Outside Recepticle and Outside Light

[gbeichho]

Location: Ontario, Cottage

I was planning to add a new external dual recepticle to the outside of my cottage. I was also planning to use this same circuit to power an outside post with another recepticle, and sensor light at the driveway (along with a separate circuit for 30A RV recepticle. Here are my options and questions:

1) Am I able to put a 20A outside recepticle as long as it is GFI protected and is a dedicated ciruit? (yes I think)
2) If I run a 20A circuit to these two GFI protected dual recepticles, can I use the circuit to power the light on the post? (No I think)
3) If I run a 15A circuit to these two outdoor GFI protected dual recepticles, can I run the outdoor light on the same ciruit on the post? (I don't think so, but that seems stupid)
4) Can I use a wooden post? Do I have to run a special ground wire inside my conduit? (I read something confusing in Knight's book)

I've read Knight's book electrical code simplified, and he states that circuits for outdoor recepticles must be separate. I'm not sure but this seems to prevent me from adding a light to my post off the same circuit as the recepticle.

I'm also assuming I have to run the 10/3 wire (for RV recepticle) and the 15/2 or 12/2 wire in separate PVC conduits?

Thanks,

George

[Homer]

1) Am I able to put a 20A outside recepticle as long as it is GFI protected and is a dedicated ciruit? (yes I think)
Yes, all outdoor receptacles must be on a circuit dedicated for outdoor receptacles. You could have up to 12 outdoor receptacles on a single outdoor receptacle circuit.


2) If I run a 20A circuit to these two GFI protected dual recepticles, can I use the circuit to power the light on the post? (No I think)
No, only outdoor receptacles are permitted on an outdoor receptacle circuit.



3) If I run a 15A circuit to these two outdoor GFI protected dual recepticles, can I run the outdoor light on the same ciruit on the post? (I don't think so, but that seems stupid)
No, only outdoor receptacles are permitted on an outdoor receptacle circuit. You could run a 15A multiwire circuit and use the one side for receptacles and the other for the luminaire. You couldn't use a 20A multiwire circuit for this because all luminaires must be on 15A circuits only (30-104A).


4) Can I use a wooden post? Do I have to run a special ground wire inside my conduit? (I read something confusing in Knight's book)
I know of no reason to why you can't use a wooden post. You will need to run a grounding conductor in the PVC conduit for each circuit. It needs to be 14 AWG for a 15A or 20A circuit and 12 AWG for a 30A circuit. These are different wire sizes than for NEC requirements. Remember, you're running individual conductors (T90 / TWN75 dual listed) in the conduit not a cable, so you need to provide the grounding conductor. For your info the NEC requires the grounding conductor to be the same size as the current carrying conductors for a 15A, 20A, and 30A circuit (#14, #12, & #10 respectively).


I've read Knight's book electrical code simplified, and he states that circuits for outdoor recepticles must be separate. I'm not sure but this seems to prevent me from adding a light to my post off the same circuit as the recepticle.
Yes, see my earlier comments.


I'm also assuming I have to run the 10/3 wire (for RV recepticle) and the 14/2 or 12/2 wire in separate PVC conduits?
Yes, or else you would need a large sized conduit to satisfy the fill requirements on top of the issue of having to derate the ampacity of the conductors.

Homer

[Homer]

To be complete I will give you another alternative to the PVC conduit solution. You can always use NMWU cable (rated for direct burial). You can bury this cable without conduit and use conduit only for physical protection where you exit through the wall (with an LB fitting) and where you enter the post/fixture.

I believe that your confusion must be from reading pieces from both methods (individual conductors in a complete conduit system vs direct burial cable) in your book. With a conduit system you need to add a grounding conductor while with direct burial you already have it in the cable.

Just a reminder, you can't run NMD90 cable even in an underground complete conduit system. It's not rated for WET conditions. NMWU cable is rated for WET conditions.

Homer

[gbeichho]

This makes more sense now. Can I use NMWU wire in a conduit so I can bury it at 17"? In this scenario, do I need a separate grounding conductor?

As I understand it, my other option for 17" depth is cedar planks.

Thanks,

George

[Homer]

This makes more sense now. Can I use NMWU wire in a conduit so I can bury it at 17"? In this scenario, do I need a separate grounding conductor?

As I understand it, my other option for 17" depth is cedar planks.

Thanks,

George
You can use the conduit or the planks to protect against physical damage. Some will frown upon using cable in a complete conduit system as it is overkill but it can be done in this situation since the entire run is subject to damage.

If you do use cable (NMWU) then it already has a grounding conductor in it. If you use individual conductors (black, white) then you need to pull a grounding conductor as well (green or bare).

Homer