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I'm looking for feedback on my electrical plans for a hot tub install. The space is in a 7 unit building located in NYC. The apartment is owned, not rented. I am planning on hiring an electrician for this work but I recently decided to go back to school and started a residential electrician course a few weeks ago so I am excited about the industry and curious if there is any work I could try my hand at - or do some of the more manual work that the electrician is probably dreading. Anyways, here is my plan on how I think it could be wired. If someone could point out big flaws, or parts that I can take off the electricians hands I would be excited to try it out.

Here is an idea of the space and design I'm thinking up. None of the work has been started yet so this is all just a hypothetical electrical design that I have came up with. The floor is made up of heavy cement pavers that can be removed. Underneath is a 10" gap mostly filled up with rigid foam.

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The main panel is inside the apartment on the opposite side of the wall from the spa disconnect.

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The hot tub will be located 20 feet from the 60 amp spa disconnect.

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Here is my basic plan of the work required to wire up this tub.

(1) Turn off the main breaker to the apartment (located in basement) and padlock the cover closed while working.

(2) Cut open up an 8x8 inch hole in the interior wall directly below the main panel.

(3) Punch out a new opening in the bottom of the panel case with screwdriver/mallet.

(4) Drill a 3/4" hole through the 12" exterior wall (stucco -> styrofoam insulation -> drywall -> vapor barrier -> cotton candy-like insulation). Here is an image of the hole for a light fixture in the exterior wall.

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(5) Punch out the hole in the back of the spa disconnect with a hammer/mallet and secure it to the exterior wall, lining up the hole in the wall with the hole in the back of the disconnect. weatherproof any gaps with sealant or caulking.

(6) Fish 4 #6 awg wires through the spa disconnect hole, and then through the wall, from the exterior to the interior, and insert them up into the panel.

(7) Snip the wires leaving enough slack to connect them to the spa disconnect and panel + a little bit extra length. Remove a bit of the insulation at the tips.

(8) Connect the two hots to the spa disconnect hot lugs, neutral to the neutral lug, and ground to the ground bar.

(9) Back inside, install a double pole 60amp GFCI breaker in the main panel and connect the 2 hots and neutral wire to the breaker. Pigtail neutral to neutral bar, and ground to the ground bar.

(10) I am imagining running the wires directly through the hole in the wall to the spa disconnect. However, checking out the main panel, I noticed that all other wires in the apartment are armored with MC cable. Should I also be using MC cable for this little distance? #6awg MC cable is extraordinarily expensive at Home Depot so I am hoping that this is not the case...

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(11) Lift up all the pavers that need to be moved. This job is a heavy job and definitely one place I can help the electrician out with beforehand by moving them and prepping the space. Connect the 3/4" rigid conduit together to form a length of at least 24 + 16ft. Mark, unscrew, and bend the conduit where necessary with the appropriate 3/4" conduit bending tool. Rigid conduit is threaded so if I need to cut the end off when it reaches the pump housing I am assuming there is a way to connect a cut rigid conduit to an electrical box located inside the housing (compression fitting?). I am not sure how yet but I am researching (the pump housing will be weatherproof so I believe the connection between the conduit and box need not be weatherproof).

(12) I am imagining the conduit attached to the spa disconnect with a weatherproof connection, dropping down beneath the cement pavers, and then running about 24ft along the space, making a 90 degree turn, and then continuing 16ft across the space. Below is a close up of the spa disconnect connection and a cross section of the pavers on the space showing the gap below where I am planning on running the conduit. Inside this gap is foam and cement so I am not sure if the conduit can be secured anywhere along the way. I am hoping this is not a requirement.

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(13) The connection from the spa disconnect to the 3/4" rigid conduit will have a weather proof connector and maybe a weatherproof 90 degree junction box at the big 90 degree turn so that it's easier to fish the wires through.

(14) Secure the conduit where it can be secured and fish 4 #6awg wires through it.

(15) Connect the spa disconnect end of the wires. Two hots and neutral to the 60amp GFCI breaker. Pigtail neutral to neutral bar, and ground to the ground bar.

(16) Finally snip the wires to length. Inside weatherproof pump/filter/heather housing, on one of the walls, install an outlet box and connect the conduit to the box. Since this housing is weatherproof the connection need not be a weatherproof connection.

(17) Connect the wires to the hot tub controller.

Some questions I have are:

  • Should I be using MC cable for the little distance inside the wall from the panel to the spa disconnect or can I just have the wires themselves?

  • Spa disconnect connection to the 3/4" rigid conduit must be weatherproof, right?

  • Should I install a weatherproof junction box at the 90 degree bend?

  • Does the conduit need to be secured to something underneath the pavers?

  • Can I connect the cut end of a 3/4" rigid conduit to an outlet box with a compression fitting? Does not need to be weatherproof.

  • Which parts of this plan would be a good idea for me to do myself?

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    I'm pretty sure that in NYC the THHN has to be in conduit through the wall. Use an LB at the bottom of your panel with a piece of 3/4 EMT through the wall and directly into your disconnect. – JACK Sep 20 '20 at 19:13
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    @JACK the LB will require perpetual access to the access hatch on the LB without disassembling any part of the building. Can't bury an LB, can only bury a sweep. One can also come out the back of a panel... – Harper - Reinstate Monica Sep 20 '20 at 19:58
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    @JACK how would you ever pull through it? Can’t pull around a conduit body, that’s why they have access covers. – Harper - Reinstate Monica Sep 20 '20 at 20:24
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    @Jack good point, I have seen sharp elbows right at the panel where you can manipulate it, ie push as fast as it’s pulled so it’s never dragged round the corner. But they make special fittings for that, you don’t use LBs. – Harper - Reinstate Monica Sep 20 '20 at 21:00
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    @Ed +1 on a nipple straight out the back, no bend. the pavers are not on bare ground, this is NYC, there is no bare ground! They are on insulation that is on somebody else’s roof. – Harper - Reinstate Monica Sep 20 '20 at 21:05
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In step #9 you mentioned putting a 60 amp gfci breaker in the main panel. I believe the hot tub disconnect has a 60 amp gfci breaker in it already. Put a 60 amp 2 pole breaker in the main panel!! It will be about 1/5 the cost of a gfci breaker

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