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#47392 01/14/05 08:39 PM
Joined: Aug 2001
Posts: 151
Dallas Offline OP
Since hiring in with this company, one of my "fill-in" projects is to install Type 2 TVSS on incoming utility power (and generator output) at a customer's sites. TVSS ans customer's specs call for the TVSS to be installed either at building disconnect or site transfer switch. The TVSS is usually 120/240 1ph, and calls for a #10 wire, although my predecessors have been using #6. My problem is HOW to connect the TVSS to the lugs on the disconnects or xfr switches. Most of these sites are 200A services, the disconnects are standard ones, with the incoming lugs almost surrounded by formed plastic/insulative materials, and rated at accepting a 350 or 500 kcmil wire. The generator lugs are just as large.

My problem is landing the TVSS conductors alongside with the installed conductors. right now, the SOP is to just back off the lugs and install the TVSS wires "on top of" the existing ones. I sure as heck don't like doing that, and one of the reasons for them hiring me was to minimize non-NEC installs just like this one. But so far, I have yet to come up with a satisfactory method of installing the wires, that meets all the other criteria I have to meet. Costs, mostly.

I can't replace the lugs with doubles, (won't fit without major reconstruction changing original construction), and although I've drilled and tapped small holes for control wire lugs, a lug the size necessary for a #10 or #6 is too large for a tapped hole in a manufacturer's installed lug (in my opinion).

Any suggestions? I'm really frustrated doing this jackleg style, but I can't find a better answer yet. There's just over 400 of these TVSS installed, or on Work Order to be installed, and they're a contract price, so nothing major can be changed.

Also, the sites are VERY dependent on power, with limited battery back-up time, so complete shut down is out of the question for anything longer than a short time.

#47393 01/14/05 10:18 PM
Joined: Nov 2000
Posts: 246
I seem to remember some double-lugs that have a cylinder base, to fit into a standard lug, thus allowing you to terminate 2 wires.

What about adding a non-thermal breaker to feed the TVSS. Most TVSS manufacturers have some fusing installed, and allow this type of connection.

As a last resort, what about installing a compression type of splice onto the existing wire, kind of like the type some utilities use to connect service conductors. Of course, these will need to have either a cover installed, or may need to be taped up.

Installing 2 wires in a lug rated for only 1 is a code violtation, and should not be done.

Rick Miell

#47394 01/15/05 12:00 AM
Joined: Nov 2000
Posts: 2,148
285.21 requires the TVSS connection on the load side of the service or building disconnect unless it is also listed as a surge arrester in compliance with Article 280.

#47395 01/15/05 12:50 AM
Joined: Aug 2001
Posts: 151
Dallas Offline OP

The fact that these are non-compliant installs are what's eating at me. But until I have something economically viable (and commercially available) to take to the powers-that-be, I'm caught in the "it's working fine, just do it" management brush-off routine.

I've thought about using a "c-tap" crimp for adding the TVSS conductors, but I've had to install this newer TVSS to replace older, less optioned ones, and replace the wiring, so something reversible would be best, since I'm sure this will repeat itself as an upgraded version with options the engineers like becomes available.
I kinda remember those lugs as well, but all my available suppliers are drawing a blank on them. I'm afraid they're no longer made. Any one have a source for them? THOSE would be my best option, and should be OK to Mgmt and the client engineers, too.

These are rated surge arrestors/suppressors that are dual rated for Type 1 or Type 2 installs. Customer specs want them installed as Type 2, as the building is remote from the service, and they're WAY more concerned with protecting what's in the building than the SE wires from the meter/main disc. So, they're mounted at the building disconnect, OR, more often at the xfr sw terminals inside(usually) the buildings. But I'll note the NEC ref, and keep it for future arguments. Thanks.

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