Megger hazards

[Mike Williams]

If you are testing conductors with a megger and someone down stream touches the wire you are testing can they receive a lethal shock?

 

[charlie b]

I believe so, but I am not certain. The megger supplies over 500 volts, and that is enough to give a fatal shock. What I do not know is the internal impedance of the megger. The test is looking for very small amounts of leakage current. The internal impedance of the device might be high enough to prevent the current from reaching a harmful level. Someone else will have to take it from here.

 

[zog]

Charlie is right, voltage is high enough but smaller hand held meggers wont produce enough current for lethal shock, but may cause you to fall off a ladder or something. I have been meggered dozens of times, scares you more than anything. Some larger 5kV and 10kV megger may do some damage, as will hipots, but usually they have safety features built in for protection.

 

[nakulak]

yes, large meggers (thumpers) can kill you. On one of his videos, Mr. Holt relayed a specific case of an instructor who was giving a training class using a thumper and killed himself in front of the class (the insulation on the leads was bad and the shock killed him)

 

[rocha1]

Does anyone know the typical output of a 5k megger

 

[zog]

5,000V/(Rload+Rmeter)

 

[rocha1]

I has kind of hoping for the current output, the original question was never answered. Can a megger produce a lethal shock?

 

[mdshunk]

I has kind of hoping for the current output, the original question was never answered. Can a megger produce a lethal shock?

The question was answered, and the basic answer is yes. What is unclear, however, is what model or type is being asked about in particular.

 

[rocha1]

I'm having a hard time with that answer without some justification. I don't believe a megger can produce enough current to injure a healthy individual.
Lets limit the discussion to 5Kv and below.

 

[nakulak]

you don't have to believe it - contact a few manufacturer's or download the instructions and see what they say.
(what exactly is a healthy individual anyway ? some people go thru their whole life with heart irregularities etc that they never even know they have)

here's a link for you to peruse (scroll down):
http://www.ccohs.ca/newsletters/hsreport/issues/2006/03/ezine.html

 

[rocha1]

I have, they all say "Danger of electric shock" not lethal shock. Unless someone is turning the crank the only output is capacitance, with no current increase potential

 

[mdshunk]

I'm having a hard time with that answer without some justification. I don't believe a megger can produce enough current to injure a healthy individual.
Lets limit the discussion to 5Kv and below.

Okay, fine, but you just arbitrarily picked that out of the sky. The basic tool that we call a "megger" for slang comes in many sizes. When they get larger, we often quit calling them a megger and have other pet names for them.

 

[480sparky]

I have, they all say "Danger of electric shock" not lethal shock. Unless someone is turning the crank the only output is capacitance, with no current increase potential

True story: Years ago, I wired a cardiologist's office. In the treadmill room was a defibrillator. On that difibrillator was a warning sticker: "Caution: Risk of Electric Shock!"

 

[zog]

Okay, fine, but you just arbitrarily picked that out of the sky. The basic tool that we call a "megger" for slang comes in many sizes. When they get larger, we often quit calling them a megger and have other pet names for them.

Actually Megger is a brand name, used commonly like kleenex is. A Megohmeter has an output voltage from 250V up to 10kV depending on the model. All Megohmeters are DC. It is used to measure resistance values of insulation up to TOhms. Think of it as a ohmeter on steroids.

Then there are dielectric test sets, commonly refered to as Hipots, they can be DC or AC (60hZ or VLF) and is used to measure leakage currents, available with outputs up to 100kV (Highest I have used anyways)

A thumper is a different device than either, no measuring of anything, just used to find the weak point in insulation and (for lack of a better term) blow it out.

Then there are specialty types of overpotential test sets, Tan Delta, Pf, etc, lets not get into those, but closer to a hipot than anything else listed here.

I have been meggered many times, and will be again, not that big of a deal but if the stars are all aligned (Worse case conditions) I believe they could possibly deliver a fatal shock, but most likely not, internal meter resistance is just too high.

hipots and thumpers, are very dangerous, been hipotted once and never want to again, thumpers will kill you.

 

[zog]

I has kind of hoping for the current output, the original question was never answered. Can a megger produce a lethal shock?

I answered your question as clear as it can be answered

I=5,000V/(Rload+Rmeter)

 

[76nemo]

The question was answered, and the basic answer is yes. What is unclear, however, is what model or type is being asked about in particular.

I am stumped on this one. I use the Fluke 1520 and 1507. I mainly work alone. Are you telling me megging branches even with 500V can have a lethal jolt for someone on down the line in a straight feed

 

[76nemo]

I am stumped on this one. I use the Fluke 1520 and 1507. I mainly work alone. Are you telling me megging branches even with 500V can have a lethal jolt for someone on down the line in a straight feed

I am not looking for thee answer of,.."Not someone with a bad heart."

 

[nakulak]

 

[76nemo]

I don't mean a thumper, they are not user friendly:grin:

 

[mdshunk]

I am stumped on this one. I use the Fluke 1520 and 1507. I mainly work alone. Are you telling me megging branches even with 500V can have a lethal jolt for someone on down the line in a straight feed

I really have no idea, but I'd have to assume that it should be respected. At least, injuries resulting from a megger can be secondary to the shock, such as raising up quickly and bumping your head, or falling off a ladder. Let me shock 1,000 people with a megger a few times, and I'm pretty sure I can kill a couple of them.