Recomended megger for 2005 NEC 550.17 test?

[tortuga]

Anyone have a preferred megger for this test?
It requires a 1 min 900V test or 1080 for 1 sec on 600V or less wiring for mfrd buildings.
It would be nice to have some USB interface to download test results.
I am looking at a Uni-trend http://www.uni-trend.com/UT513.html
259 on ebay.

Thanks

 

[hurk27]

Anyone have a preferred megger for this test?
It requires a 1 min 900V test or 1080 for 1 sec on 600V or less wiring for mfrd buildings.
It would be nice to have some USB interface to download test results.
I am looking at a Uni-trend http://www.uni-trend.com/UT513.html
259 on ebay.

Thanks

Are you in the business of manufacturing HUD trailers? this requirement is only required in the manufacturing process before it leaves the plant, which is under the HUD CFR 24 3280.800 requirements, this is never required in the field except when and if a HUD inspector requires it to be completed by the manufacture.

 

[hurk27]

By the way article 550 is for: Mobile Homes, Manufactured Homes, and Mobile Home Parks used as dwellings.

Not for manufactured buildings not for use as a dwelling.

See 545

 

[tortuga]

Thanks for the reply, I actually have 3 code enforcement cases that have been referred to me. All involve homes that were sheetrocked before an approved rough inspection one was a large non permitted remodel. These for a variety of reasons have come to the attention of the AHJ long after completion and are facing having to remove all of the sheetrock. After a hard to schedule meeting the AHJ is happy accept this test proposal (along with a short list of other things) as the rough inspection. One of the homes was completed in 1999.
I have been researching NETA and some other stuff on testing and might have a little niche in this, perhaps groundrod testing as well as others.

Oregon also has a code amendment for having knob and tube evaluated or replaced by a contractor prior to blown in insulation. I have done this a fair bit with the Ideal Suretest, testing for voltage drop, then visual inspection and load tests.
This test would be a nice addition to the report.

Not to mention motor, xformer testing and AFCI troubleshooting.

So thanks for any feedback on a meggger to buy for a 600V and less guy.

 

[hurk27]

A'hhhh

It seemed you opening post seen to be going in another direction with the reference to article 550, and a mention of manufactured buildings.

All I use in a Meggger MIT 200, it's only a 500 volt unit, and I only use it for trouble shooting, but there are many one here who are very familiar with what's out there so hopefully they will chime in.

 

[ptonsparky]

Wandering Goat Coffee!!

OT, but how do they test K&T wiring that is free air installation then put insulation around it and even consider it safe?

 

[zog]

I 2nd the MIT series, depending on what you need they will have one. Alot of LV guys seems to like the Fluke 1507.

You mentioned doing groud rod testing, you know you don't use a megger for that right?

 

[hurk27]

Wandering Goat Coffee!!

OT, but how do they test K&T wiring that is free air installation then put insulation around it and even consider it safe?

There are many times that even a megger will not show damaged conductors, I do a few lightning strikes, and it takes knowing what to look for, lightning can blow off the insulation of NM but leave the conductors untouched and unshorted still running between supports, this is specially true with those plastic stand offs we use when we have many NM's running down a stud, meggers will many times show these conductors as good, the only proper test is using a snake camera or opening up walls.

K&T running between insulators can result in the same readings, I have even seen hots touching wood, that show in the infinity range, but over time these hots can cause carbonization of the wood and cause a fire, the only true way to find this is by visual inspection, and camera snakes are the preferred method for non-destructively looking at the cables or conductors in these cases.

 

[tortuga]

All I use in a Meggger MIT 200, it's only a 500 volt unit, and I only use it for trouble shooting

OK thanks I am looking into the MIT 400 series. Looks like it has Bluetooth wireless data transfer. I would prefer USB. Looks like it can only do a 1000V test. not a 1080. Thats probably fine.
and a rugged design.

..going in another direction with the reference to article 550, and a mention of manufactured buildings.

Yeah sorry the reference to mfd buildings was sloppy, just the test is all. The test is a nice compromise because it is in a familiar book for the AHJ.

Wandering Goat Coffee!!

Well they have free wireless and the best coffee in town, free live music at night and a some nice microwbrews on tap.

OT, but how do they test K&T wiring that is free air installation then put insulation around it and even consider it safe?

Agreed. Here is a link to the Oregon's NEC amendment. Scroll down to 918-305-0180. I don't remember what type of wire that K&T rubber conductor is. I thought it was just R.I had an old 1930's book "California electrical regulations in the workplace" that had a 310.16 type table. It listed it as 80C insulation. The Oregon amendment changed that to 60C. I don't understand why it is not enforced to be on a GFCI breaker during panel change (410.18 and 406.3(D)(2) 2005 NEC) I often do this on a panel change if I see 3 prong replacements or new light fixtures in a house on K&T or ungrounded wiring.
Customers don't like the cost though.

There are many times that even a megger will not show damaged conductors..

Agreed! That is why I have not purchased one of these yet. I have done fine with the Ideal Suretest and visual inspection.

 

[tortuga]

Ampacity table for Knob and Tube

Ampacity table for Knob and Tube

Here is a ampacity table for old wiring insulation:
http://www.archive.org/stream/wiringhousesfore00schn