"live" work; How often?? - Page 5 - Electrician Talk - Professional Electrical Contractors Forum

Raco · 09-28-2009, 06:46 PM

Quote:

Originally Posted by sparks134

if i put in jumpers at the meter, then I guess I would tie in the neutral first then the hots!

I would shut off the main and remove any jumpers before splicing. Why would you chance the arc?

nitro71 · 10-06-2009, 02:12 PM

Get yourself a Fluke tick tester and use it on everything once the service has been energized. The biggest lie you are going to hear is that power is off and it's safe for you to work on. Test everything.

JohnJ0906 · 10-06-2009, 07:50 PM

Quote:

Originally Posted by nitro71

Get yourself a Fluke tick tester and use it on everything once the service has been energized. The biggest lie you are going to hear is that power is off and it's safe for you to work on. Test everything.

I agree with the testing, but use a real tester, such as a DMM, don't use a tick stick.

Briancraig81 · 10-14-2009, 02:18 AM

Quote:

I think a blast from a receptacle on a circuit with a high amperage load on it might be worse than clean 120.

I once shorted out a hot meter (Briefly) once. We were working on an old house way out in the sticks, house had one of those small round meter bases (60a). Meter wasn't in (House had just been bought) and we had both legs jumped with two pieces of #12 just so we could run the sawzall and rotary hammer. Got ready to leave and instead of pulling the line side of the jumper out first I grabbed the jumper right in the middle and tried to pull it out at once. Load side pulled loose and touched the side of the meter base. I got a nice bright flash and a loud pop but that was all. I was jerking the jumper out, so it shorted and then pulled out on the line side. Other than being blind for a few seconds, I was fine.

Puccagirl · 10-14-2009, 11:30 PM

When I was a an apprentice a ga-zillion years ago, we had little choice but to work on live ccts (347 volt lighting) in places like stairwells or where emergency lighting could not be shut off.

I was scared of being shocked so I was very careful. Although I did short 600volts once.. (only once) but wasn't very eventful other than shutting off some lights in an elevator.

I know of an electrical engineer who opened up some old switchgear and something blew up. He was in the hospital and in treatment for a year getting skin graphs.. very scary and makes you develop a respect for electricity.

RH1 · 10-15-2009, 10:21 PM

Quote:

Originally Posted by Zog

Actually it is the opposite, higher voltages cause a "skin effect", so the current tracks on the surface of the skin and will not penatrate the skin and cause burning of the nervous systems and blood vessels. (Same reason hollow tubes are used for HV outdoor substations, no need for the center to exist)

Lower voltages puncture the skin and cause current to flow thorugh the circulatory and nervous systems causing internal burns and nerve damages.

Of course voltage is only 1 of 8 factors that determine the severity of an elcetric shock, but discounting all other factors, lower voltages are more dangerous than higher voltages simply due to the skin effect.

It's clear you haven't a clue what skin effect is. Skin effect has nothing to do with voltage, it is a function of frequency and it only happens at frequencies above VHF.
.
.

Zog · 10-16-2009, 10:01 AM

Quote:

Originally Posted by RH1

It's clear you haven't a clue what skin effect is. Skin effect has nothing to do with voltage, it is a function of frequency and it only happens at frequencies above VHF.
.
.

There is a different type of skin effect, which is present at all frequencies in an AC system, this is refering to the increase in conductor effective resistance from the eddy currents developed in AC systems, these eddy currents (More apparant in the center of the conductor) are directly related to frequency so the effective resistance of a conductor will increase as frequency increases.

Skin effect from high voltages is a different concept and is accounted for in the design of every high voltage system

Toronto Sparky · 10-21-2009, 01:00 AM

Quote:

Originally Posted by Raco

What's the fault current on that outlet which is on a 15 or 20 amp breaker?

What's the fault current on your drop which is fused somewhere down the line at what current? Linemen want to step in?

100,000 amps or more?

Voltage isn't what kills us.. it's the amps and the flashes they produce.
Very few electricians get electrocuted, most get burned!