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Author Topic: Simple 120/240 power distribution cord  (Read 1948 times)

Offline Saccharomyces

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Simple 120/240 power distribution cord
« on: November 13, 2020, 01:32:03 pm »
Below, is version 2 of a simple power distribution scheme that I developed in my last brewery after I had 4-wire NEMA 14-30 service installed in my garage. 



In version 1, I used 12/4 SJOOW power cord, which limited me to a total of 20A of combined 120/240 service.   This time I used 10/4 SJOOW power cord and wired the inside pigtails from the receptacles using solid wire I stripped out of 10/3 Romex.  First off, It is clear to me that doing this kind of thing with 10-guage wire is fairly uncommon.  The difference in difficulty of build between 10-gauge and 12-gauge wire feels like an order of magnitude.  Ten-gauge is both large in diameter and very stiff.  Wire nuts are not designed for working with 30A wire.  Even the large red wire nuts are too small.  I tried using the blue Ideal in-sure push-in wire connectors.  They are very nice, but I was unable to insert SJOOW power cord 10-gauge stranded wire into these cool little devices.  I was about to give up and fall back to using 12-gauge wire when I found something even cooler than the Ideal in-sure connector.  They are made by a company called Wago.  The part number for the connectors I used is 221-613 (https://www.amazon.com/gp/product/B085ZQKQD2/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1).  These lever nuts are not cheap, but they are the only game in town when joining 10 gauge solid and stranded wire.

Anyway, the combination receptacle that I employed in the design is usually used to provide a light switch and a receptacle in one duplex package.  However, if one breaks the tab that joins the hot input terminals on the toggle switch and receptacle, connects the hot (black) wire to the hot input terminal of the toggle switch and then connects the hot output terminal of the toggle switch to the hot input terminal of the receptacle, it gives one a toggle switch controlled receptacle that can be used to turn a pump on and off.  The other side of the distribution box is a NEMA 6-20R receptacle that can power 20 amp 240 devices.


« Last Edit: November 13, 2020, 01:34:26 pm by Saccharomyces »

Offline Wilbur

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Re: Simple 120/240 power distribution cord
« Reply #1 on: November 13, 2020, 03:53:17 pm »
I hate the standard wire nuts, they're terrible with strand wire unless you tin the ends first.

Looks good! Any specific reason you didn't hard wire it in? I keep meaning to add a switched outlet to run my dehydrator and keg washer, I might finally have to get that done.

Are you going 1V or 3?

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Offline Oiscout

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Re: Simple 120/240 power distribution cord
« Reply #2 on: November 13, 2020, 10:28:43 pm »
When working with #10 AWG solid it's best to twist your wires together with a pair of linesman pliers and then spin the wire nuts on. ( Any size of solid wire IMO)

But you'll be hard pressed to find a receptacle or switch that takes a solid #10 easily. It wouldn't have have hurt to use #10 stranded either for your pig tail may have made life easier on you.

 I would suggest for ease of use and install when you build another device like this  use a 4 square box extension. Those industrial covers are a pain in the ASS!

Looks good though

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Offline Oiscout

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Re: Simple 120/240 power distribution cord
« Reply #3 on: November 13, 2020, 10:30:14 pm »
If you twist your wires together before you put your wire nuts on them either stranded or solid it makes a world of difference. And the wire nuts do what they are supposed to do

Also when dealing with splicing stranded and solid together lead your stranded ahead of the solid wire when you twist the nut on, works every time

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« Last Edit: November 13, 2020, 10:31:46 pm by Oiscout »

Offline goose

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Re: Simple 120/240 power distribution cord
« Reply #4 on: November 14, 2020, 07:53:42 am »

But you'll be hard pressed to find a receptacle or switch that takes a solid #10 easily. It wouldn't have have hurt to use #10 stranded either for your pig tail may have made life easier on you.

