EMT Conduit outdoors

[automaton]

I have two questions about using conduit outside. I see ALOT of installations in the neighborhood (old homes) where an electrician has run EMT outside. It was my understanding that one needed to use Rigid. I need to run a security light on exterior wall and would like to avoid using PVC (dogs can damage it).

Question 1: Is EMT permitted on the outside of wall exposed to elements utilizing proper seal tight connections and sealent?

Question 2: What are the proper grounding procedures for this?

 

[petersonra]

Re: EMT Conduit outdoors

Are the fittings and boxes being used rain tight? If so, it is acceptable.

Think about it. It would make no sense to have rain tight fittings available for EMT if you could only install them where there is no rain.

see 358.10(C)

<added>
Bonding of EMT in outdoor areas is the same as indoor areas.

[ August 10, 2005, 07:08 PM: Message edited by: petersonra ]

 

[charlie]

Re: EMT Conduit outdoors

Bonding of EMT in outdoor areas is the same as indoor areas.

In my opinion, even though it is not normally required by the NEC, I would install a grounding conductor to insure that all the equipment is indeed bonded. Of course this statement would not apply to service entrance.

 

[automaton]

Re: EMT Conduit outdoors

I 100% agree about the fittings, thats why I worded it like that in my question. I thought that this was acceptable, I just wanted to confirm it with you guys. Indeed I plan to ground as if it were indoors, I just wasnt sure if there were any other measures necessary when conduit is going to be directly exposed to natural elements. I plan to run a NM cable from panel to conduit leading to a 90 or elbow, then 10' up to a round box external mounted with water tight seal. I figure I will have to add a ground to properly ground the conduit and box. I am really tired right now, so I am not sure if I explained that well. Does this sound acceptable?

 

[petersonra]

Re: EMT Conduit outdoors

I don't think you can run NM in conduit unless you are under the 2005 version.

[ August 11, 2005, 03:51 PM: Message edited by: petersonra ]

 

[jeff43222]

Re: EMT Conduit outdoors

Originally posted by petersonra:
Are the fittings and boxes being used rain tight? If so, it is acceptable.

Think about it. It would make no sense to have rain tight fittings available for EMT if you could only install them where there is no rain.

see 358.10(C)

<added>
Bonding of EMT in outdoor areas is the same as indoor areas.

My version of 358.10(C) only says that support hardware must be corrosion-resistant in wet locations. It doesn't say anything about fittings having to be raintight.

However, 358.42 specifically calls for raintight couplings and connectors in wet locations.

As for whether it's acceptable to use EMT vs RMC, it's fine as long as the EMT isn't subject to "severe physical damage," according to 358.12(1). Whether the raceway is subject to severe physical damage is an AHJ call. I've read other threads here where some jobs have been tagged when the EMT is exposed to vehicle traffic.

[ August 14, 2005, 07:57 AM: Message edited by: jeff43222 ]

 

[jeff43222]

Re: EMT Conduit outdoors

Originally posted by automaton:
I 100% agree about the fittings, thats why I worded it like that in my question. I thought that this was acceptable, I just wanted to confirm it with you guys. Indeed I plan to ground as if it were indoors, I just wasnt sure if there were any other measures necessary when conduit is going to be directly exposed to natural elements. I plan to run a NM cable from panel to conduit leading to a 90 or elbow, then 10' up to a round box external mounted with water tight seal. I figure I will have to add a ground to properly ground the conduit and box. I am really tired right now, so I am not sure if I explained that well. Does this sound acceptable?

You can't use NM outdoors, even if it's in conduit. NM is only permitted in "normally dry locations" and is prohibited in areas subject to excessive moisture or dampness. Most AHJs consider the outdoors subject to excessive moisture or dampness. Why not run NM from the panel to a j-box where the conduit begins, then run THWN from that point on?