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Old 05-31-2013, 03:27 PM   #1
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old rusted out burried EMT? advice appreciated.




this is the conduit that services an outdoor remote elec. recepticals in the back corner of my back yard as well as the 500w light for an in ground pool. i was planning on moving said outlet about 10 feet onto a post that im building to hold something like a 150w MH or maby some flouro flood lights.

i was surprised to find that the conduit was EMT? isnt PVC far cheaper than even the super thin EMT? the pool was put in in the 80's from what i understand, i just dont understand why EMT was used. anyway as you can see its rusted heavily, and id like to know what i can do about this? i really dont want to do all the work of installing this post with a new light and remote hose faucet only to have the emt fail and the wiring short out.
its worth noting that the area that this rusted EMT lies in is the lowest part of the yard. im in houston and the soil here is very poor draining, i happen to know this area of the yard takes almost a week to dry out completely after a good rain storm. ive actually taken to spraying Malathion in this area when i can to keep the mosquitos down. so im assuming i need some caulk or electrical duct putty to keep the moisture out?

the big problem is that most... about 80% of this emt is under the pool deck, so i cant just trench it all out and replace it. since im already trenching about 80 feet for a 3/4" buried pvc line to serve the hose faucet, im thinking i will just run pvc conduit next to it with a strong piece of nylon cord inside it?

my thinking is that when the EMT fails ill just use the nylon cord to pull through a new set of stranded THHN wires? or should i maby just bury some special direct burial cable? if so then which is cheaper?

i went out and bought a PVC valve box to hold a buried junction box,
http://www.homedepot.com/p/Orbit-7-i...9#.UakG05yOAi0

i also bought some PVC conduit, however i decided to not just jump into this one without looking... i thought it best to pick the brains of some of the professionals here before burying anything.

id really appreciate any advice you guys can give me, thanks!

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Old 05-31-2013, 03:46 PM   #2
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old rusted out burried EMT? advice appreciated.


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Originally Posted by Queequeg152 View Post
...about 80% of this emt is under the pool deck
You'll need to RE-FEED the circuit in a new trench.
All new conduit, wire, boxes... the works.

The existing conduit & wire can either be dug up
and disposed of or abandoned in place.

google Ditch Witch
picture LINK

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Old 05-31-2013, 03:49 PM   #3
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old rusted out burried EMT? advice appreciated.


It's not unusual to find EMT used in an older home. As you found it doesn't last forever. PVC was just starting to come into favor back then.

As to your pool, there are codes that apply to wiring near pools. Depending upon how close you are to the pool you may need to use conduit and not direct burial cable. Check with an electrician or your local AHJ as to what code cycle you are on and if there are any amendments.
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Old 05-31-2013, 04:52 PM   #4
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old rusted out burried EMT? advice appreciated.


Quote:
Originally Posted by TarheelTerp View Post
You'll need to RE-FEED the circuit in a new trench.
All new conduit, wire, boxes... the works.

The existing conduit & wire can either be dug up
and disposed of or abandoned in place.

google Ditch Witch
picture LINK
thanks for the advice, i don't think ill need a ditch witch, the trench is already dug for the plumbing i mentioned. i assume its alright to put the conduit in the same trench as the plumbing?

also it should be noted that the section of metallic conduit servicing the pool light dives down about 5' into the earth( the section of conduit on the left), and is covered by slab about 6" thick. i am not going to replace this conduit untill it becomes necessary. what i had planned initially is to place the burried valve box over the section of conduit, cut them both, re wire the pool light to the new junction box and some how re ground to the existing non-removable conduit section with one of those clamp on lugs and a length of THNN. ill have to use the angle grinder w/ wire wheel to get a good surface to ground to i imagine.

does that sound acceptable to you? TBH im not even averse to abandoning the pool light all together. its not terribly useful, as its placement poorly lights the shallow end of this L shaped pool

to clarify, you think it is a bad idea to essentially wait for it to fail and then replace it with the already in place section of burried EMT w/ pulling rope i mentioned above?
Do you mind if i ask you why? i imagine its a decent safety issue, but wont the breaker just trip when it shorts to ground?

Quote:
Originally Posted by AandPDan View Post
It's not unusual to find EMT used in an older home. As you found it doesn't last forever. PVC was just starting to come into favor back then.