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I have never seen a switch or a 120V receptacle that would accept #10 wire and am not sure such beasts exist.  The reason for this is that most receptacles and switches are meant to be used in 120 VAC circuits and are not designed to handle 30 amps, which is the current rating for #10 wire.  They are either for #14 (15 A) or #12 (20 A) for safety reasons.  Thr current rating of these devices are well marked on the device and on he package.  I am pretty sure that if someone tried to use a light switch or a duplex receptacle in a 30 amp circuit the current draw could very well melt the contacts in these devices.
I am not trying to be an alarmist here.  Although you are probably OK current wise on the 120VAC side of the circuit for what you are using it for, it is never a good idea to put a lower currrent rated device in a higher current source without using a properly rated circuit breaker to prevent excessive current draw in the circuit. This could possibly cause overheating in the wire and/or device leading to a potential fire hazard.  This is why your house has circuit breakers rated for for the wiring circuit in your distribution panel.  I am guessing that the 120VAC side is going to be used to run something like a pump.  However, if the pump fails, overheats, and shorts out you could be drawing more current than the switch/receptacle device can handle before the breaker in your panel trips.  Just be careful here.  It would be a good idea in the next version to include something like a circuit breaker or a GFCI breaker to protect the 120VAC side.  You can find a push button breaker at Grainger that would mount with a small circular hole in your distribution box.

https://www.grainger.com/search?searchQuery=push+button+circuit+breaker&searchBar=true

You are OK on the 240VAC side since the breaker that is installed in your panel will protect that side of the circuit
« Last Edit: November 14, 2020, 08:00:01 am by goose »
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Offline Saccharomyces

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Re: Simple 120/240 power distribution cord
« Reply #5 on: November 14, 2020, 07:56:46 am »
When working with #10 AWG solid it's best to twist your wires together with a pair of linesman pliers and then spin the wire nuts on. ( Any size of solid wire IMO)

But you'll be hard pressed to find a receptacle or switch that takes a solid #10 easily. It wouldn't have have hurt to use #10 stranded either for your pig tail may have made life easier on you.

 I would suggest for ease of use and install when you build another device like this  use a 4 square box extension. Those industrial covers are a pain in the ASS!

Looks good though

The problem I encountered when attempting to use wire nuts was that even the largest size I could find could not handle two solid and one stranded 10 gauge wires in a pig tail.  I have not doubt that a skilled electrician can do it, but even the large red nuts were only good for two wires.  Installing this 14-30 circuit and building this box is the first time I have worked with 10 gauge wire, so there were a lot of lessons learned. The 14/2 and 12/2 work I did on homes I previously owned was nothing like running this circuit.  I can only imagine what it is like to run 6/3 Romex for a NEMA 14-50.  If I had to do it over, I would have pulled 12/3 for a 4-wire NEMA 14-20 120/240 circuit or 12/2 for NEMA 6-20 circuit and used the existing 120V circuit in my garage.  Twenty amp 240 service is so much more sane than 30 amp 240 service.   A NEMA 6-20R 240 20A receptacle is the same size as a NEMA 5-15R 120 15A receptacle whereas a NEMA 14-30R receptacle is a two-gang box affair.

By the way, I used a deep drawn 4" square box.  I used a regular depth 4" square box on my last build.  That extra 5/8ths of an inch of depth makes a difference.  I agree with you on the industrial cover.  However, that is the only place where there is a ground connection on the entire box.  I used the center screw on the duplex receptacle to ground the box.
« Last Edit: November 14, 2020, 08:21:56 am by Saccharomyces »

Offline Oiscout

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Re: Simple 120/240 power distribution cord
« Reply #6 on: November 14, 2020, 08:01:05 am »
You can totally use a box extension on a deep too!



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Offline Oiscout

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Re: Simple 120/240 power distribution cord
« Reply #7 on: November 14, 2020, 08:06:16 am »

But you'll be hard pressed to find a receptacle or switch that takes a solid #10 easily. It wouldn't have have hurt to use #10 stranded either for your pig tail may have made life easier on you.

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I have never seen a switch or a 120V receptacle that would accept #10 wire and am not sure such beasts exist.  The reason for this is that most receptacles and switches are meant to be used in 120 VAC circuits and are not designed to handle 30 amps, which is the current rating for #10 wire.  They are either for #14 (15 A) or #12 (20 A) for safety reasons.  Thr current rating of these devices are well marked on the device and on he package.  I am pretty sure that if someone tried to use a light switch or a duplex receptacle in a 30 amp circuit the current draw could very well melt the contacts in these devices.
I am not trying to be an alarmist here.  Although you are probably OK current wise on the 120VAC side of the circuit for what you are using it for, it is never a good idea to put a lower currrent rated device in a higher current source without using a properly rated circuit breaker to prevent excessive current draw in the circuit. This could possibly cause overheating in the wire and/or device leading to a potential fire hazard.  This is why your house has circuit breakers rated for for the wiring circuit in your distribution panel.  I am guessing that the 120VAC side is going to be used to run something like a pump.  However, if the pump fails, overheats, and shorts out you could be drawing more current than the switch/receptacle device can handle before the breaker in your panel trips.  Just be careful here.  It would be a good idea in the next version to include something like a circuit breaker or a GFCI breaker to protect the 120VAC side.  You can find a push button breaker at Grainger that would mount with a small circular hole in your distribution box.

