EMT for overhead service

[zcanyonboltz]

I have always used rigid for overhead service entrance conductors. I was out walking the dog and noticed a few houses in the neighborhood that have EMT for the service mast. I looked through articles 225, 230, 358 and found nothing that prohibits EMT being used for service entrance conductors. Is there a requirement that service entrance conductors must be in GRC? I always took for granted putting service entrance conductors in rigid conduit without much thought. Thanks

 

[augie47]

As long as the riser is not used for support of the service drop there is no NEC problem. A lot of POCOs have their own requirements.
(If the conduit is used to support the drop the NEC simply says "adequate strength" but I know of no POCI that would accept EMT if the drop is tired to it.)

 

[infinity]

Unless the raceway is supporting the drop from the pole you can use EMT. Some have an issue with screwing an EMT connector into the hub of a meter pan since the hub is designed for RMC which has tapered threads.

 

[hillbilly1]

I went behind an emt service riser install, Dollar General, customer called in an emergency call saying water was flowing out of the panel. Brand new store, monsoon rain storm. Sure enough, water was flowing out the panel. Opened the panel, water was coming into the back. Went outside, opened the LB, water poured out. Opened the meter can, water was flowing thru both hubs on top. EMT compression connectors. I was talking to my continuing education instructor (he is on the NEC CMP) and said EMT connectors are not compatible with hubs, just as Infinity said, the threads are not tapered.

 

[Another C10]

I have always used rigid for overhead service entrance conductors

Typically the last 10 feet to the weather head, lets say of a 15' or 20 ' riser needs to be rigid in Cal. I agree though even still, l run the whole riser in Rigid.

 

[zcanyonboltz]

My buddy is telling me to use a Myers Hub with EMT. In reading about them though they say these are for IMC and RMC which may present the same issue as an EMT compression fitting in a hub.

 

[infinity]

My buddy is telling me to use a Myers Hub with EMT. In reading about them though they say these are for IMC and RMC which may present the same issue as an EMT compression fitting in a hub.
View attachment 2552113

Yes they have the same technical issue. Same goes for an SE cable connector. As I said before this is dumber than dumb.

 

[electrofelon]

I have done risers with EMT. I prefer it much more that PVC. The EMT connector into hub thing is a technicality I dont think anyone cares about. Using EMT over RGS depends on the situation. Often you will find that after you factor in rain tight couplings (particularly in larger sizes), you wont end up saving much over RGS.

 

[zcanyonboltz]

The cost of 10' RMC 2" is about $55 a stick and 10' EMT 2" is about $23 with a 2" compression connector being about $5. The savings is around $27 if just using 10' of conduit and one compression connector.

 

[zcanyonboltz]

Of course the more conduit and couplings needed the savings will increase. For a job as important and costly as a service upgrade l will continue using rigid.

 

[zbang]

Of course it'll be different around the country, but you're less likely to get arguments from the AHJ with rigid (whether they're correct or not). (Like a second ground rod- even where it's not really needed (per code), it's often easier to install one than argue the point.)

 

[electrofelon]

The cost of 10' RMC 2" is about $55 a stick and 10' EMT 2" is about $23 with a 2" compression connector being about $5. The savings is around $27 if just using 10' of conduit and one compression connector.

Make sure you are looking at rain tight fittings. The larger sizes like 3-4" is when they get pricey and chew thru some of the savings. I did an 800 OH service with 2 4" EMT's once, and it turned out RGS wouldn't have been much more, although a lot harder on the back!

 

[jaggedben]

A big local jurisdiction I started out in prohibits EMT for service entrances. I was a little surprised to find out it wasn't in the NEC.

 

[kwired]

I went behind an emt service riser install, Dollar General, customer called in an emergency call saying water was flowing out of the panel. Brand new store, monsoon rain storm. Sure enough, water was flowing out the panel. Opened the panel, water was coming into the back. Went outside, opened the LB, water poured out. Opened the meter can, water was flowing thru both hubs on top. EMT compression connectors. I was talking to my continuing education instructor (he is on the NEC CMP) and said EMT connectors are not compatible with hubs, just as Infinity said, the threads are not tapered.

True the hubs are intended and listed for use with tapered threaded conduit, but a straight thread fitting will fit tight enough you likely have little leakage or even no leakage. My guess is improper drip loop in the conductors allowed water to follow conductors right into the weatherhead. Some cases even can have splicing method to the drop conductors allow moisture inside the conductor insulation and it follows conductor inside insulation right into meter socket or into your main breaker if there is no meter socket. This won't happen if the splicing connector is below the weatherhead but can if it is above the weatherhead.

 

[electrofelon]

A big local jurisdiction I started out in prohibits EMT for service entrances. I was a little surprised to find out it wasn't in the NEC.

WA doesnt allow EMT for service conductors inside a building

 

[Another C10]

My buddy is telling me to use a Myers Hub with EMT

I've used Meyers hubs on exterior panels with the compression connector landing on the meyers, I always made sure to use noalox or a weather proofing compound on the threads to assure no seepage.

 

[readydave8]

I've used Meyers hubs on exterior panels with the compression connector landing on the meyers, I always made sure to use noalox or a weather proofing compound on the threads to assure no seepage.

Does noalox on threads seal out water? Or do you do that because that's what you've always done?

 

[norcal]

The ultimate authority is still the PoCo, for example SE cable is a code compliant method, but PG&E will not accept it.

 

[kwired]

I've used Meyers hubs on exterior panels with the compression connector landing on the meyers, I always made sure to use noalox or a weather proofing compound on the threads to assure no seepage.

That is what most of us did long time ago before there were "raintight connectors". Unfortunately the rubber washers that come with these "raintight connectors" are crap and will deteriorate within first year in many cases making the "raintightness" pretty ineffective. I still thread them into a myers hub after experiencing this just a few times even though they technically are not listed for this. Haven't had an inspector say a word about it yet. What little leakage you might get through the hub threads is still less than moisture that will condense on inside of the raceway anyway. Maybe in desert southwest you don't get much condensation, here we can have at least some nearly every night, and is worst on the most humid days.

 

[electrofelon]

That is what most of us did long time ago before there were "raintight connectors". Unfortunately the rubber washers that come with these "raintight connectors" are crap and will deteriorate within first year in many cases making the "raintightness" pretty ineffective. I still thread them into a myers hub after experiencing this just a few times even though they technically are not listed for this. Haven't had an inspector say a word about it yet. What little leakage you might get through the hub threads is still less than moisture that will condense on inside of the raceway anyway. Maybe in desert southwest you don't get much condensation, here we can have at least some nearly every night, and is worst on the most humid days.

Yeah and remember there are numerous other code sections that, IMO, make the rain tite thing not necessary. Raceways allowed to drain, weep holes, entries below live parts, etc. I dont remember them all off hand, I compiled a list in one of the anti raintight rant threads a while back.