Critique my wiring plan...

[keating]

Sorry, another compressor thread, but I'm settled on size. I just want some feedback on my plan.

I'm installing a 60 gallon / 3.2 "running" hp compressor.
(Older version of this Husky branded CH, when they were red and had a V-Twin pump rather than the parallel twin)

Photo of motor plate is attached.
Confusing:
Says 15A, though not "FLA".
2.98KW converts to 3.99HP (despite description of 3.2 running HP / 5 peak HP)
240V @ 15A =3600W or 4.8HP
This thing is all over the place...

Regardless, 125% of 15 is 18.75A. I could probably get away with #12 and 20A (or 30A) breaker, but why cheap out? Plus, for inspectors' sake, i'd just as soon use "typical" AWG/breaker size. Not much difference in cost.
Main panel and compressor are both in basement of house.
Compressor is just about 5' from the garage footing.
Panel is about a 20' run from compressor.
(compressor is in the middle, between panel and garage)

Current plan is as follows:
30A breaker in panel. (compressor ran off of a 40' long 12/2 NMD90 "extension cord" on a 30A breaker for years in a hack install at previous home)
10/2 NMD90, 20' or so from panel to j-box attached to ceiling joist next to compressor.
From J-box, transition with Marrettes to #10 THHN in 1/2" EMT about 5' run between ceiling joists through rim joist into garage, to LB box, up wall to switch box.
Leviton MS302 switch, then back into conduit, returning to junction box, and transition to Sealtite whip (or via marrettes to MC) to pressure switch (premounted on compressor).

I originally planned to use all 10/2 NMD90, except the whip end, but figured I would need to bump the conduit up to 3/4" to fit, since the wire would be doubling back, and 2x 10/2 NMD90 = 6 conductor (and 1/2" EMT allows a max of 5 #10 conductors, not to mention the extra sheath of the NMD).
Since it's such a short, straight shot to the garage from the compressor location, I figured I could run it all with a single 10' stick of 1/2" EMT and 4x #10 THHN for the hots to/from the switch and a single #12 THHN green insulated ground.
I would use viration proof, set-screw type, 2-piece Marette connectors for the splices.

Questions I have...
Does anyone have a better idea than transitioning from solid (10/2 NMD90) to stranded (#10 THHN) with Marrettes in the J-box?

I've never used THHN (stranded) on screw terminal devices before. Would it be beneficial to tin the ends?
My understanding, (from synopsis, but I can't find the specifics) per 110.14(A) is that the stranded wire can just be twisted and clamped to screw terminals with retainers..more than 2/3, less than full wrap. I hate strands and even tin the ends of my speaker wire connections to avoid stray whiskers.

On the way back to the compressor. is it better to install a Sealtite whip (flex conduit) and continue the THHN through it to the pressure switch? or transition back to solid 10/2MC at the junction box and run MC to the pressure swtich? I'm leaning toward the former. Stranded wire is better in the flexible section, and eliminates a splice.

Thanks for your patience.

 

[keating]

96 views, and 0 responses. Must be a record for a compressor wiring thread.

I'll have to assume I got it all mostly right, or at least correct enough to run the compressor without burning the house down. LOL

 

[wyliesdiesels]

Youre in Canada and most of us sparkies on here are from the states and dont know canadian code....though i hear its similar...might have to be patient and wait a little longer...

 

[keating]

Ah, we just use the same code book as you guys, mix around a few numbers, spell center as centre, labor as labour, and translate it to french.

safe is safe.

Now for my other project, I just need to find a 100A GE Powermark panel. (prefer to match my main panel and pool subpanel).
$57 in a kit with breakers from the US, but not CSA approved for use in Canada.
I'm sure it'll end up costing me $57 for the panel and $100 for the CSA sticker.

 

[keating]

I'm going to bump this once, to see if anyone north of the border has any input.

I won't make it a habit...

 

[Charles (in GA)]

I think you have way too many transitions and connections/splices in the circuit. Not sure in Canada, but in the US, you need a disconnect within sight of, and no more than 50 ft of the equipment. Not sure if the compressor is in sight of the breaker panel or not from your description.

If you are bent on having the switch remote from the compressor, I would attempt to carry the NM all the way to the switch, or run conduit all the way and use THHN all the way, probably easier, #10 NM will be a bear to work with in a box (solid wire).

In mounting the switch, I would use a deep 4x4 box with a front plate to mount the switch, you will need all the room you can get in the box.

Every splice or connection is a potential problem point in the future.

