SINGLE PHASE 4 WIRE 120/240 OUTDOOR UNDERGROUND FEEDER TO A SUB PANEL

[Eddie702]

Homeowner is removing a hot tub and wants me to use the existing 40-amp feeder 3#8s and a #10 insulated ground and mount a 3R subpanel on a post where the hot tub was.

Reading 215.9 It looks like GFCI can be the feeder breaker in the house or the branch circuit breakers in the outdoor sub.....is that correct? No requirement for the feeder itself to be GFCI protected?

My only other question is does this require a ground rod?

If 250.32 and the exception says what I think it does it needs one because they would allow a multi wire circuit to run out there without a ground rod if it was a branch circuit but not if it's a feeder.

Do I have that right?

 

[Seven-Delta-FortyOne]

Feeder is not required to be GFCI protected.

GECs are required at separate structures if supplied by a feeder.

The single circuit exception would need to be GFCI protected from the panel, but you are limited to 15 or 20 amp receptacles only IIRC

 

[LarryFine]

All correct.

 

[kwired]

Feeder is not required to be GFCI protected.

GECs are required at separate structures if supplied by a feeder.

The single circuit exception would need to be GFCI protected from the panel, but you are limited to 15 or 20 amp receptacles only IIRC

I don't believe there is a 15/20 amp restriction, 50 amp RV receptacles (or similar situations) are on separate structures (like a post) all the time without a grounding electrode.

 

[Seven-Delta-FortyOne]

I don't believe there is a 15/20 amp restriction, 50 amp RV receptacles (or similar situations) are on separate structures (like a post) all the time without a grounding electrode.

Now I gotta go actually read the Code article.

Must have been thinking of running a single circuit to a garage, for lights and receps.

 

[Dennis Alwon]

Is the post detached from house?then it needs rods

 

[kwired]

Now I gotta go actually read the Code article.

Must have been thinking of running a single circuit to a garage, for lights and receps.

I didn't read either before posting.

Another common one is you could have 50 amp lighting circuit to several poles, but is still a single branch circuit to those structures and not a feeder circuit. Many those seem to get ground rods by specification, but NEC doesn't require them.

 

[augie47]

You have a situation where definitions are important. As far as the Exception in 250.32 it applies to branch circuits. As others have noted you have a feeder so that exception does not apply.
That said, 250.30 requires a grounding electrode at "Buildings or Structures" and the '17 Code changed the definition of a structure to include the wording "other than equipment". Inspectors seem to vary on enforcement as to what you have being considered a "structure"
(To me it is equipment mounted on a post but, as seen, Dennis and others look at it otherwise)

 

[kwired]

You have a situation where definitions are important. As far as the Exception in 250.32 it applies to branch circuits. As others have noted you have a feeder so that exception does not apply.
That said, 250.30 requires a grounding electrode at "Buildings or Structures" and the '17 Code changed the definition of a structure to include the wording "other than equipment". Inspectors seem to vary on enforcement as to what you have being considered a "structure"
(To me it is equipment mounted on a post but, as seen, Dennis and others look at it otherwise)

gets tricky sometimes if you want to be strict with definitions.

For years I have done grain bin storage sites where we have the service, distribution, controllers, etc. items on a post, free standing rack, or even in a small shed mostly dedicated for electrical components, then run circuits to individual loads on the bins, which are technically separate structures.

If you have transfer equipment between bins, or between bins and an elevator leg, I guess that kind of ties them together making them a single structure in a way. But that isn't always the case, is more common at a commercial elevator than is on the farm though. At same time if you have them all wired up as separate structures then add transfer equipment to something existing, you now have multiple feeds to a single structure and technically need to redo all that had been done before to be code compliant?

 

[Eddie702]

Is the post detached from house?then it needs rods

That's the way I read it. TY

 

[Eddie702]

The code is way too confusing when 6 or 7 of us who read the code come up with different answers. I guess the question is "what is a structure"

"That which is built or constructed, other than equipment"

It would seem to me that a post would be a structure.

What safety is gained by a ground rod when the feeder has an insulated properly sized equipment ground?

Is it the length of run they are concerned with?

It would be allowed with a multi wire branch circuit but not with a feeder

 

[kwired]

The code is way too confusing when 6 or 7 of us who read the code come up with different answers. I guess the question is "what is a structure"

"That which is built or constructed, other than equipment"

It would seem to me that a post would be a structure.

What safety is gained by a ground rod when the feeder has an insulated properly sized equipment ground?

Is it the length of run they are concerned with?

It would be allowed with a multi wire branch circuit but not with a feeder

One can kind of argue whether having a rod at the main structure with the service disconnect actually makes things safer as well, but I don't see NEC changing the requirement of a GES there anytime soon. The supply side of the service is well grounded in most MGN distribution systems, that one electrode at your house doesn't normally mean much, means more in a direct lightning strike, but isn't exactly lightning protection either.

 

[jap]

I'd take the neutral pigtail from the 2p 40a GFI breaker in the main panel off and cap it,,,,, re-route the feeder neutral directly to the neutral bar in the main panel,,,, stick a rod in the ground at the post location with a GEC to the ground bar in the subpanel and let it roll.

JAP>

 

[mtnelect]

When I was doing traffic signal work for the County of Los Angeles, we started converting our controllers from electromechanical to digital. We were installing "170 Controllers" which were all solid state. Our electrical service started on a utility pole and went underground to the controller where we installed a second ground rod. After installing several cabinets, we started getting calls that the intersections were going on "Flash". I discovered that there was a difference in potential between the two ground rods. So, I disconnected the second ground rod at the controller cabinet and pulled a grounding conductor back to the service, and that corrected the problems.

 

[jap]

When I was doing traffic signal work for the County of Los Angeles, we started converting our controllers from electromechanical to digital. We were installing "170 Controllers" which were all solid state. Our electrical service started on a utility pole and went underground to the controller where we installed a second ground rod. After installing several cabinets, we started getting calls that the intersections were going on "Flash". I discovered that there was a difference in potential between the two ground rods. So, I disconnected the second ground rod at the controller cabinet and pulled a grounding conductor back to the service, and that corrected the problems.

That's not a correction,,,, that's a miracle.

JAP>

 

[tom baker]

That's not a correction,,,, that's a miracle.

JAP>

Was there originally an EGC between the service and TS cabinet?

 

[mtnelect]

Was there originally an EGC between the service and TS cabinet?

No ... At that time, the consensus was the rigid conduit would provide the necessary grounding. But with the introduction of solid state a different mindset was needed.

 

[retirede]

No ... At that time, the consensus was the rigid conduit would provide the necessary grounding. But with the introduction of solid state a different mindset was needed.

As long as the raceway was still intact, adding a wire EGC did nothing.