As to your pool, there are codes that apply to wiring near pools. Depending upon how close you are to the pool you may need to use conduit and not direct burial cable. Check with an electrician or your local AHJ as to what code cycle you are on and if there are any amendments.
we are on 2008 now, from what i remember anything close to the pool needs to be bonded to the pool bonding grid. i hadn't given this much thought as it will be grounded through the panel which is obviously grounded to the rod.
I'm pretty sure the pool is bonded to the panel....besides the underwater light, the pool pumps are the only things bonded to the shell i think... i know the pumps are tied to the grounding rod with a brass fitting. i assume this is to give any current in the water a path to a safe ground? or perhaps this is to just ground the pump casings...

this section of the NEC always confused me, and honestly deterred me from installing some outdoor ceiling fans years ago. someone told me they added this to the nec mostly to address things like metallic ladders and lighting that can conduct stray current in soil into the water?
Do you have any info you could toss at me regarding this topic? id really appreciate it. thanks!

Last edited by Queequeg152; 05-31-2013 at 04:59 PM.
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Old 05-31-2013, 06:27 PM   #5
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old rusted out burried EMT? advice appreciated.


There is a lot of information that we don't have about your pool to provide specifics. Check out this link, it should help answer a lot of your questions as it discusses conduit, grounding, bonding, everything. Chapter 680 is where you need to be.

http://www.mikeholt.com/files/PDF/Pooldownload.pdf

It has pictures!
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Old 06-03-2013, 12:19 PM   #6
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old rusted out burried EMT? advice appreciated.


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Originally Posted by AandPDan View Post
There is a lot of information that we don't have about your pool to provide specifics. Check out this link, it should help answer a lot of your questions as it discusses conduit, grounding, bonding, everything. Chapter 680 is where you need to be.

http://www.mikeholt.com/files/PDF/Pooldownload.pdf

It has pictures!

wow so Mr. Mike Holt sure knows how to break it down for the dummies like myself.

i was not aware of alot of what is mentioned therein. ill have to get a gfci breaker for the pool light circuit i guess, was not aware of that one.

my pools very old so im fairly sure it does not have a true equipotential bonding grid. just a lug fitting onto the rebar, held together with steel wire wrap that's tightened with regular lineman pliers.

FWIW, i dont think it was mentioned in your link but here the city now requires a ring of 8 gauge copper around the perimeter of the shell at the top for most in ground pools. if you have a pool deck, it will be bonded to this ring along with any lights and ladders etc. ive seen a few comments from city planners( i used to do cad work with several pool contractors), and they all seem to want that wire ring
my pool will not have any of this, its too old.

the conduit is definatly greater than 5' from the shell( the shell is like 6' all around) , the post will be 10', so no problems there, but what do you think i should do with the light?

like i said i was just going to cut the emt, put an elbow on it and bring it higher up out of the wet ground, then fasten a grounding lug to it. do you think i should just abandon it instead? its defiantly not feasible to saw cut and excavate to the shell.

any comment on weather i can just lay the conduit with a pulling rope now, then wait for it to fail? sounds haphazard, but it defiantly works as it is, feels strange to fix what is not broken.
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Old 06-03-2013, 06:11 PM   #7
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old rusted out burried EMT? advice appreciated.


Are you sure it's EMT? It should be rigid conduit, GRC.

You could always put in the PVC and a pull for the future.
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Old 06-03-2013, 06:22 PM   #8
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old rusted out burried EMT? advice appreciated.


Quote:
Originally Posted by Queequeg152 View Post
my pools very old so im fairly sure it does not have..
here the city now requires...
my pool will not have any of this
What you have now should NOT be energized.

If/when you start repairing what you have you open yourself up to doing that work by current code and very likely bringing large parts of the area otherwise up to current code.

Quote:
i was just going to cut the emt, put an elbow on it and bring it higher up out of the wet ground... do you think i should just abandon it instead?
See post #2
Ditch Witch and all new.
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Old 06-04-2013, 12:41 PM   #9
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old rusted out burried EMT? advice appreciated.


Quote:
Originally Posted by AandPDan View Post
Are you sure it's EMT? It should be rigid conduit, GRC.

You could always put in the PVC and a pull for the future.
Sorry, as a layman i just call any metallic conduit EMT. i do understand there are significant differences. GRC has the threaded couplings correct? it is not easy to bend correct? FWIW, i know this stuff IS bent, you can see a 45 barely in the pic above.
however i should note that i have not seen any of the unions as of yet

Quote:
Originally Posted by TarheelTerp View Post
What you have now should NOT be energized.

If/when you start repairing what you have you open yourself up to doing that work by current code and very likely bringing large parts of the area otherwise up to current code.

See post #2
Ditch Witch and all new.
ill look into that, but i dont believe what im doing constitutes a "substantial improvement", as it does not approach even a small amount of the homes appraised value.

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