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Old 12-06-2010, 01:58 AM   #1
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Exotic "Extension Cord" - 240v Service into 120v Outlets.. Will this work???


Hi guys -
I'm looking for a bit of electrical expertise.. I have a satellite breaker box panel in my yard being serviced by 100 Amps of 240 single phase (off of my main panel box).. circuit is a 240 line to my water shed (on 30A breakers) and the left over is to be shared between the inground pool stuff and exterior lighting... Neither of which am I using AT ALL. The only thing being used is the 240 extension to my water shed (running a 1.5 HP pressure pump for potable water service, intermittently) - and a couple of light bulbs (on VERY rare occasions).

My issue is this: Figuring I have 70 Amps of my satellite box available for use -- I need to run some heaters in my greenhouse (30x50) -- Which is about 30ft from the satellite box. I was going to "make" a real heavy duty extension cord - a "hard wired" one... I've tried this before with 10 Gage extension cords plugged into 20A GFI's @ the box location and MELTED the connections where the demand (heater) meets the female extension cord socket. Obviously the wire rated at 20 amps outlasted the "15 Amp connectors" on both ends. Combined with the resistance created by plug socket connections, it failed and over heated the connection socket on the demand end - but did NOT trip the 20A GFCI which the extension cord was plugged into or effect the "male" end. Go figure.

So I'm making my OWN extension cord & hard wiring it straight to the box. - "A SUPER DUTY ONE" & this time out of 6 Gage wire and socketed with 2- 20A (or 15's) GFCI's on each hot leg -- I'm wondering if I can use this 4-conductor wire and set it up this way....???

BTW - the NM-B is rated for indoor - so I'm stuffing it into 3/4" LiquidTite flexible PVC outdoor conduit (chem welded @ joints) and using PVC outdoor gasketed duplex boxes with rain covers.

I have attached a picture of the schematic.

Thanks in advance for your help...
Attached Files
File Type: doc schematic.doc (30.0 KB, 140 views)


Last edited by GreenHouser; 12-06-2010 at 03:46 PM. Reason: clarification
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Old 12-06-2010, 05:42 AM   #2
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Exotic "Extension Cord" - 240v Service into 120v Outlets.. Will this work???


Quote:
So I'm making my OWN extension cord - "A SUPER DUTY ONE" & this time out of 6 Gage wire and socketed with 2- 20 A GFCI's on each hot leg -- I'm wondering if I can use this 4-conductor wire and set it up this way....???
Ayuh,.... Sounds like a Bubblegum job...

Use a 240v Welder plug, 'n socket...

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Old 12-06-2010, 06:33 AM   #3
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Exotic "Extension Cord" - 240v Service into 120v Outlets.. Will this work???


Run Forrest, Run.
Why don't you do this right and trench a new line to the greenhouse and guit rigging stuff up that can cause fire, death and distruction!!!!!!!!!!!!
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Last edited by jbfan; 12-06-2010 at 10:45 AM. Reason: spelling
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Old 12-06-2010, 09:31 AM   #4
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Exotic "Extension Cord" - 240v Service into 120v Outlets.. Will this work???


You are flirting with danger... if you use 20A receptacles, the circuit must be protected at 20A. NM-B is not to be used in a wet location... outdoors in conduit is considered a wet location.

Follow the advice already given and put in a proper service to the greenhouse.
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Old 12-06-2010, 09:48 AM   #5
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Exotic "Extension Cord" - 240v Service into 120v Outlets.. Will this work???


Do yourself a favor and hire an electrician before you kill someone.

You mess with plumbing, you only get wet, you mess with electricity and someone always gets hurt.
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Old 12-06-2010, 09:53 AM   #6
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Exotic "Extension Cord" - 240v Service into 120v Outlets.. Will this work???




Very scary. Please listen to the advise given here.

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Old 12-06-2010, 11:50 AM   #7
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Exotic "Extension Cord" - 240v Service into 120v Outlets.. Will this work???


Okay - Thanks for all the comments - This is the DIY chatroom right?? Not the DDIY (Don't Do It Yourself) Chatroom??

I really didn't want to put my life story up here.. I have bent my share of conduit, swung a few hammers & flipped several REMOD jobs over the past 4 decades.. So PLEASE - SPARE ME THE OSHA CODE RANT!! This isn't my first rodeo.

