Another Megohmmeter Thread

[ivsenroute]

I first used "meggers", the crank type when I worked on electrical systems of aircraft in the Marine Corps back in the 80's and have not used one since.

I spent many years in doing industrial electrical maintenance, installation and troubleshooting but never had a megger at my disposal and it did not appear to affect our jobs.

I see a lot of talk about megohmmeters and I have read and searched many threads on this forum that have great information.

My questions are:

What is your number one reason for using one (specific function)?

Would there be any reason for a residential electrician to have one?

 

[brian john]

What is your number one reason for using one (specific function)?

To verify before energizing that the distribution equipment is safe to energize.

To track insulation deterioration over a period of time.

To verify the insulation values after a flood, blow up or other possible contamination.

To check the resistance to ground of the neutral grounded system downstream from the main neutral ground bond.

Would there be any reason for a residential electrician to have one?

For the reasons noted above.
Lightning strikes

 

[480sparky]

For the reasons noted above.
Lightning strikes

Add to that....

HOs
DIYs.

 

[celtic]

add to that...careless installers.

 

[480sparky]

add to that...careless installers.

And the fact the wiring has been around for more than a century. You'll undoubtedly come across wiring that's 50+years old.

 

[ivsenroute]

I heard some good things about the Fluke 1507

 

[mdshunk]

I heard some good things about the Fluke 1507

The actual equipment you'd select would depend in large part on what sort of electrical work you typically do.

 

[ivsenroute]

I have been thinking about a megohmmeter (just thinking) because when I do residential I see a lot of older homes that still have K&T and other older types of cable with deteriorated insulation.

I have already had 2 lightning strike jobs this year and I could only repair the affected systems.

It would be a bonus in the commercial and industrial area if I have an opportunity for service work. My industrial experience is in motor controls, PLC's including programming, automated controls and my specialty is troubleshooting which I have a knack for .

 

[ivsenroute]

bumpity bump bump

 

[cadpoint]

Go buy yourself one, they'll make more...

Tell the Bride its a tool that will pay for itself, or say other (excuse) ...

 

[boboelectric]

I like to apply an amprobe 500 volt megger to any circuits in doudt.It checks circuits under over voltage conditions.

 

[Chamuit]

Would the Ideal 61-795 be okeedokee one?

I'm in the same situation as ivensroute except we have been doing more commercial work this year. Would "look good" and trully be good to do this as a regular practice.

 

[ivsenroute]

Although I have not used a megohmmeter in a while, I have only used the crack style and don't know how good these new-fangled ones are.

 

[brian john]

For the most part all the meggers from major manufactures I have used are decent. It really depends on what you are doing with the instrument (crank, battery, line connected, multiple test voltages, resolution ECT), this will drive the cost up.

 

[SEO]

For the most part all the meggers from major manufactures I have used are decent. It really depends on what you are doing with the instrument (crank, battery, line connected, multiple test voltages, resolution ECT), this will drive the cost up.

Brian have you ever heard of somebody destroying equipment with a megger at 1000v or less?

 

[mdshunk]

Brian have you ever heard of somebody destroying equipment with a megger at 1000v or less?

I certainly have. Cordless phones, board in a furnace, defrost control in a heat pump, garage door opener.... and the list goes on.

 

[iwire]

Collateral damages Marc?:grin:

 

[ivsenroute]

I can certainly see in any application of the megohmmeter where it would be labor intensive to test circuits by having to de-energize the circuit and removing anything that is plugged in, probably including removing light bulbs and leaving the light switch in the on position in order to test as far as possible down the circuit.

For commercial with a lighting problem this could take some time. I assume that all ballasts would have to be disconnected from the circuit.

 

[mdshunk]

Collateral damages Marc?:grin:

I just call it tuition. Education is expensive.

 

[mdshunk]

I can certainly see in any application of the megohmmeter where it would be labor intensive to test circuits by having to de-energize the circuit and removing anything that is plugged in, probably including removing light bulbs and leaving the light switch in the on position in order to test as far as possible down the circuit.

For commercial with a lighting problem this could take some time. I assume that all ballasts would have to be disconnected from the circuit.

You don't have to do any of that if you're only testing line to ground. When you're hunting a fault, most of the time that's the sort of fault you're hunting.