https://www.grainger.com/search?searchQuery=push+button+circuit+breaker&searchBar=true

You are OK on the 240VAC side since the breaker that is installed in your panel will protect that side of the circuit
Single pole switches and single receptacles used in different applications such as a disconnecting means for roof top air handler units and exhaust fans and used in certain data center applications such as Server racks etc do exist but are not common. The every day residential electrician would really have no need to use them

I just finished a roof top unit job that had all the above.

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Offline Oiscout

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Re: Simple 120/240 power distribution cord
« Reply #8 on: November 14, 2020, 08:15:14 am »
Depending on the insulation and length you can find certain #12 AWG that is rated for 30 amps.

Ambient temperature application and insulation all have a factor in determining ampacity.

Electricity isn't as cut and dry as people think.

That 120 volt part of the circuit will only "draw" as much amperage as it needs to the do the work you set it out to do. Having it hooked to a 30 amp Over current protection device won't send 30 amps to that receptacle but will only trip when 80 percent of the protected load is reached in a over current situation.

The receptacle being rated for 20 Amps is less of an issue than how you terminated said wires on the receptacle. Did you back stab or did you side saddle wire. Depending on the UL listing of the termination points that is where the danger comes in. Receptacles and switches just be terminated based on the reccomended method that UL labs have outlined for it



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Offline Saccharomyces

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Re: Simple 120/240 power distribution cord
« Reply #9 on: November 14, 2020, 08:20:13 am »
I have never seen a switch or a 120V receptacle that would accept #10 wire and am not sure such beasts do not exist.  The reason for this is that most receptacles and switches are meant to be used in 120 VAC circuits and are not designed to handle 30 amps, which is the current rating for #10 wire.  They are either for #14 (15 A) or #12 (20 A) for safety reasons.  Thr current rating of these devices are well marked on the device and on he package.  I am pretty sure that if someone tried to use a light switch or a duplex receptacle in a 30 amp circuit the current draw could very well melt the contacts in these devices.

...

You are OK on the 240VAC side since the breaker that is installed in your panel will protect that side of the circuit

I was aware of that problem when I built the box.  The 240V circuit I ran to my garage meets code.  From my understanding, code does not cover anything  that is plugged into a receptacle; otherwise, 15A appliances could not be plugged into a 20A kitchen circuit.   The reason why I refer to it as a "simple power distribution cord" is because it is not fuse or breaker protected.  Compromises had to be made.  Do I use a 14-gauge pigtail to the NEMA 5-15 duplex receptacle and risk the wire getting smoked on a dead short? Or do I wire the receptacle with 10-gauge pigtail and risk the NEMA 5-15 receptacle and switch getting smoked?  Neither outcome is desired.   What I am hoping is that on a dead-short the power cord for the device smokes first.  A full-blown power distribution panel would have the 5-15 receptacle and switch protected by a 15A single-pole breaker and the 6-20 circuit protected by a 20A double-pole breaker.  However, it would no longer be in a convenient form.  Trust me, I looked for slo-blow inline fuses that could handle 15A and 20A respectively that would have fit in the box.

By the way, one can get 10-gauge wire to fit 5-15 and 6-20 terminals, but there is not much room for error.  The loop has to be made just large enough to fit over the screw.
« Last Edit: November 14, 2020, 09:01:51 am by Saccharomyces »

Offline Saccharomyces

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Re: Simple 120/240 power distribution cord
« Reply #10 on: November 14, 2020, 09:24:31 am »
I hate the standard wire nuts, they're terrible with strand wire unless you tin the ends first.

Looks good! Any specific reason you didn't hard wire it in? I keep meaning to add a switched outlet to run my dehydrator and keg washer, I might finally have to get that done.

Are you going 1V or 3?