To explain FURTHER -- NO, I can NOT put the conduit into the ground -- as my ground is SOLID limestone <2" below the grass line. So I am stuck laying the legs over ground during the scant 2 months of cold weather...

I only need the heat at night and only on the coldest nights.

I need to make a better extension cord to easily handle 30A @ 100'. I selected the 6/3 NM-B because of the 4 wire wrap. I felt that "hard-wiring" it into the box would reduce the voltage drop caused by the duplex connection. Since I was using liquidtight PVC conduit - I thought that would be suitable for using indoor Romex outdoors, temporarily. -- I can EASILY swap the indoor 6/3 for outdoor 6/3... Again -- this is just a 2 month BAND-AID, nothing more.. Next year, I will have propane infra red and will not need the "cord".

MY QUESTION WAS --- IS THE WIRING SCHEMATIC ACCURATE? Can a 4 wire 240v line be adulterated to supply 2 circuits of 120v @ 30A??.. I really don't want to run 4 separate 15A circuits @ 100', into the greenhouse.. Especially for a 2 month "patch" job...

Is there a BONIFIED electrician in the house??...
PLS view attached scematic..

Thanks again!!
Attached Files
File Type: doc schematic.doc (30.0 KB, 71 views)

Last edited by GreenHouser; 12-06-2010 at 12:26 PM.
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Old 12-06-2010, 12:03 PM   #8
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Exotic "Extension Cord" - 240v Service into 120v Outlets.. Will this work???


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Originally Posted by GreenHouser View Post
I've tried this before with 10 Gage extension cords and MELTED the connections where the demand (heater) meets the female extension cord socket. Obviously the wire rated at 30 amps outlasted the "15 Amp connectors". Combined with the resistance created by plug socket connections, it just over heated the connection sockets - but did NOT trip the 20A GFCI which the extension cord was plugged into. Go figure.
Why would you expect the GFCI to trip? You didn't have a ground fault you only had a fire hazard?
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Old 12-06-2010, 12:45 PM   #9
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Exotic "Extension Cord" - 240v Service into 120v Outlets.. Will this work???


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Originally Posted by a7ecorsair View Post
Why would you expect the GFCI to trip? You didn't have a ground fault you only had a fire hazard?


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Old 12-06-2010, 01:05 PM   #10
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Exotic "Extension Cord" - 240v Service into 120v Outlets.. Will this work???


Quote:
Originally Posted by GreenHouser View Post
Okay - Thanks for all the comments - This is the DIY chatroom right?? Not the DDIY (Don't Do It Yourself) Chatroom??

I really didn't want to put my life story up here.. I have bent my share of conduit, swung a few hammers & flipped several REMOD jobs over the past 4 decades.. So PLEASE - SPARE ME THE OSHA CODE RANT!! This isn't my first rodeo.


Is there a BONIFIED electrician in the house??...
PLS view attached scematic..
Your attitude may lose you the answers you seek here. Please bear in mind you are in a DIY PUBLIC forum and when you post questions here, you must be open to answers/comments from.... well, basically anyone in the world!
In the Electrical Forum Section here, our regulars are mainly concerned with safety overall, as we have many posters who should never pick up a screwdriver attempting things way over their heads and dangerous. Please excuse any perceived insults, I'm sure the guys here were just looking out for you, since you have such a hazardous situation going on there.

DM
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Old 12-06-2010, 01:39 PM   #11
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Exotic "Extension Cord" - 240v Service into 120v Outlets.. Will this work???


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Originally Posted by a7ecorsair View Post
Why would you expect the GFCI to trip? You didn't have a ground fault you only had a fire hazzard?
I used a HD 20A 10 Gauge silicone extension cord bought from Home Depot under the "Rigid" label... It has a tiny light embedded into the clear socket end. I originally thought that the cord light failed and caused a short that melted (fused) the plug to the socket. I figured that it was probably made in China - and well -- you get the drift. When the second cord failed - I knew I was drawing too many amps, but i still thought the lighted end had something to do with it still.. These are supposed to be real good cords! (@$100+ ea. they ought to be!).. I was only drawing 15A through the cord plugged into a 20A GFCI. The cord is rated for 20A (10g Rigid) -- It never occurred to me that the plug ends would only be rated for 15A - and furthermore the voltage drop from 2 connection points, not to mention the 100 ft run length. That may have been a poor choice on my part... That's why I'm trying to do a better job this time.


