Author Topic: HVAC cord and plug mods  (Read 8433 times)

Offline bonneyman

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HVAC cord and plug mods
« on: October 11, 2018, 03:06:03 PM »
I used to use corded drills when I started in AC. Then the first battery-powered drills came out, and I borrowed different brands from co-workers to see which one fit me best. It was the old Makita blue stick drills, 9.6 volts. Loved 'em!
After about 10 years the new batteries became metal hydride instead of Ni-Cads. They didn't last as long, and self-discharged way too fast. Eventually got tired of it, and wasn't going to re-invest in cordless drills (as I'd seen the writing on the wall with manufacturers "upgrading" every few years and you'd have to re-invest in the new voltage).
So I went back to a corded drill. I had a 12 foot cord installed on my Skill drill and just plugged into the roof recpt - had plenty of room to get all around most units. But there were times when a duplex recpt wasn't close by - and hauling out 100' of extension (or more) got old fast! Figured I'd patch together a plug so I could hook in my corded drill with the most common boxes I found on the roof. When a new recpt comes out - time to make another McGyver plug!

The first one is what's called a "widow-maker". So-called because when you're hooking into one leg of a standard AC disconnect box, and if you get it clipped in wrong - or just aren't paying attention to the bare connectors in there - your significant other is gonna be single! Mine is a store bought one I've had for years, but I'm sure some savvy old coot slapped one together out of scrap pieces and then companies saw how popular it was and started mass producing them.
Gotta be careful anyways, but especially so on 3 phase disconnects, as one of the legs is 'wild" (i.e. 220 volts not 110) so hooking between that leg and ground could blow your drill and/or kill you.
« Last Edit: October 11, 2018, 07:02:10 PM by bonneyman »

Offline bonneyman

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Re: HVAC cord and plug mods
« Reply #1 on: October 11, 2018, 03:09:50 PM »
Next is a "polarity reverser" I made to aid in troubleshooting.
Most modern furnaces use flame rectification to determine if the burner flame is one. The process only works if the polarity is correct. Alot of time installers will just wire up the furnace according to standard color wires without actually checking the polarity. System will work fine in summer, but the winter hits and the furnace will not light. This cord lets me switch the polarity as fast as plugging in a cord, instantly telling me if the no-start is a reversed polarity situation. (The wires in this mod cord are cross connected white to black - easy peasy). Great time saver.

Offline bonneyman

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Re: HVAC cord and plug mods
« Reply #2 on: October 11, 2018, 03:12:14 PM »
A straight-line cord with an added auto type fuse - say 10 or 15 amps. Plenty to run a drill or two, not too high to exceed the wire ampacity, but a safety if someones drives over an extension or drops something sharp and heavy and pinches the wires. Auto fuses are cheap, readily available, and can save a life.
« Last Edit: October 11, 2018, 03:27:41 PM by bonneyman »

Offline bonneyman

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Re: HVAC cord and plug mods
« Reply #3 on: October 11, 2018, 03:21:07 PM »
Next up is a cord for running a drill off of a evap cooler box. Locally our codes require wahts calle a Midwest box. It's a 3 way recpt box, fused, with different threaded fuse sockets so nobody can put a bigger fuse in the socket. Attempting to do so will strip out the socket threads and require a new box.
If I need a corded drill around a cooler, in times past I ran an extension cord. Figured there had to be a better  way, so I took an old male 4 prong plug and wired a female 3 prong to it in such a way that when the cooler switch was set to "high" it would feed 110 v to the female plug. Hook up your drill, and never have to stop!
Midwest boxes 3 sockets are motor high speed  (15A), motor low speed (12A) and water pump (1.25A). Obviously you can't tap into the pump recpt (even if your drill plug would fit) because most drills are 2A+, and you pop the fuse. So I wire my mod cord up to the motor high prong - gives me plenty to run my drill (plus 1 or 2 other things for co-workers) without overstressing the prongs, wiring, or downstairs switches - and we're still protected by the circuit breaker.

