Inspection of Conduit Seal Pour

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SEO

Senior Member
Location
Michigan
I like to look in the sealoff prior to the fill to make sure that the damming compound is seperating the conductors then after the fill before the hole plug is tightened in make another inspection of the actual fill.
 

Natfuelbilll

Senior Member
Could a test or inspection be performed with a pressure gauge and schraeder valve/handpump that was threaded into the plug opening?

If so, what amount of pressure would prove the seal?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Look at FPN #1 to 501.15.
... Even at differences in pressure across the seal equivalent to a few inches of water, there may be a slow passage of gas or vapor through a seal and through conductors passing through the seal ...
 

KentAT

Senior Member
Location
Northeastern PA
Hi Guys

Any good techniques to verify conduit seals have been properlypoured after the job was done?

You can't come after the fact and verify that the seals were properly poured as far as all the requirements are concerned, without destruction of the seal. The only way to know for sure is to be present when the seals are poured.

For a properly poured seal, how would you check the following:

(1) separation of conductors - in a conduit run, you can't check this.
(2) proper mixing of seal compound per the mfg instructions - how will you know?
(3) proper fiber damming - how can you be sure that the area to contain the compound doesn't contain fiber also?
(4) proper application temperature of ambient for compound curing - how do you know?
(5) proper use of the compound specified by the seal mfg. - I know realistically it shouldn't matter, but if the mfg. specifies to use their compound, you gotta do it
(6) proper thickness of seal compound - can be done if you have a plug to remove that lets you see the thickness that is required (trade size of seal, and no less than 5/8")

Point is, to inspect a seal for proper installation, seals need to be inspected immediately prior to the pour for correct preparation and during the pour for correct use of the compound.

I don't see any other way.

Kent
 
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rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
All good points; I'd like to comment on item (5).

Item 5: The reason it matters is that the seal fitting hasn’t been tested with the “foreign” compounds. Both the NEC and UL specifically require the seal and compound to be compatible.

NEC:
501.15 (C) (1) Fittings …Sealing fittings shall be listed for use with one or more specific compounds and shall be accessible.
UL 2008 “White Book”:

CONDUIT FITTINGS FOR USE IN HAZARDOUS LOCATIONS (EBNV)
GENERAL

Conduit fittings for sealing are intended for use only with sealing compounds specified by the manufacturer in instructions furnished with the fitting.
Your point is well taken that other sealing compounds may work, but the NEC and UL want it to be a tested combination.
 

masterinbama

Senior Member
At a liquid hydrogen facility I worked on years ago ,they actually had a guy that would follow you around as you were poring your seals. He had done so many of them I actually learned some really neat tricks from him.
 

nakulak

Senior Member
At a liquid hydrogen facility I worked on years ago ,they actually had a guy that would follow you around as you were poring your seals. He had done so many of them I actually learned some really neat tricks from him.

how about listing some of these neat tricks ?
 

masterinbama

Senior Member
One trick is to roll your packing wool into little balls. Then you use those to seperate your conductors. Then add another layer of wool on top of that. The other one was to use distilled water for the chico. He said something about the chlorine in the water made the compound coagulate instead of mixing cleanly.
 

nakulak

Senior Member
distilled water, interesting. How about the actual pouring - have any neat trick for that. Other problem/pia I have is packing the verticals - any tricks for that ?
 

hardworkingstiff

Senior Member
Location
Wilmington, NC
how about listing some of these neat tricks ?

One thing I learned (thought it was neat) was to take a 16-20 oz soda bottle (or water, etc) and the spout from a 1-quart container of wire lube. Mix the sealing compound, then (after cleaning out the old product) pour it into the bottle, the spout from the lube container will screw onto the bottle and you can pour the sealoffs so much easier and with better control than pouring from the mixing cup.
 

Natfuelbilll

Senior Member
A mineral insulated cable manufacturer suggests in their literature that some companies x-ray conduit seal for inspection.

Ever heard of that before?
 

jmargolis79

Member
Location
minneapolis
I roll my fiber into little snakes. you can then push the snakes around the wires and into the back of the seal. I use a small dixie cup and mark a line on it in order in insure the proper mixing ratio. I found a basic funnel with a 18 inch hose on the end. The hose on the end make it easy to pour th seal even if it's close to something. As long as you rinse out the funnel before the compound dries it works great.

What tools do you use to pack the fiber? I have tried many things,the back side of a pencil works ok. I know their are tools made for this but our shop hasn't wanted to purchase any.
 

kameele

Member
Location
NH
A filling method that I can't take any credit for (I'm stealing it from an old electrician) is to use one of the keg-shaped mustard bottles. You can easily measure in the compound and water, put the cover on to shake, and the pointy nozzle makes it very easy to inject the right amount into the seal.
 
A filling method that I can't take any credit for (I'm stealing it from an old electrician) is to use one of the keg-shaped mustard bottles. You can easily measure in the compound and water, put the cover on to shake, and the pointy nozzle makes it very easy to inject the right amount into the seal.

Does it make the same sound as with mustard?:D

You may want to warn people around before use........
 

Rockyd

Senior Member
Location
Nevada
Occupation
Retired after 40 years as an electrician.
If you have a lot of seals to do, chop sticks, and various pieces of plastic that you can reshape with a heat gun to fit behind conductors, and follow shape of pipe will help a lot.

Whatever you do, don't use anything metal to pack chico with!
 
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