up"!

mdshunk

Okay dokey. Keep thinking that way. Doesn't matter to me.

How many amps will that solenoid coil handle? How many amps will those leads handle? You do realize that if you check across a 200 amp fuse, there's 200 amps flowing literally through your Wiggy, don't you?

Ponsse

It has nothing to do with the size of the fuse, It's the resistance of the coil!!!!!!!!!!!

Ponsse

Seriously, what part of this don't you understand?

Royal-T

This is off topic, but I dont care because I am not an electrician. I need a sparky, and we are in the same area. Send me a pm with the info on how to get in touch with you. I have a job for you. This would be the one I mentioned the other day about the metal device, metal box with newspaper stuffed in it for a draft blocker!

mdshunk

I understand it quite well. If, for instance, you have a big heating element on the load side of that blown fuse, and you check across it with a solenoid type tester, you will have current flow through that Wiggy to fire up those elements for the period of time you have that meter around that fuse. Same thing on control circuits. You can actually jump out a limit or interlock for the period of time you're testing around it with a Wiggy. This is Wiggy 101 stuff here, and is important for you to know.

mdshunk

I replied to you before, and I told you that you're too far away from me. Almost every job I ever do is within 10 minutes of each other. You're hours away from me. No thanks.

Royal-T

I never got the response, my electrician flaked out on me and I need a new one in the Harrisburg area. If you have anyone you would suggest around here, let me know, I need a good one. Thanks alot!!

Royal-T

By the way, "Give'em Hell" Sometimes these kids know everything. "If you know everything, you will learn nothing"

macmikeman

A 200 amp fuse with its load side conductor connected to a motor makes for an even splashier display when a wiggy is connected across the blown fuse. If your feeling brave, you should try that one sometime.

Ponsse

The current flow through the coil is negligable on your point on resistive circuits, just as the current flow through your DMM is negligable, yes you have a current flow through your fluke. Yes your right, I can pull in a control circuit with my wiggy, it has enough current for that but sometimes this is what you want. There are 1000 different ways to troubleshoot a circuit. If I'm testing, I know what I'm testing for, and when and where to use my wiggy. I can spend all week trying to teach you when, where, and how to use a wiggy, but I don't have the time or patience ----- so back to your initial statements.

Your point about blowing up a wiggy across a 200 amp fuse is completely wrong. It doesn't matter if I'm across a 5 amp fuse, a 200 amp fuse or directly across 2 phases at 575 volts, the current flow is only changed by the voltage. The resistance, or on an AC circuit, the impedance is fixed in the coil.
I have seen a wiggy "blow up" as I'm sure you haven't by your foolish statements. It was "blown up" along with a starter by testing across two phases of a 2300 volt starter. After the arc was started it sustained itself until the conductors were completely vaporized, it was 20 years ago but I believe they were around 500 MCM conductors. The electrician was shaken but is still working in the same plant.
In this case your DMM would have "blown up" too. You need to learn some DMM 101 basics if you think there's something special about your meter before you kill yourself.

Do you understand yet the concept behind testing across fuses and not having 200 amps flowing through a wiggy?

cmec

IN SERIES with the fuse holder unless your wiggy had a dead short in it hows it gonna carry 200 amps?

To check for an open phase,or blown fuse ,Why would you test across a fuse holder in series anyway,

OR load side to neutral?

Shouldnt you pull readings in parellel across the line side and load side of the fuseholder for voltage ?

Ponsse

It won't pull 200 amps or blow up, that's the point I'm trying to get across to Shunk.

macmikeman

Oh? then in that case if you substitute a 15 amp fuse in the block for the 200 amp fuse somehow, it won't blow under load either, cause its limited by the impedence of the 15 amp fuselink. Not.