Electric trench in concrete floor?

[imagineer]

I now have a strong dislike for extension cords, despite using them every time I’m in the workshop. It’s not the cords so much, it’s that I am constantly walking across them, or stepping on them. This past week, I ended up tripping badly on a cord, taking a fall and in the course of hitting the shop floor (and puncturing my shoulder), managed to rip the MIG torch cable right off my steel MIG unit.

The 3’ wide pathway where I tripped is between where I park my welders and the weld table. It’s near the electric panel and also there’s a convenient 120v outlet I use for angle grinders, shop vac, etc.

The locations of the welders and weld table have been static for 12+ years (i.e., I don’t foresee having to move the weld table), and for that time span, I’ve been walking across (and tripping on) the extension cords.

I’m thinking of cutting a 4” wide section of the shop concrete floor between the weld table and wall and running 2” PVC conduit in the trench. I’ll pull wire through, and using PVC conduit under the weld tabletop, put in power outlets near the corners of the weld table. I'll concrete over the trench. Is there a reason I shouldn’t do this?

I’ll add that the concrete floor in the pole barn workshop is already in awful shape. It needs to be replaced, but I’m simply too cheap. Cutting a short trench and cementing over it will not diminish the floor or make it any worse.

Regarding the damaged MIG, luckily I have still had the torch cable from the aluminum MIG where I now run a spool gun.

 

[larry4406]

Would overhead drop be easier?

A customer of mine had us install floor boxes in his slab of his shop so he could install outlets for his table saw and shop tools where he wanted them. This was new work installation. PVC conduit and THWN wire. The electrician used GFCI breakers to power the outlets since the conduit is a potentially wet area.

Have also done floor boxes in basement slabs for customer specified floor plug locations. We also did these in PVC conduit with THWN wire. These we ran to a nearby wall outlet and installed a GFCI receptacle there and connected the floor plug to the load side.

 

[Half-fast eddie]

Floor outlets end up being in the wrong place 2 months after installation. Go overhead.

 

[imagineer]

Floor outlets end up being in the wrong place 2 months after installation. Go overhead.

I'm not opposed to this. How do the pull down cord reels hold up?

Many years ago, I watched one short out when the cord was being extended.

 

[Shwoody]

Sounds like a lot of work but I don't see why not. If it was me, I'd do overhead like the others suggested. My (limited) experience with the cheap plastic cord reels was not great so for my garage I bought a couple used commercial style ones on eBay. Another cheaper option could be to do a hanging outlet with SO cord.

 

[Zeke]

If I ever do floor boxes they will be a flush JB upon which I can stub up a short ****** and upright box. IDW anything that will fill with dirt.

 

[nh_yota]

You can always put a fixed drop with a kellem grip instead of a reel.

 

[Norcal]

If I ever do floor boxes they will be a flush JB upon which I can stub up a short ****** and upright box. IDW anything that will fill with dirt.

I have floor boxes in my shop & they have been fine for 30 years.

 

[ycgoat]

Outlets fed from overhead don’t have to be flexible cords. You could run a post down using metal, wood, or a prefabbed power pole.

https://www.gordonelectricsupply.com/p/Wiremold-25Dtp-412Wh-Tpp-Duplex-2-20A-White-12Ft/6624813?gclid=CjwKCAiAwc-dBhA7EiwAxPRylCk0Jxb0r4tTr_QS0TUs5ztJFTIErDWKlUER4rAzcSgJysGackWfoBoCITwQAvD_BwE

 

[imagineer]

Outlets fed from overhead don’t have to be flexible cords. You could run a post down using metal, wood, or a prefabbed power pole.

https://www.gordonelectricsupply.com/p/Wiremold-25Dtp-412Wh-Tpp-Duplex-2-20A-White-12Ft/6624813?gclid=CjwKCAiAwc-dBhA7EiwAxPRylCk0Jxb0r4tTr_QS0TUs5ztJFTIErDWKlUER4rAzcSgJysGackWfoBoCITwQAvD_BwE

I specifically don't want to use a power pole (my shop is relatively small and I'll eventually damage the power pole). It will either be power run under the floor, or retractable cord reels from above.

 

[dcg9381]

I have a friend building a shop right now. He thinks he wants a few floor outlets. My advice was "absolutely not" - they're expensive to put in, your concrete guy may not get them right, and they are at best a great place for **** to collect.

Overhead all the way.

 

[alfredeneuman]

You can always put a fixed drop with a kellem grip instead of a reel.

Kellems aren't the only thing that's listed as a strain relief.
"Gland nut" style cord connectors are as well, and cost a lot less.
Even some 2 screw connectors are rated for both cord and NM (Romex)

 

[nadogail]

I have seen trenches with cover plates, they made modifications easier.

 

[imagineer]

I think the solution going forward, (cost, implementation time, maintenance, adjustability) will be cord reels suspended above.

 

[sparky 1971]

I am a fan of overhead cord reels. The problem is getting a good cord reel that will still retract without any help after a dozen uses. I have one customer where money isn't an issue, for them, I use Reelcraft reels, but those are expensive. In my own shop, I have three Flexzilla's, one 25' with 16/3 cord and two 50' with 14 gauge cord and I don't see any need for anything with 12 gauge. So far, so good with the Flexzillas, but I did mount them on the wall, high enough that they are out of the way, but low enough that I can reach them without a ladder to help the cord wind back up if the need ever arises. I haven't had problems yet, hopefully never will.

