THWN wire; Gray pvc Conduit; and GFCI receptacles

Buzzy

I've trenched down 18" and placed the 3/4" gray PVC piping in position. I Went to my local home improvement center to buy the wire. I understand that there are some wires that have what seems to be a dual rating: THHN (high heat resistant) and THWN (heat & water resistant).

The particular brand that is in stock is the SIMpull romex type NM-B for indoor applications; manufactured by the South Wire Co.; it is obviously not rated for wet locations- I verified this at their web site- the wire is a THHN rated wire; contrary to what the clerk working in the electrical department of the home improvement center said. He recommended that I could still use the wires by stripping the outer sheathing and running the wires through the conduit.

My first question is, should I trek over to an electrical supply house and buy the single solid strand of THWN of each gauge wire (by color, e.g black, white, & green) to be code compliant?

Does the ground wire have to be coated or can it lay bare in the conduit? (Remember, if I follow the store clerk's instructions- predicated that his wire was THWN rated, I would be sleeving a bare copper wire through the conduit- where condensation will build up at the very least.)

RE: the receptacles, should they both be GFCIs (exterior rated, of course)?

Thanks in advance! ~Buzzy

ddawg16

Welcome to DIY...

First off....you don't want to be pulling any type of romex through conduit.....while it can be done, it's not easy and sort of defeats the purpose of the conduit....especially 100'.

Get some THWN stranded wire (all 3 colors) and pull that through the conduit. The rolls will likely come in 500' lengths, so it if was me...I would just use the same wire for the lamps instead of using 14awg. As fas as I know, it's ok to use 12awg on a 15A breaker. You just can't go the other way around.

Is the conduit going straight to your load center? If so...makes life easier....just terminate the wire in the load center.

However, on the load side...using stranded wire takes an extra step or so. Lights are easy...wire nut....but on the outlets, unless it is the type with a back plate on the screw, then you either have to use a pigtail with solid wire to the outlet or crimp connectors on the wire and then the connector screws to the outlet.

Personally....I prefer the crimp connectors if it's just one connection...but if your branching off to more than one outlet....then pigtail it.

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k_buz

You cannot use romex (NM), or the conductors inside the outer sheathing underground or outside. You will need to purchase individual THWN. The ground can be bare, but I would purchase a green #12 for the run.

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Code05

Not correct, UL lists receptacles for both solid and stranded conductors.

Twist strands CCW and they terminate just fine on screw terminals.

ddawg16

Yea....I know....but I've had a couple of times where one strand 'stood out' and created a problem......

Personally....the only way I would attach a stranded wire to the screw terminal without a crimp on connector is if I tinned the wire first. But that is a personal thing.

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Buzzy

Thank you for your replies. I was told the following, " Ground Fault Circuit Interrupter (GFCI) protection for all outdoor receptacles is required
by the NEC – accomplished with an individual GFCI receptacle in each outlet box or with a GFCI breaker mounted in the service
panel that protects the entire circuit."

Any comments or suggestions? I plan on placing a receptacle on the front siding of my house and the other by the lamp post that will light my sidewalk. Is it okay to have two exterior grade GFCI receptacles on the same circuit?

A friend of mine told me that if I place the GFCI receptacle at the beginning of the circuit, it will provide protection coverage to the second receptacle down the line without having to install a second GFCI outlet at the lamp post.

Expense aside, I want to make sure that I am installing these receptacles properly- to code...safety is paramount.

frenchelectrican

You can use one GFCI receptale for both outdoor receptales and it is pretty common to do that just remember the line and load connections just don't get them cross connected otherwise they will not work useally not kick on or stay off.

Are you putting the receptales on the lamp post ? if so which style you are going to use ? that will make the differnce on them. Also with the WP ( weather proof box ) if you going to use the GFCI's use the deep well verison due you will have more room to work around with them. ( they worth extra cost for deepwell verison )

Merci,
Marc

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The answer will be based on NEC ( National Electrical code ) or CEC ( Cananda Electrical code ) or ECF ( Electrique Code France )

Buzzy

Thank you for the heads up- I've installed exterior grade GFCIs in the past; one at the beginning of the circuit to cover the other receptacles down the line. I just never installed one at each location- so I wanted to make sure one did not trip the other.

At one time, I did use a GFCI circuit breaker in the load panel, but every time I would use a power tool or vacuun, the breaker would trip. So I swapped out the breaker and installed a GFCI receptacle and never had any problems.

The lamp post farthest from my house (I'm placing two into place) will have the receptacle. I'm going to build a pillar out of brick and mortar and run a stub out through the brick; and attach the the 2 x 4 weather resistant box to the brick.

As for using a deep well box, I did use one on the original install years ago for the same reasons you specified- but now Leviton makes slim profile GFCIs- and since there will be only three solid core THWN #12 wire in the box, I think there is ample room. Just the same, I had purchased a flanged box extension just in case.

I will be using the following supplies: red dot 3/4" wet location outlet box RIH32LM; if needed red dot 3/4" wet location flanged extension RIHEF6S22; red dot metal weatherproof (while in use) lockable security cover CKMU; and the Leviton 20A weather and tamper resistant slim line GFCI WT899-KW.

How far up from the ground level must the outlet box be placed?

Merci Beaucoup ~

electures

While your at it, you need to install a panel suitable for use as service equipment at each post and drive two ground rods at each as well.

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Buzzy

Could you please elaborate?- I'm not sure of what you mean by this. I appreciate your help.

stickboy1375

I believe he was being funny, because the posts are structures.

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electures

ANy structure supplied by more than one circuit requires a panel rated suitable for use as a service disconnect and ground rods at each structure. A post lamp is a structure. It would be easier to run a multiwire branch circuit with one constant hot and the other switched.

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AandPDan

If you're not in a rush, depending upon your needs you can order 50' or 100' spools of thwn from the big ORANGE box store. It's cheaper than buying it by the foot but still more per foot than the 500' spool.

Buzzy

Please bear with me, If I understand you correctly- for the two 7' residential light poles I'm installing on a 15 amp switched circuit (via an Intermatic ET1725C DPST timer), I have to drive 2-8' ground rods per lamp post and add a service disconnect to an existing exterior receptacle that's attached to my house siding (which is the only receptacle on a 20 amp circuit) because I want to extend that circuit out to a brick post/pillar I am building around the lamp post!?

Buzzy

Thank you sir for replying. Since I did buy individual lengths already, I will need to wrap one of the leads (extra length of white) in green tape to color code it as my ground since the supply house ran out of insulated ground wire. Does the green tape have to cover the wire completely by overlaying the tape to itself or can i just spiral it on leaving gaps where the white insulation will be exposed?