I am not doing the traditional electric brewery with immersed element thing.  I prefer to use a Mai Cook 3500W portable induction cooktop, so that I can use an immersion chiller (having a cord allows me to move the cooktop toward the front of my garage when boiling and move it to the back for chilling using a utility sink).  I was was probably the first amateur brewer to take a chance on the Mai Cook cooktop when I pulled the trigger on the purchase in early 2016.  The manufacturer was selling direct from China at that point in time and the unit shipped with a Chinese plug.  I was unfamiliar with the Chinese wiring color code for 240V, so I worked with one of their engineers to change the plug to a NEMA 6-20P plug.  I am the person who convinced this manufacturer to switch over to shipping the unit to North America with a 6-20P plug.  If anyone manages to get a pre-NEMA 6-20P version of this stove, the green-yellow wire is protective ground and the brown and blue wires are the 240V hots (black and red 240V wires in North American terms).  The same color code is used for 120V devices, but the blue wire is neutral (white wire in 120V terms) instead of being a hot.  The brown wire is hot (black wire in a 120V terms).

Offline Oiscout

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Re: Simple 120/240 power distribution cord
« Reply #11 on: November 14, 2020, 01:36:45 pm »
I hate the standard wire nuts, they're terrible with strand wire unless you tin the ends first.

Looks good! Any specific reason you didn't hard wire it in? I keep meaning to add a switched outlet to run my dehydrator and keg washer, I might finally have to get that done.

Are you going 1V or 3?

I am not doing the traditional electric brewery with immersed element thing.  I prefer to use a Mai Cook 3500W portable induction cooktop, so that I can use an immersion chiller (having a cord allows me to move the cooktop toward the front of my garage when boiling and move it to the back for chilling using a utility sink).  I was was probably the first amateur brewer to take a chance on the Mai Cook cooktop when I pulled the trigger on the purchase in early 2016.  The manufacturer was selling direct from China at that point in time and the unit shipped with a Chinese plug.  I was unfamiliar with the Chinese wiring color code for 240V, so I worked with one of their engineers to change the plug to a NEMA 6-20P plug.  I am the person who convinced this manufacturer to switch over to shipping the unit to North America with a 6-20P plug.  If anyone manages to get a pre-NEMA 6-20P version of this stove, the green-yellow wire is protective ground and the brown and blue wires are the 240V hots (black and red 240V wires in North American terms).  The same color code is used for 120V devices, but the blue wire is neutral (white wire in 120V terms) instead of being a hot.  The brown wire is hot (black wire in a 120V terms).
Are you running a pump off that 20 amp receptacle??

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Offline Saccharomyces

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Re: Simple 120/240 power distribution cord
« Reply #12 on: November 14, 2020, 03:45:26 pm »
I hate the standard wire nuts, they're terrible with strand wire unless you tin the ends first.

Looks good! Any specific reason you didn't hard wire it in? I keep meaning to add a switched outlet to run my dehydrator and keg washer, I might finally have to get that done.

Are you going 1V or 3?

The duplex combination 5-15 receptacle is for a pump.  That is why I rewired the toggle switch to control the socket. The 6-20R receptacle is for the 3500W induction cooktop.   The reality is that I could have run this setup on a 14-20 circuit made things easier for myself.  The induction stove and the pump together only draw 16A and that is with the cooktop on its highest setting.  The pump is never running when the cooktop is on its highest setting.

I am not doing the traditional electric brewery with immersed element thing.  I prefer to use a Mai Cook 3500W portable induction cooktop, so that I can use an immersion chiller (having a cord allows me to move the cooktop toward the front of my garage when boiling and move it to the back for chilling using a utility sink).  I was was probably the first amateur brewer to take a chance on the Mai Cook cooktop when I pulled the trigger on the purchase in early 2016.  The manufacturer was selling direct from China at that point in time and the unit shipped with a Chinese plug.  I was unfamiliar with the Chinese wiring color code for 240V, so I worked with one of their engineers to change the plug to a NEMA 6-20P plug.  I am the person who convinced this manufacturer to switch over to shipping the unit to North America with a 6-20P plug.  If anyone manages to get a pre-NEMA 6-20P version of this stove, the green-yellow wire is protective ground and the brown and blue wires are the 240V hots (black and red 240V wires in North American terms).  The same color code is used for 120V devices, but the blue wire is neutral (white wire in 120V terms) instead of being a hot.  The brown wire is hot (black wire in a 120V terms).
Are you running a pump off that 20 amp receptacle??

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Offline Oiscout

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Re: Simple 120/240 power distribution cord
« Reply #13 on: November 14, 2020, 03:49:41 pm »
I would have ran a 30 amp for it anyway to cover start up current. Right on keep on brewing brother!

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Offline Saccharomyces

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Re: Simple 120/240 power distribution cord
« Reply #14 on: November 15, 2020, 06:35:47 am »
Inrush current is what separates induction cooking from purely resistive cooking as is found in traditional electric cooking with an immersed element.