IOR requesting LB to be sealed

[oldnomad]

During an inspection this morning the IOR requested an LB to be sealed with a sealant. He stated when a raceway enters a building from the exterior, the interior of the raceway is to be sealed. He referred to 225.27 It's my understanding that the LB has a gasket and is weather tight and this would meet the code. Has anyone come across this?

 

[wwhitney]

The LB gasket protects against water entering the LB through the body/cover joint. But what 225.27 calls for is the use of Duct Seal or equivalent inside the conduit to fill the void space between the wires and the conduit walls.

That prevents air from moving through the conduit between inside and outside. Which air movement, in addition to being an undesirable air leak in the building envelope, could allow condensation inside the conduit. E.g. in a climate where the outside dewpoint can exceed the interior temperature, or vice versa.

Cheers, Wayne

 

[oldnomad]

The LB gasket protects against water entering the LB through the body/cover joint. But what 225.27 calls for is the use of Duct Seal or equivalent inside the conduit to fill the void space between the wires and the conduit walls.

That prevents air from moving through the conduit between inside and outside. Which air movement, in addition to being an undesirable air leak in the building envelope, could allow condensation inside the conduit. E.g. in a climate where the outside dewpoint can exceed the interior temperature, or vice versa.

Cheers, Wayne

Thank you

 

[infinity]

There are several sealing requirements in the NEC. There is the one you've mentioned in Artciel 225, there is one in Article 230 for services fed from underground and another in 300.7 for raceways run in areas subject to different temperatures.

 

[xformer]

The LB gasket protects against water entering the LB through the body/cover joint. But what 225.27 calls for is the use of Duct Seal or equivalent inside the conduit to fill the void space between the wires and the conduit walls.

That prevents air from moving through the conduit between inside and outside. Which air movement, in addition to being an undesirable air leak in the building envelope, could allow condensation inside the conduit. E.g. in a climate where the outside dewpoint can exceed the interior temperature, or vice versa.

Cheers, Wayne

Also to keep potentially toxic or hazardous gas from entering the structure.

 

[infinity]

Also to keep potentially toxic or hazardous gas from entering the structure.

Is that actually in the NEC? I wouldn't think that duct seal would do a good job at keeping either of those from entering.

 

[xformer]

Is that actually in the NEC? I wouldn't think that duct seal would do a good job at keeping either of those from entering.

300.5 G Info note

 

[tom baker]

It’s the interior of a raceway into a box, or lb that is to be sealed. Pack some duct seal inside the LB.

 

[norcal]

The IOR inspecting for OSHPOD?

 

[grich]

Also to keep potentially toxic or hazardous gas from entering the structure.

And wasps. Ask me how I know.

 

[xformer]

And wasps. Ask me how I know.

ok... How do you know?

 

[grich]

ok... How do you know?

When I opened my panel at home and found it full of wasps! The seal on the weatherhead was compromised and the darn things came all the way down through the meter can and inside. I had a brick of duct seal on hand, and made quick work of that. The weatherhead was replaced later, along with the bent mast caused by a careless contractor.

 

[xformer]

When I opened my panel at home and found it full of wasps! The seal on the weatherhead was compromised and the darn things came all the way down through the meter can and inside. I had a brick of duct seal on hand, and made quick work of that. The weatherhead was replaced later, along with the bent mast caused by a careless contractor.

is wasp spray electrically conductive?

 

[hillbilly1]

 

[kwired]

During an inspection this morning the IOR requested an LB to be sealed with a sealant. He stated when a raceway enters a building from the exterior, the interior of the raceway is to be sealed. He referred to 225.27 It's my understanding that the LB has a gasket and is weather tight and this would meet the code. Has anyone come across this?

The LB gasket protects against water entering the LB through the body/cover joint. But what 225.27 calls for is the use of Duct Seal or equivalent inside the conduit to fill the void space between the wires and the conduit walls.

That prevents air from moving through the conduit between inside and outside. Which air movement, in addition to being an undesirable air leak in the building envelope, could allow condensation inside the conduit. E.g. in a climate where the outside dewpoint can exceed the interior temperature, or vice versa.

Cheers, Wayne

wwhitney covered the main reason why - condensation when there is differences in air temperature on each side. This is mentioned in a few other places and not just applicable to art 225. It pretty much is the rule anytime there is temperature difference on each end of a raceway. I don't think you specifically need to place sealant in the conduit body in question though, any place that will prevent air flow between the two temperatures will get the job done. I often will do it at an LB that is entering the building, but sometimes is more practical to do it at either of the two ends of the run. The LB already has a gasket and kind of is no different than not having it there from perspective of air flowing through it.

 

[grich]

is wasp spray electrically conductive?

There are a lot of water-based sprays now. You have to read the label...the non-conductive sprays make it obvious...usually rated to 35kV.

 

[kwired]

There are a lot of water-based sprays now. You have to read the label...the non-conductive sprays make it obvious...usually rated to 35kV.

I would guess oil based sprays are naturally less conductive, but that is just my guess. Probably more effective at instant knock down of the wasps as well, but more likely to stain or leave residue on surfaces.

When I was a kid, on my grandparents farm the go to method was putting a little diesel fuel in a hand held tank sprayer.

 

[grich]

I keep seeing these British murder-mystery shows, set in the 1920's through the 50's, where it seems every manor house has cyanide in the gardener's shed to mix up into wasp spray. Inevitably, some of it gets diverted into someone's tea...