Charles

 

[keating]

I think you have way too many transitions and connections/splices in the circuit. Not sure in Canada, but in the US, you need a disconnect within sight of, and no more than 50 ft of the equipment. Not sure if the compressor is in sight of the breaker panel or not from your description.

It's about 20 ft of wiring, and it will be a contorted path, but you can probably stretch your arms out and touch the compressor and the breaker at the same time

If you are bent on having the switch remote from the compressor, I would attempt to carry the NM all the way to the switch, or run conduit all the way and use THHN all the way, probably easier, #10 NM will be a bear to work with in a box (solid wire).

I'm well aware. I've wired ranges, welders and hot tubs...
I want a double pole disconnect. That's pretty much standard in any installation, is it not? It's only about 20 ft total, of extra wire to the switch position and back, vs. putting the switch next to the compressor.
I think it's safe to be able to shut the compressor down from where I'm working. The garage is just on the other side of the wall from where the compressor is located, but if the compressor needed to be shut down for any reason, it would be a long run through the living room, dining room, down a winding staircase and all the way back through the basement to get to the compressor to either shut off the breaker or the pressure switch

I could run conduit w/ THHN from the panel to the compressor, but it would be no less than 8x 90 degree elbows. Pretty awkward, and it's all in the basement ceiling, which is why I want to use NM.
I want (need?) conduit in the garage for physical protection. I could continue NM in the conduit to the switch and return on THHN all the way to the compressor.
Then the only splice / connection would be the switch itself, but it would require 3/4" conduit to accommodate the NM and the extra insulated ground I would need to run.

Switching from NM to THHN at the compressor point would only be one splice.

In mounting the switch, I would use a deep 4x4 box with a front plate to mount the switch, you will need all the room you can get in the box.

I'd planned to use a double gang utility box with the double switch plate with switch in one side and power indicator lamp in the other

Every splice or connection is a potential problem point in the future.

My plan is really only one splice aside from the switch.
1/2" conduit with 4x THHN + insulated ground

Panel - 20ft NM - j-box splice - 10 ft THHN - Switch - 13 ft THHN- compressor

Alternatively...no splice, with 3/4" conduit to accommodate the NM, THHN + insulated ground.

Panel - 30ft NM - Switch - 13 ft THHN- compressor


Thanks for your feedback.

 

[zmaxmotorsports]

Ah, we just use the same code book as you guys, mix around a few numbers, spell center as centre, labor as labour, and translate it to french.

safe is safe.

Now for my other project, I just need to find a 100A GE Powermark panel. (prefer to match my main panel and pool subpanel).
$57 in a kit with breakers from the US, but not CSA approved for use in Canada.
I'm sure it'll end up costing me $57 for the panel and $100 for the CSA sticker.

Im never been a ge fan myself anyway

 

[zmaxmotorsports]

Can you post a picture of the panel and compressor,and the area in between?

 

[keating]

Im never been a ge fan myself anyway

Wouldn't be my first choice, but just for consistency, it would be nice to have a common breaker in my 3 panels.
They're common in homes around here and the breakers are cheap, and common at the big box stores but no one seems to carry the panels.
I'll have to check with some companies that supply the trades, else I'll go with the most available. Likely a SquareD Homeline

 

[keating]

Can you post a picture of the panel and compressor,and the area in between?

will do... first thing tomorrow.

 

[keating]

Here you go.
The first picture is in the low ~6.5' ceiling area (under the house front entrance).
The compressor is more or less in its final position there.
It can't go any farther into the corner, as it is as close to the HVAC trunk as I want it, to allow for maintenance, and its too tall to fit below the trunk.
The garage is on the other side of the wall to the left of the photo (behind the HVAC trunk and the box of duck decoys there.
My intent was to mount the j-box on the joist above the compressor and run the conduit w/ THHN to the left, to the garage, above the HVAC trunk, and NM to the right, toward the main panel.

This one is looking from the compressor to the main panel behind the freezer and fermentor buckets.

 

[wyliesdiesels]

In the US u would need 3' of clearance infront of that panel, not that the code Nazis would be pounding on your door!

 

[keating]

In the US u would need 3' of clearance infront of that panel, not that the code Nazis would be pounding on your door!

Yeah, just an old freezer that needs a new start relay to turn it into a kegerator...it doesn't belong there permanently.

 

[600SL]

I would go direct from the box with 1/2" or 3/4" EMT transition to flex conduit at the compressor. and just run 2 #12 THHN conductors plus 1 ground right to the compressor switch and use a 30 amp CB. No need for a disconnect since the box is in sight. I believe I heard Canadian codes now require a ground.

My 3.7 HP Lows compressor recommends #12 wire with a 30 amp CB.