Basic Test Leads

[briansalomon]

I am wondering what is being used at the higher end labs for basic, everyday test leads for calibrating 4 1/2 digit DMMs.

I've been using Pomona for years but the quality has deteriorated and I don't see anything out there that is an industrial build, high quality product.

They obviously need to be rated at 1000 Volts and 20 Amps. I personally like Beryllium Copper but need durability and quality.

What do you use?

[Squidley]

The NASA JSC lab used Pomona gold plate banana leads for general meter cal. And for the high accuracy meters they used the fluke leads... Or that's what was used up to the end of January when I was laid off...

[briansalomon]

I've decided to just keep buying the Pomona gold plated 15A leads.

I have Pomona P/N 2948-36-2 (red) and -0 (blk)      They aren't going to last but will work and they're stackable.

It's a shame they laid you off. Personally, it I had my druthers I'd be working with nothing but ex-military.

[Hawaii596]

We have a little bit of everything.  For 8-1/2 digit, and sometimes 6-1/2 digit, we use the Fluke 5440-7002 series (even got a part number to replace worn banana springs on them from Fluke).

We use regular pomonas on everything 4-1/2 and down.  We have some of the pomona double banana shielded twin lead (some with guard, some without). 

We also have bunches of gold spade lug pomonas. 

And we have some high end, high current, shielded coax Pomona brand (I think) gold plated spade leads with one thick spade lug on the main lead, and a shielded guard lead.  Very nice for certain applications.

I keep a spool of AWG12 and another spool of AWG14 solid copper (from Home Depot electrician section) to use with some high current applications.

I also have some home made leads using RG-59B/U solid copper center conductor.  I trim back the shield, leaving some dielectric (white or clear) and the plain copper lead.  I connect the copper braided shield as guard.  I use them for some of my high accuracy low resistance measurements (not shunt type, but 1, 10, 100 Ohms or so).

We also have a spool of Belden twin lead, and another spool of solid copper shielded twin lead that we use to make some custom leads when needed.

That's about it for DC/AC Volts and Current and resistance. 

[briansalomon]

I'd like the P/N for the 5440A-7002 spring replacement part.

[Hawaii596]

Looks like the part number is FLUKE P/N: 1963214, and the price was $3.10 each as of December 2015.

NOTE:  when removing or replacing, use a jewelers screwdriver to "GENTLY" pry apart the top of the spring during removal.  As you remove the spring, if you are not careful about this, the sharp top edge of the spring will shear the edges of the plastic at the tip of the connector.

Also, before replacing, I take a little Caig Deoxit D100L and clean the oxides off the copper shaft (while the spring has been removed).

Then, during installation of the new spring, "GENTLY" pry open just the smallest amount to avoid damagind the plastic at the tip (just don't pry enough to permanently bend the spring).

The easy way to tell if a spring needs replacing is if you insert into a Fluke deepwell connector and it keeps popping out, it's time to replace the spring.  Once replaced, it is like night and day.

I love these leads, but those banana springs - the way those springs wear out - not so much.

Hope this helps.

ADDED NOTE:  This is an unpublished part number.  One of my techs got with Fluke on the phone and they gave it to him.  So it is not a secret part number.  Just an FYI on how we got the P/N.

[briansalomon]

Thanks. You anticipated my next question about how they are replaced.

[Hawaii596]

Glad to hopefully be of help.  We have about a dozen or more total lead sets (bot the long and short length versions.  And with the exception of the wearing out of those banana springs, those leads are absolutely THE best I know of.  The only other little feature I kind of don't care for is the spring loaded hoods.  Been trying to think of a professional looking way to disable them, as they also contribute to the leads popping out.  I also regularly remind the techs not to leave them connected to instruments, as that also contributes to the permanent compressing of the springs.

The other little thing we just also started doing, was put a P-Touch on each lead set with the date we last changed the springs.  Makes it a little more convenient when feeling "ambitious", not to double replace on ones you already recently did.

[Awesome14]

You wouldn't ordinarily think of this, since silicone insulation is overkill for test leads, but I assemble my own leads from pro-audio banana plugs and 10 AWG stranded silicone-insulated wire. Their quite flexible and nice to work with, and low resistance (1mOhm/foot).

I use Nakamichi 24K gold plated bananas from Amazon.com. I know people have different suppliers, the reference is just to get a look at them. Thermal emf is well-controlled.

This type of lead is indispensable for measuring extremely low internal resistance, such as the 10V output of the Fluke 732B.

I solder the terminals also.