rodent-proofing an existing electrical switchgear enclosure

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mayanees

mayanees

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Westminster, MD
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Electrical Engineer and Master Electrician
I'm involved in a project where the 15 kV service-entrance gear to a facility is mouse- and rat-infested. They've chewed the insulation on conductors, and generally left trails all over everything. The word I get from the facility owners is that there's no way to rodent-proof because of the cable entry and exits to the sheltered-aisle switchgear enclosure, but I find that hard to believe.
I would think we could seal the cable entry points with a foam that's compatible with the insulation. They're going to try sonic transmitters, but I'd really like to see the building sealed tight.
Any suggestions or comments are appreciated.
John M
 
T

T.M.Haja Sahib

Guest
What about filling the cable ducts with sand?

It will not only act as a deterrent to rodents but also prevent propagation of cable fires along the cable duct.
 
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petersonra

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Northern illinois
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engineer
Foam might work if it was deep enough.

Rodents are tough to keep out of anything. They can get thru the tiniest of holes.

Might be time to call in an exterminator to reduce the rodent population as part of the deal.
 
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petersonra

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Northern illinois
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engineer
K8MHZ said:
Sand?

I would ask if you were kidding, but I don't think you are. :slaphead:

That's wrong on so many levels.
Click to expand...

It is a pretty common solution in the 3rd world countries I have been to. Never seen it done here. A lot of times they did not even use conduit under floors. dig a trench, pour some sand in, put the wires in, fill with sand and concrete over it.
 
K8MHZ

K8MHZ

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Michigan. It's a beautiful peninsula, I've looked
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mayanees said:
I'm involved in a project where the 15 kV service-entrance gear to a facility is mouse- and rat-infested. They've chewed the insulation on conductors, and generally left trails all over everything. The word I get from the facility owners is that there's no way to rodent-proof because of the cable entry and exits to the sheltered-aisle switchgear enclosure, but I find that hard to believe.
I would think we could seal the cable entry points with a foam that's compatible with the insulation. They're going to try sonic transmitters, but I'd really like to see the building sealed tight.
Any suggestions or comments are appreciated.
John M
Click to expand...

The only effective enclosures I have seen are MESA cabinets, and even then on rare occasion a mouse would still get in. MESA, or Manufactured Environmentally Sealed Architecture, not only seals all holes in the cabinet, but uses a fan to keep positive pressure in the cabinet.

I have read mixed reviews about sonic transmitters. I think some lab proved they didn't work.

If 'Great Stuff' is compatible with the insulation, I seriously doubt a critter could chew through a couple inches of it, but you never know. I have seen them chew through an inch of wood.

I have never seen a rodent chew through plumber's putty (duct seal). I'm not saying they won't, I'm just saying that in all my years, I have never seen it.
 
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T.M.Haja Sahib

Guest
KBMHZ:
You did not mention any effectiveness of sand filling cable ducts to keep out rodents.
 
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ritelec

ritelec

Senior Member
Location
Jersey
petersonra said:
It is a pretty common solution in the 3rd world countries I have been to. Never seen it done here. A lot of times they did not even use conduit under floors. dig a trench, pour some sand in, put the wires in, fill with sand and concrete over it.
Click to expand...

So the way things are going, soon we too may be able to deploy these methods?
 
zog

zog

Senior Member
Location
Charlotte, NC
You could keep a cat in there (Warning, graphic)

(MODERATOR'S NOTE: We do not allow such graphics. I deleted it.)
 
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mayanees

mayanees

Senior Member
Location
Westminster, MD
Occupation
Electrical Engineer and Master Electrician
.. thanks

.. thanks

K8MHZ, thanks for the product referral. It looks appropriate.
ZOG!!! Good God man!!! It's lunchtime!!! .. and the warning did nothing but encourage viewing!
John M
 
Jraef

Jraef

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Location
San Francisco Bay Area, CA, USA
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I did a bunch of low-head hydro generator systems in Idaho one year at the end of the '70s, by the end of the summer we were 100% on our ratio of installations with rattlesnakes inside. The first one was such a shocker that to this day I think of that every time I open an electrical cabinet.
 
rbalex

rbalex

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Location
Mission Viejo, CA
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Professional Electrical Engineer
It's common enough to use a fine "pea gravel" in refineries to fill a manhole, handhole or other significant depression in a Classified location. The filled depression is then considered to be below-grade and "unclassified" under NFPA 497 or API-RP500. This may not work in some Article 510-516 applications but it is "suitable"[500.8(A)(3)] for most general Article 500/501 applications.

"Standard" sand will effectively become "sandstone" quickly with enough water cycles. The key is getting fairly smooth surfaced granular material that can be vacuumed out if necessary. Conceptually its like 314.29 Exception only the depression is filled rather than simply covered.

I don't have a photo readily available, but I'll try to post one later.
 
RichB

RichB

Senior Member
Location
Tacoma, Wa
Occupation
Electrician/Electrical Inspector
We just started using a product called Todol Duo-fill 400 It's supposed to be rodent and insect resistant. It's a foam sealant BTW
 
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