« Last Edit: October 11, 2018, 03:36:38 PM by bonneyman »

Offline bonneyman

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Re: HVAC cord and plug mods
« Reply #4 on: October 11, 2018, 03:26:44 PM »
Sometimes evap coolers are hard-wired into the structure. Not really code, but it is what it is. So there's no external box as above to plug into. My new mod cord will plug into the internal recpt box, which has an odd 5 female prong setup that most newer standard coolers use. (Can handle either 110 or 220 volts). I can unplug both internal plugs, have the owner turn on the evap switches downstairs, and I can thus get 110 volts - but the unit is completely safe.

Here's a spare dual recpt I have on the truck to replace any melted ones I find to show you the configuration. Top is 5 prong motor, bottom is pump (and - though it will physically accept the drill plug - I wouldn't plug it in there, as the normal current is only 1.25 amps and I don't know what the wiring/switches setup downstairs is).

Here's the completed cord. Looks really good - almost store bought!
« Last Edit: October 12, 2018, 03:57:29 PM by bonneyman »

Offline bonneyman

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Re: HVAC cord and plug mods
« Reply #5 on: October 11, 2018, 03:32:38 PM »
And a REALLY good idea is to check your output on you plugged in mod cord with one of the $6 polarity testers. Cheap insurance, available everywhere - and a double check on your rigged power setup.


Offline kwoswalt99

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Re: HVAC cord and plug mods
« Reply #6 on: October 11, 2018, 04:12:53 PM »
And a REALLY good idea is to check your output on you plugged in mod cord with one of the $6 polarity testers. Cheap insurance, available everywhere - and a double check on your rigged power setup.

I don’t understand, ac current has no polarity?

Offline bonneyman

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Re: HVAC cord and plug mods
« Reply #7 on: October 11, 2018, 04:50:27 PM »
And a REALLY good idea is to check your output on you plugged in mod cord with one of the $6 polarity testers. Cheap insurance, available everywhere - and a double check on your rigged power setup.

I don’t understand, ac current has no polarity?

They're called polarity testers, but all they're really doing is making sure the hot and neutrals are in the correct location. In the above situation I'm merely using it to determine if I have power and is the ground working properly. It's just alot handier for this than a multimeter.

Offline bonneyman

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Re: HVAC cord and plug mods
« Reply #8 on: October 11, 2018, 07:32:47 PM »
Here's a trio of little extras that I've found useful and along the lines of "plug-in" testers.
On the left is a yellow polarity tester made by GB. Around $6-8, seems like everybody makes them.
In the middle is a line splitter. Lets you check amp draw on 110 volt devices without having to tear open panels and get to innards. Just remove the device plug from the wall, plug this thing in, then plug the device into the other end. Now you can check the amps while the thing is running without trouble. Used to use it on refrigerators to see if the compressor was running without pulling the full fridge out from the wall. $18
On the right is an LED lighted plug I got from Ace. Good for plugging into lamps or other hard to see wall recpts. If a lamp is out - especially with the spiral florescent bulbs - one peek behind the couch tells you if the powers on (and it is the lamp thats bad) or if the CB is tripped. Saves alot of sore back muscles. $6
But I use it typically just to see if I've got power at a plug. I'm lazy!
« Last Edit: October 11, 2018, 07:40:46 PM by bonneyman »

Offline strik9

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Re: HVAC cord and plug mods
« Reply #9 on: October 11, 2018, 07:53:26 PM »
We only use two wire (hot and neutral) with no ground wire.  Those outlet testers are cool but outside of commercial and industrial buildings they are mostly just goung to tell you the obvious....

  There is no ground.   And probably the polarity is wrong.   

Offline J.A.F.E.

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Re: HVAC cord and plug mods
« Reply #10 on: October 11, 2018, 08:27:58 PM »
I use those little polarity testers a quite a bit.
People who confuse etymology and entomology bug me in ways I can’t put into words.

Offline bonneyman

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Re: HVAC cord and plug mods
« Reply #11 on: October 11, 2018, 10:01:52 PM »
I might sound like a broken record, but I almost felt like I had to come up with these kinds of things to save time. When working for a boss I was always getting more and more calls, and had to find ways to shave time on a job in the hopes of getting a little ahead on the day and not always being out till after sundown. Then when I started my own business coming up with labor or time saving ideas got me home before I was like totally dead.
And from what I've seen the past year in my industry the pressure has only increased!  :-\