Is this permissable?

[kentirwin]

I have a situation where I work (industrial) where we are going to install TVSS's on two Square D QED 4000A service swithcboards. The vendor informed my supervisor that the devices need to be as close as possible to the feed breaker with minimal wire bending. Unfortunately I was not present for this discussion. The vendor went on to state that it was okay to mount the TVSS right on the face of the removable panels on the FRONT of the switchgear as long as we used an approved chase nipple or whatever. I have not yet contacted Square D, but right off the top of my head this doesn't sound like something they would sign off on, not to mention code issues with access, etc. So what do you guys think? :roll:

 

[iwire]

Re: Is this permissable?

I think it is a lousy idea and if the TVSS is deeper than 6" a violation of 110.26(A)(3)

 

[milwaukeesteve]

Re: Is this permissable?

I don't see how this works myself.
If you have a TVSS for a 4000A service, that unit will be quite large and heavy, physically. That is something that probably would require mounting beyond a simple chase nipple, and would be too heavy to mount to a removable cover.
If the cover was a hinged cover, I may be able to see that, but I don't know.
In regards to working clearance, same thing with the hinged cover. If it is mounted to the hinged cover, then working clearances are not hindered since you are able to open the door.

Also with clearances, you are still working with unit equipment. Same thing as if you had a 6" deep panel between 2 8" panels. All of the panels are unit equipment and do not hinder the others area.

 

[kentirwin]

Re: Is this permissable?

The vertical wireway covers are the ones being referred to. They are not hinged, just fastened with screws. They are the covers you remove to terminate, determinate, install a breaker, remove a breaker, use a meter, etc. I have a call into the local Square D field office now. I'm almost certain what they're going to tell me - HELL NO! The TVSS weighs 30lbs., is 7"D X 9 3/8W X 10 3/4H. My intention, since sometimes what many people say carries alot more weight than what one person says, is to email this thread.

 

[jim dungar]

Re: Is this permissable?

TVSS are not sized based on amps, so one for a 4000A service could be the same size as one for a 400A service. Typically the most important TVSS factor is the fault handling ability.

The ability to clear faults is dependent on the impedance of the conductors connecting the TVSS to the power system and to ground. So the vendor was correct in that you want these leads as short as possible (mounting on the gear is preferable to mounting on a distant wall). The vendor is probably not an expert on compliance with the NEC, in fact most manufacturers literature always has the caveat "must be installed per NEC and any applicable local codes". this is why many swichgear manufacturer make TVSS units that connect just like branch feeders.

You need to review the lead size/length resistrictions in the installation instructions.
I have seen many installations of equipment mounted to the sides or even on top of switchgear.

 

[kentirwin]

Re: Is this permissable?

We are indeed able to mount the TVSS's on top of both gears. That's not a problem. That's what I want to do. Because of arrangement of existing breakers and more importantly length of existing conductors, we'll have to feed them out of the bottom pole spaces. So wire length (60A ckt) will be 6 - 7'. BTW, since my last post my local Square D engineer called me. While we would have to go to all the way to the factory to get an "official" ruling, he agrees with me that we would probably not receive the factory's blessing, NEC issues aside.

 

[don_resqcapt19]

Re: Is this permissable?

It is my understanding that if you have 6 or 7' of conductor to the TVSS you might as well not even put them in. There is a marked decrease in effectiveness with conductor lengths over 6 or 8".
Don

 

[jim dungar]

Re: Is this permissable?

If you have the room, splice and move your existing conductors/breakers. Be sure you know the exact lead length restrictions, as Don said for residential type devices length is measured in inches.

If there is room in your switchboard, have you looked at their plug-on TVSS choices?

 

[marinesgt0411]

Re: Is this permissable?

in the past we have mounted the tvss on top of the switch gear,next to the switch gear,or on the access panel of the switch gear. and have not had a problem with the AHJ or square-D the access panel you mount to is the one that needs to be removed to pull the wires a few quarter 20's and fender washers. nuts to the outside bolts to the inside to keep them from coming loose inside switchgear (bolt, fender washer, access panel,fender washer,nut, tvss,nut) cuts down on length of conductors and moves tvss closer to breakers. just a suggestion do not take it as gospel

 

[kentirwin]

Re: Is this permissable?

Thanks for the replies. I was not aware of the degree of criticality with conductor length. We'll be forced to splice existing conductors in order to rearrange existing breakers so as to get the TVSS OCPD's as close as possible to the top of the switchboards. When I get back to work tomorrow I'll revisit using the top (not a wireway) access panels for mounting vs. the top of the gear itself. Thanks again.

 

[kentirwin]

Re: Is this permissable?

Update time... We have received the TVSS devices that started this thread and I just opened one up. The "guts" of the unit are epoxy (or something like it) encased and fill the entire back of the can - not removable. This means I can't really mount on the face of anything. Recall the vendor recommended mounting on the face of a wireway on our QED switchboard! Whatever - this means it gets mounted on the top of the gear and that lengthens the conductors. These are "Innovative Technology" units. Has anyone had any experience with this particular brand? :roll:

 

[steve66]

Re: Is this permissable?

I went to a half-day seminar on those units. If you can believe the sales rep, they are pretty good.

If I remember right, they bragged that the epoxy disipated heat faster and increased the life of the MOV's.

Steve

 

[physis]

Re: Is this permissable?

I've never used these TVSS things, at least not under that acronymn.

What are they made of?

Besides epoxy.

 

[69boss302]

Re: Is this permissable?

I have a question, these wouldn't happen to be a unit called stedi volt would they?

Those were put in by my predecessor, whom no longer works here, HMMMMM amazing how the timing worked out. I have had many calls saying that we as a company had been used as a reference for this product. I have denied any association with it and as a matter of fact so has my boss and all up the management ladder. I do not like these things and the way the salesman paints the picture. If they did what they say, we could put them all over the place and sell power back to the POCO.

 

[steve66]

Re: Is this permissable?

No, a quick internet search shows stedi-volt is a different company.

It looks like Innovative technology has been bought by Eaton. I think that gives them some creditibility.

innovative technology

Steve

 

[hurk27]

Re: Is this permissable?

I went to there site and I could not find any that were just epoxy and the one designed to be for load end had this

*Recognized components under UL 1449 Second Edition & UL 1283

Which means the whole device was not ul listed H'mmmm?

 

[69boss302]

Re: Is this permissable?

Originally posted by steve66:
Eaton. I think that gives them some creditability.

Personally I wouldn't give the word EATON all that much credibility. Where I used to work they were actually one of our customers, their business ethics and products can use a bit more scrutinizing just as much as the rest.

Edit: Spelling of course, actually what is it write spelling of same word but means something different when you spell it another way. Our English language is even amazing and we wonder why it is so hard to understand the code.

[ July 13, 2005, 06:42 AM: Message edited by: 69boss302 ]

 

[kentirwin]

Re: Is this permissable?

I just looked at the specs for the units. They claim UL1449 listed, second edition and UL1283 filter. We have two types - PTX300 for two 4000A QED switchboards and PTX160 for two I-Line distribution panels. After looking in one of the switchgears yesterday and some digital photos of a newly installed 1600A distribution panel, I hit on the bright idea of mounting the units INTERNAL to the panels/switchgears. In the switchgears we can actually mount the units to the concrete slab and wire to an adjacent breaker with shortest possible length of conductor and fewest bends. In at least the new 1600A panel we can either floor mount it or mount it on the backpanel. I have no documentation that lists them for internal mounting. However, there is PLENTY of clearance from live parts. Nobody but qualified personnel will ever go in there. My boss says go for it. What say ye??