Reply posted by Jay Paul on April 14, 2000

I suggest that you avoid the 66 block and use the ADC split cylinder instead. You can either buy it as an ADC product or buy it from Whirlwind, packaged as a Mass Punch Block. Whirlwind offers the ADC pin, on a smaller form factor chassis. Given that you have a 24-in square box, you may not need the space, then again having extra for service loop isn't a bad idea.

Alternatively, if you choose to go with a screw terminal block, have a look at Entrelec. They produce a terminal block for 22-ga wire, that mounts on DIN rail. Really does lend itself to your intended use.

Finally, if you haven't done so already, you should confirm that your attic is not an air plenum. If it is, don't run standard PVC snake cable through, unless it is conduit.

It seems to me that using the euro-block would prevent us from having to buy (and keep) a special punch-down tool, even though it would take slightly longer. My concern is that we do this thing correctly so that it continues to work reliably after 10 or 20 years.

Jay Paul


Reply posted by David Foulke on April 14, 2000

Thanks for the input. Everyone has given me great ideas. I am, however, curious as to why you recommend avoiding the 66 block connector? From what I've read, the 66 blocks provide a reliable gas-tight connection (with the proper $100 tool) and I can get them at my local electrical supply house.

Also, the four columns seem to lend themselves to incoming from mic -- split to MON -- FOH -- unused. The only drawback is that there are 50 rows instead of 48 or 51 (I guess the Telco people never considered we'd want to use these for connecting shielded twisted pairs). The bottom line is this: I have zippo experience with either of these and whatever termination we use, we are unlikely to reconfigure it more than once every couple of years! Therefore, I want to get it right the first time and I'm very interested in the advantage of the ADC-type split cylinder (also gas tight) over the 66 Block.

BTW, the attack space is truly that. It contains a wooden catwalk that we use change light bulbs in the high (35') ceiling and lower the chandeliers down via a winch. It is not plenum space so we don't need to use CMP cable or conduit. Hanging the snake to the bottom support joist of the catwalk seems so much easier than running 200+ feet of conduit for discrete cables and the snake is quite well protected.

For that matter, we could run a bunch of discrete cables this way -- but bulk snake doesn't seem that much more expensive and it sure is convenient having it all bundled up in one jacket. Am I making a mistake in doing this?


Reply posted by Rusty Buckner on April 19, 2000

You can execute some truly elegant solutions to the termination problem with the Whirlwind stuff. It is pricey, though. Still, you're only going to be doing it once (or so). You could even use the old solder-type "Christmas tree" terminals given that it's not going to change that often. What you save in purchase costs (with the solder type terminals) are generally more than offset with the increased labor costs, though.

It's my impression (perhaps mistaken) that the 66-type block was designed to work with solid wire, not stranded. This can have some effect on reliability. I have seen studios where the techs have gone back and soldered the wires to the terminals in an attempt to resolve glitchey problems. I have also seen installations where the wires were tinned before being punched down into the block, which would seem to negate the advantage of using a punch-down type of terminal. Still, lots of them have been used in lots of installations, so they must not be all bad. If I had my druthers, though, I'd go with the ADC/Whirlwind type of termination.

Discrete runs of shielded pair (Belden 8451, for example) will give you somewhat better performance, particularly in the area of crosstalk and capacitance. And, IMHO, discrete cables are somewhat easier (and require no special techniques) to terminate with connectors. Still, standard mic snake cable will give plenty adequate performance in this application. Ya pays your money and ya makes your choices. If you are going to use a punch down type of termination, I highly recommend using a cable with at least 22 ga. internal wires.

Good luck with it.

Rusty


Reply posted by tboles on April 28, 2000

Strain relief the line pair, before you punch it down!! The Telco 66 are fine for perm install.
Key to hi-rel with any type of IDC (Insulation displacement connector) is NO wire movement after punch down.

66 blocks are cheap and good for ONE HIT only. Try not to pull a miss connection and repunch...

T b.


Reply posted by Jay Paul on April 20, 2000

The issue of stranded conductors is two fold, the 66 block will cut some strands off, and because the post isn't shielded you are exposed to potential shorts.

One of the biggest advantages is that when you punch down on the ADC block you will *know* that you have made a solid connection. If someone mucks up a pin, you can replace it. I'm not sure that you can do that withe 66 block. The ADC block will accept 4 conductors per pin, two on each side of the block. I've loaded ADC blocks up when bringing multiple sub stage panels into a main snake, and paralleling with a master input panel.

It is not plenum space, so we don't need to use CMP cable or conduit. Hanging the snake to the bottom support joist of the catwalk seems so much easier than running 200+ feet of conduit for discrete cables and the snake is quite well protected. For that matter, we could run a bunch of discrete cables this way -- but bulk snake doesn't seem that much more expensive and it sure is convenient having it all bundled up in one jacket. Am I making a mistake in doing this?

No, I don't see a problem with that approach.

Good luck with your project!