Reelcraft Cord Reels - Acme Tools

Shop Reelcraft electrical cord reels to get cords off your shop floor and keep them neatly organized. Buy Reelcraft electrical cord at acmetools.com. - Acme Tools

www.acmetools.com

https://www.menards.com/main/electrical/electrical-cords-surge-protectors/extension-cords/flexzilla-reg-50-14-3-3-outlet-retractable-extension-cord-reel/e8140503/p-60300229342-c-6410.htm?tid=-7756862145431106827&ipos=4

https://www.menards.com/main/electrical/electrical-cords-surge-protectors/extension-cords/flexzilla-reg-25-16-3-3-outlet-retractable-extension-cord-reel/fz8160253/p-60300229237-c-6410.htm?tid=4576379213655994902&ipos=5

 

[gahrajmahal]

Sorry to hear about your fall! Hope you weren’t hurt too bad.

I notice by your avitar (MG midget) you may enjoy a little electrical suffering. Having spent time around machine tools, a concrete trough to run electrical cables was a common practice and made access to them pretty easy but was often still a bit of a trip hazard, a place for a dropped item to fall into, or a place for water and oil to collect (think changing antifreeze).

Most other factories I worked in we placed power drops with disconnects down low. The drop consists of a steel box on the ceiling and a Kellum grip supporting the short extension cord that will hang down and not retract.

In my own gahraj, where you can also find an MGB in the summer, I ran an electrical box directly overhead of the passenger door side of one bay. This gets used often when I need a under hood light or to connect the battery charger. The ceiling is less than 9 feet high so I can reach it easily.

 

[Norcal]

For cord reels Appleton Reelite is damn nice, only problem is that you will **** yourself you when you see the price.

 

[imagineer]

Sorry to hear about your fall! Hope you weren’t hurt too bad.

Thanks. The cut was small, but deep. I came down on the front corner of the lower leg of a welding cart and ended up with a 2 sided, 90 degree, 1/2" long piercing in the meat of my (58 year-old) right deltoid. I'm sure it needed stitched, but I was too pissed about the fall and messing up the welder to care. It's healing, but hurts like hell.

 

[gahrajmahal]

Those are some cool welding carts

 

[RivennHewn]

Floor outlets end up being in the wrong place 2 months after installation. Go overhead.

Agreed

 

[imagineer]

Those are some cool welding carts

Thanks. FWIW, the leading edges of the extrusion holding the front casters have been rounded should I dive on one again.

 

[jeepxj]

for the welder circuits you can go low dollar with cable support grips.

https://www.amazon.com/dp/B002713C00/?tag=atomicindus08-20

or more expensive nicer looking ones.

3/4" NPT STEEL CORD GRIP (.500"-.625") WITH MESH

3/4" NPT STEEL CORD GRIP (.500"-.625") WITH MESH

www.elecdirect.com

 

[mbatarga]

It's a bit late for you - but I had a trench planned for my slab pour. It runs from the far right side in the picture to the middle third in my shop to provide power and dust collection piping to my table saw.

 

[Quick240]

It's a bit late for you - but I had a trench planned for my slab pour. It runs from the far right side in the picture to the middle third in my shop to provide power and dust collection piping to my table saw.

I like this. How deep and wide is the trench? And what are you using to cover it?

 

[jeepxj]

I like this. How deep and wide is the trench? And what are you using to cover it?

a 20' stick of C channel wouldn't be the end of the world in a shop. i like this idea.

 

[snackmix]

My old shop I had my table saw right over an expansion joint in the floor. It was built 30 years before I moved in, I used a screwdriver to dig all the crud out the joint and laid the extension cord in there and it worked great for the 4 years I was there

 

[mbatarga]

I like this. How deep and wide is the trench? And what are you using to cover it?

Sorry - just saw your question. The trench was planned early on to carry both power to the saw - as well as a 4" diameter dust collection pipe. The trench is about 10" wide and 6" deep - with a 3/4" ledge on both sides it's entire length. I've got 3/4" plywood sections each 4' long from the saw over to the wall - so I've got quick access and the cover is flush with the rest of the floor.

 

[mike93lx]

Sorry - just saw your question. The trench was planned early on to carry both power to the saw - as well as a 4" diameter dust collection pipe. The trench is about 10" wide and 6" deep - with a 3/4" ledge on both sides it's entire length. I've got 3/4" plywood sections each 4' long from the saw over to the wall - so I've got quick access and the cover is flush with the rest of the floor.

Nice

 

[roc_on_the_rocks]

Thanks. The cut was small, but deep. I came down on the front corner of the lower leg of a welding cart and ended up with a 2 sided, 90 degree, 1/2" long piercing in the meat of my (58 year-old) right deltoid. I'm sure it needed stitched, but I was too pissed about the fall and messing up the welder to care. It's healing, but hurts like hell.

Those are some sharp looking welding carts!

Sorry for your fall, these accidents ****, get well soon.

 

[tallhair]

It's a bit late for you - but I had a trench planned for my slab pour. It runs from the far right side in the picture to the middle third in my shop to provide power and dust collection piping to my table saw.

That trench looks really useful for your application. Very nice