EMT as service entrance

[chevss]

Can anyone tell me when emt was last legal as service entrance use? Specifically on a 200 amp overhead meter base. Thank you, Shane

 

[Dennis Alwon]

It is still legal but not as a mast- thru the roof- but as a riser it is fine. Some areas may have a power company rule that may not allow it but by the nec it is compliant

 

[buzzbar]

Washington State prohibits the use of EMT for service conductors. I don't know if or when it WAS legal.

 

[hillbilly1]

Had a service call on one earlier this year, brand new store, overhead service, store manager said water was running out of the panel inside. The contractor that installed it failed to tighten the compression connector in the top of the meter base. Rainwater filled up the meter base high enough to flow into the pipe that entered the bottom, then filled up the LB, then into the bottom of the panel!

 

[480sparky]

EMT had various limits for interior wiring. It changed from a maximum conductor size of #8, then #4, then #0. By 1940, those limits had been removed. 2" was also the maximum size allowed back in those days.

 

[masterinbama]

Decatur AL limits EMT to 600 volts and below.

 

[A/A Fuel GTX]

Washington State prohibits the use of EMT for service conductors. .

I wonder what the reason is? Do they allow PVC?

 

[tom baker]

I wonder what the reason is? Do they allow PVC?

EMT can not be used for service entrace conductors (one exception for existing installed prior to 1960 or so) due to the high level of fault current. There are only 8 allowed wiring methods for service entrance conductors including PVC. The distance inside a building is limited to 15 ft of raceway, this is rather generous.

 

[renosteinke]

The fly in the ointment when you use EMT for any part of a riser is ... the hub atop the can. The hub has tapered threads, and will not properly seat an EMT connector, which has straight threads. You're kind of defeating the purpose of the weathertight hub.

I just don't get this 'fear of rigid.' Add in the cost of the connector, and EMT is no bargain.

 

[iwire]

EMT can not be used for service entrace conductors (one exception for existing installed prior to 1960 or so) due to the high level of fault current.

This is a ridiculous rule they have, the fault current is also above the ability of RMC to handle.

 

[kwired]

Had a service call on one earlier this year, brand new store, overhead service, store manager said water was running out of the panel inside. The contractor that installed it failed to tighten the compression connector in the top of the meter base. Rainwater filled up the meter base high enough to flow into the pipe that entered the bottom, then filled up the LB, then into the bottom of the panel!

I find that very hard to belive. 1. In many places you will see more water inside the raceway because of condensation on a near daily basis than may ever leak through a set screw fitting if one were installed. 2. Unless the meter can was something other than type 3R enclosure (I have never seen one that was not), there are drain holes in the bottom corners of the can and it will never fill up with water to any level unless it is really coming in fast, and I don't think a loose compression nut is going to leak that fast even if in a similar condition to being submerged.

Washington State prohibits the use of EMT for service conductors. I don't know if or when it WAS legal.

I wonder what the reason is? Do they allow PVC?

I don't know why anyone would want to use EMT as a service conductor, and PVC makes a horrible conductor period.:lol:

This is a ridiculous rule they have, the fault current is also above the ability of RMC to handle.

Fault current is going to be different on every service. Ability to handle it - I agree even RMC may not handle it in some cases. Yet they allow SE cable to be run (with no overcurrent protection on supply side) through combustible building materials to get to the service disconnecting means. I would still prefer EMT over SE cable.

 

[hillbilly1]

I find that very hard to belive. 1. In many places you will see more water inside the raceway because of condensation on a near daily basis than may ever leak through a set screw fitting if one were installed. 2. Unless the meter can was something other than type 3R enclosure (I have never seen one that was not), there are drain holes in the bottom corners of the can and it will never fill up with water to any level unless it is really coming in fast, and I don't think a loose compression nut is going to leak that fast even if in a similar condition to being submerged.





I don't know why anyone would want to use EMT as a service conductor, and PVC makes a horrible conductor period.:



Fault current is going to be different on every service. Ability to handle it - I agree even RMC may not handle it in some cases. Yet they allow SE cable to be run (with no overcurrent protection on supply side) through combustible building materials to get to the service disconnecting means. I would still prefer EMT over SE cable.

I was there when it was leaking, a stream of water about half the size of a pencil was flowing out of the bottom of the panel. Opened the LB outside and let it drain out there.

 

[kwired]

I was there when it was leaking, a stream of water about half the size of a pencil was flowing out of the bottom of the panel. Opened the LB outside and let it drain out there.

I don't question that it was leaking, but there had to be more than just a loose compression nut allowing that kind of volume in, and why did it accumulate in a 3R enclosure is another really good question?

 

[iwire]

Fault current is going to be different on every service.

It sounds like the rule applies generally so I was speaking generally.


Below 4" RMC with 600 kcmil copper service conductors.

The locations specific characteristics may increase the likelihood of various results.

 

[hillbilly1]

I don't question that it was leaking, but there had to be more than just a loose compression nut allowing that kind of volume in, and why did it accumulate in a 3R enclosure is another really good question?

It was an unusual 320 amp meter base, I don't know where they got it from, but it was sealed with what appeared to be a gasket on the cover, and no drain holes in the bottom. I was not about to blind drill any in it!

 

[kwired]

It sounds like the rule applies generally so I was speaking generally.


Below 4" RMC with 600 kcmil copper service conductors.

The locations specific characteristics may increase the likelihood of various results.

Exactly why service conductors are supposed to hit the service disconnecting means pretty much ASAP when entering a building.

Now just how much more damage may have been done if the wall were combustible material?

Though it was code compliant installation, if that were a new installation today those service conductors would likely be routed into the ground as quickly as possible instead of having so much exposure on the building surfaces.

I know you know this, but some readers may not.

 

[iwire]

Exactly why service conductors are supposed to hit the service disconnecting means pretty much ASAP when entering a building.

Now just how much more damage may have been done if the wall were combustible material?

Though it was code compliant installation, if that were a new installation today those service conductors would likely be routed into the ground as quickly as possible instead of having so much exposure on the building surfaces.

I know you know this, but some readers may not.

That was installed around 2004, blew up shortly after. There is a pad mount transformer supplying these conduits, from there they run underground, up and across the wall and directly into the rear of the switchgear on the second floor.

In this area we are still doing the same installations today.

 

[kwired]

That was installed around 2004, blew up shortly after. There is a pad mount transformer supplying these conduits, from there they run underground, up and across the wall and directly into the rear of the switchgear on the second floor.

In this area we are still doing the same installations today.

I suppose it can be somewhat a regional thing, and if building in an older developed area changes things at times. But almost all the new stuff around here on previously undeveloped land gets service buried right to point where it enters the building or only has vertical exposure before entering. But where you are, there is likely not nearly the previously undeveloped property as there is here either.

 

[iwire]

The NEC does not have any limit on service raceway / conductor length outside a building. Life is good.

 

[paul]

EMT is allowed in WA state for service conductors. It is not allowed once those conductors head inside the building.

Per WAC 296-46B-230-43
(8) Electrical metallic tubing must not be installed as the wiring method for service entrance conductors inside a building. Existing electrical metallic tubing, installed prior to October 1984, which is properly grounded and used for service entrance conductors may be permitted to remain if the conduit is installed in a nonaccessible location and is the proper size for the installed conductors.