I'm just trying to manufacture a better version of an extension cord - An "Industrial grade" one so to speak.. Custom socketed with GFCI's (instead of just plug outlets). I only have a demand of 15 Amps @each duplex (2 heaters on each GFI) - I think I selected the 20A GFI's by mistake -- I think I should use 15A rated ones to better match the heaters draw?? -- Before I buy all the parts -- I want to make sure it will work overall -- RELIABLY & SAFELY. It's me & my wife here -- no kids/animals/visitors/etc. I am the ONLY one who deals with the greenhouse. I'm on a "Mini-Ranch" type property 20 ac.. - So the "risk" is all mine (no stray kids to stumble into it).. So as long as I follow the safety rules (as it applies to watering) - I will survive to the spring!! lol The plants in this house are mostly succulent cactus and plumeria.. They do not require heavy (constant) watering through the winter months as they are effectively dormant.. Watering is once a week, if that. Humidity will be lower as well @ +/- 50-70%...

These heaters BTW -- are the "electric radiator" versions (liquid filled). They offer 3 levels of use ---> 600w, 900w, and 1500w - and are thermostatically controlled. I use them on the 900 watt setting - ONLY. And clearly -- I don't water the greenhouse (or expect to) while the power is on, and radiators uncovered. Furthermore -- the outlets are tucked away & protected with covers to prevent "drip-in's".. I "spot-water" anyways - by hand.. I do not do unattended broadcast watering.

This is NOT for a permanent installation... This is ONLY for the next 2 - 2.5 months, but I do want to make it as safe & reliable as possible. This greenhouse does NOT have to be heated to 80+ degrees.. It only needs to buffer up and keep the overnight temps above 50F... I'm in central Texas - nights rarely drop below 30 during the coldest times. By February - I only need half as many heaters - and only intermittently. By March -- they are gone altogether and cord is removed...


Next year - I'm getting a propane fired infra red tube system. Problem solved.

My need is to get through this winter only.

Thanks again!

Last edited by GreenHouser; 12-06-2010 at 02:59 PM.
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Old 12-06-2010, 01:58 PM   #12
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Exotic "Extension Cord" - 240v Service into 120v Outlets.. Will this work???


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Your attitude may lose you the answers you seek here. Please bear in mind you are in a DIY PUBLIC forum and when you post questions here, you must be open to answers/comments from.... well, basically anyone in the world!
In the Electrical Forum Section here, our regulars are mainly concerned with safety overall, as we have many posters who should never pick up a screwdriver attempting things way over their heads and dangerous. Please excuse any perceived insults, I'm sure the guys here were just looking out for you, since you have such a hazardous situation going on there.

DM
I'm good with that -- No worries, I understand. I'm not a "first time" homeowner by a long shot. I've been taking things apart and rebuilding them all my life, & have more tools than any 3 ppl should possess (so my wife says!).. (lol) But how do you lead with that?? No one bothered to ask if I had the engineering skills to pull this off correctly. I do - no problem. I just want to do it properly and I'm not ashamed to ask a pro FIRST before I do something as dangerous as this. I meant no insult with the "OSHA" statement either - they are there for a good reason.. But it was short & to the point, without being outwardly brash.. Sorry if it seemed rude - that was not my intention.

BTW Dangermouse -- Are you an electrician/engineer/contractor?

Thanks again!

Last edited by GreenHouser; 12-06-2010 at 02:08 PM.
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Old 12-06-2010, 03:11 PM   #13
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Exotic "Extension Cord" - 240v Service into 120v Outlets.. Will this work???


None of the above.... I'm just a schlub that lives in the woods here in BFE..... LOL

I DID, however, build this home from the dirt to the shingles, including all of the electric, plumbing, framing, floors, etc. etc. etc. All permitted and passed. .... so far..... much of it was completed with the help of the wonderful regulars here, and not-so-regulars too. I still have a few more hoops to jump through, but I'm almost done with everything needing inspecting.

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Old 12-06-2010, 03:59 PM   #14
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None of the above.... I'm just a schlub that lives in the woods here in BFE..... LOL

DM
So BFE is @ ~3k feet over the Battle Creek International Airport??

Last edited by GreenHouser; 12-06-2010 at 04:05 PM.
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Old 12-06-2010, 05:19 PM   #15
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yup... I just keep going round... and round... and round...
I may land some day.

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