# Duct seal on terminations



## Lone Crapshooter (Nov 8, 2008)

Why did the old timers use duct seal on the low voltage large wire terminations.I see this a lot where I work in a industrial setting of the 40's and 50's era . It is generally duct seal on the lug then friction tape and Glyptal .
Thanks

LC


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## CADPoint (Jul 5, 2007)

That's for the anti-bug highway.


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## Southeast Power (Jan 18, 2009)

Lone Crapshooter said:


> Why did the old timers use duct seal on the low voltage large wire terminations.I see this a lot where I work in a industrial setting of the 40's and 50's era . It is generally duct seal on the lug then friction tape and Glyptal .
> Thanks
> 
> LC


Glyptal. That's a word I have not heard in a very long time. 

I've seen bugs like that but not lugs.


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## chicken steve (Mar 22, 2011)

It seals out air, so less corrosion. 

The _'bomb proof'_ method required a lot of ado.....

_brushing of conductors

no lox them

install split bolt conn

dip in scotchcoat & let dry

cover with dux seal

then add tape_

nobody is going to take the time with so many_ 'quicky'_ products marketed these days

~CS~


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## Southeast Power (Jan 18, 2009)

Did I tell you guys about the time I found the can of SCOTCHKOTE on its side in my truck?
The smell lets you know what kind of day you are going to have.


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## Big John (May 23, 2010)

Lone Crapshooter said:


> Why did the old timers use duct seal on the low voltage large wire terminations....


 It creates a nice, smooth surface that reduces the likelihood of the hardware wearing through the insulation, without having to do a huge tape buildup. 

On MV terminations it also acts as a poor-man's semiconductor and can be used to easily fill voids where partial discharge might otherwise occur.

I hate the stuff, especially when used in MV, because that means it was applied directly to the metal and now all be conductive surfaces must be cleaned free of gum in order to remake the connection. Takes forever.


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## varmit (Apr 19, 2009)

The tape, in common use back then, usually friction tape, was not very stretchy, so the duct seal served to smooth out the connection hardware to where the slice could be taped effectively.

These splices are a challenge to clean for reconnections, especially if the splice has been hot enough to "melt" the duct seal.


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## JW Splicer (Mar 15, 2014)

We still use a lot of varnished cambric, friction, and duct deal.


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## Big John (May 23, 2010)

JW Splicer said:


> We still use a lot of varnished cambric, friction, and duct deal.


 Well, now at least I have someone to blame....


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## varmit (Apr 19, 2009)

I still use friction for "punch through resistance". Back wrap 33. 2 or 3 passes of friction. Cap with 33.


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## Lone Crapshooter (Nov 8, 2008)

Thanks for everyone's reply. I also ask a electrician that had worked allot in the steel mills and he also told me that it was used to make taping easier.

Thanks again LC


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## Jlarson (Jun 28, 2009)

More tape voodoo.


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## glen1971 (Oct 10, 2012)

I've done a couple of MV installs that it was in their spec to use duct seal on the bus connections... It's a huge PITA if they do wire inspections afterwards and have to megger or hipot...


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## Lone Crapshooter (Nov 8, 2008)

I have been doing industrial electrical work sense 83 and I have never seen a new install using duct seal it has always been on 40's and 50's installs. 
Now we use Raychem heat shrink on the 15 KV and a slip on boot on the SWGR tab that is supplied by the gear manufacturer. 
2400 is not insulated unless the spacing is close or it is in a transformer that is outside . 480 is uninsulated . When we feel it is necessary we use 15KV heat shrink tape . It is good for everything.

LC


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