Extension cord wiring - 4 wires for two 110V circuits? 3

[BridgeSmith]

Please forgive me if my terminology is off a bit. I have a cable approximately 120' long, composed of 4 wires that are stranded wire of either 8 or 10 gauge, which I would like to set up to carry 2 household 110V AC circuits. For reference, it has black, red, white and green, in a rubber outer sheath, similar to a typical extension cord.

Question 1) If they're not labeled, how do I determine the gauge of the wire? It probably won't matter, since I only plan on 20A circuits, but I'd like to know what I'm dealing with.

Question 2) Is there an acceptable way to connect this? I was thinking of two options:

Option A:
Black - Hot #1
Red - Hot #2
White - Neutral #1 & Frame ground #2
Green - Neutral #2 & Frame ground #1

Option B:
Black - Hot #1
Red - Hot #2
White - Neutrals #1 & #2
Green - Frame grounds #1 & #2

Will one of these 2 ways work, is there a better way, or should it not be done?

 

[waross]

You must be living in an interesting time warp.
110 Volts was phased out over 50 years ago.
The first option is definitely not code compliant.
If you can not find markings on the cable, it may be past the end of its safe life span.
It is not safe to guess at wire gauge for the purpose of determining ampacity.
Option B is not normally acceptable for a 120 Volt (or 110 Volt) circuit. The neutral may be overloaded.
There is may be an exception if the conductors are 100% oversized for voltage drop,
The green must be used for grounding only, but may be used to ground more than one circuit.
1. Will one of these two ways work? Work or be safe and be code compliant?
Option A, not code compliant.
Option B, possibly but not enough information to say for sure.
2. Is there a better way?
Yes. A three wire or split circuit. Instead of using 120 Volts use 120/240 Volts with a shared neutral.
Talk to an electrician. We don't have enough information to say for sure.
3. Should it not be done? Probably not. If the cable marking are no longer visible, (It is a code requirement that a new cable be marked.) the cable is old enough that the integrity of the cable may be in doubt. Old rubber and plastic develops cracks, and may not be safe to use.
More information that may help;
Are you going to use plug connections or wire this in permanently?
Will you feed this directly from a breaker panel? Pictures?
What are your loads?


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[BridgeSmith]

My plan was to wire in 2 male, 3 prong plugs at the head, to be fed by separate extension cords from different outlets on different circuits. Then I would have 2 duplex outlets at the tail end, each fed by a separate 20A line. Essentially replacing 2 extension cords. It would be for temporary use for an outdoor PA/sound system plus a keyboard, wireless microphone receivers, CD player, etc.

I haven't stripped back the outer insulation yet, so I don't know if the wires are marked. I was hoping that if they weren't marked, the diameter of the stranded copper would tell me the gauge.

So I'd need to go with Option B and the neutral would need to be capable of carrying 40A, correct?

 

[waross]

Scary. I suggest use the green, the white and the black for one extension cord. Buy another cord for the other circuit.
Still concerns with the age of the cable.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[waross]

PS; If this is for a public event, you may be safer to buy two new cords. Liability and all that.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[bacon4life]

In additions to the concerns Bill outlined, some sound engineers are pretty adamant about avoiding mixing power supply circuits in order to avoid ground loop issues.

Although you state an intention to plug the cord into two different circuits, creating this type of unique cord makes a situation where it would be easy to insert both male plugs into the same supply circuit.

 

[BridgeSmith]

This is my cord, which I would use mostly for myself, but also considering for use at a church function at my church, where I would be running it to a sound system I would be setting up and operating. My understanding of ground loop issues is that if the circuits have a common ground those issues should be mitigated.

 

[BridgeSmith]

If the plugs were connected to the same circuit, that shouldn't be a problem, would it? The circuit would be protected at 20A, but the cords would have a greater capacity. It would just make the larger cord unnecessary.

 

[jraef]

There will be no markings on the inner wires, all markings would be on the outer jacket. Sometimes the ratings are molded into the rubber or plastic, not printed. Listed cord is required to be marked every 3 ft. If it is not listed then you have no idea of what you have. Luck is not a valid safety strategy.

Your options are not going to be compliant to any codes no matter how you do it, but what you could do more effectively that is close is to create what’s called an MWBC (Multi Wire Branch Circuit) in which two hot lines share a single neutral. Do NOT mix your grounds and neutrals. Despite them appearing to be common, they are NOT. The neutral is a “current carrying conductor”, ground is NOT, it is there for safety and, in your case, safely removing as much common mode (meaning referenced to ground) electrical noise. Sharing a neutral as an MWBC is far safer than mixing grounds and neutrals.

MWBCs come with other code requirements that you likely cannot meet because you will not have control of which circuits you tap off of when you use it, but as I said, if you insist on pursuing this folly, do so as close to “compliant” as possible.

And rather than making a two headed snake, terminate your cable into a 4” square steel box and install two separate single outlets (receptacles) side by side with steel covers, each fed with separate hots but both connected to the same neutrals, then ground everything.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[BridgeSmith]

"...rather than making a two headed snake, terminate your cable into a 4” square steel box and install two separate single outlets (receptacles) side by side with steel covers, each fed with separate hots but both connected to the same neutrals, then ground everything."

That was my plan. Actually, I already have that, other than the 2 receptacles are fed by the same plug right now. I plan on using a steel box for the 2 male plugs in place of the one extension cord plug it has now.

I will take a look at the outer jacket again. I think I remember something molded in to it.

Will it make any difference if the 2 circuits that feed it are from separate 120V main lines or the same one from the service panel?

 

[bacon4life]

How many amps of load will you have? If you have less 15 amps, just use a single circuit. Be aware that the standard outlet is rated 15 amps. If you have more than load than can be supplied by a single circuit, it would be imperative for load to be split between 2 circuits. With more than 20 amps and you connected both plugs to the same branch circuit, the best case would be the breaker trips on overload (and brings the event to a halt). The worst case is a fire. Although breakers are designed to trip on overloads, they do not eliminate the risk of catastrophic fire from overloaded wires.

 

[BridgeSmith]

I anticipate the sum of the loading being more than 20 amps, thus my reason for wanting to provide 2 circuits fed from separate breakers. I understand the size of the wires (the neutral in particular) will have to be adequate for sum of the protected capacities (2 - 20A circuits = 40A minimum capacity of each wire in the cord).

Thank you all for your help. Let me assure everyone, if I can't find the gauge of the wires marked on the cord, or if the gauge of the wires isn't adequate, I won't go forward with it. Same if I find any defects in the insulation. I have no desire to ruin my cord or start my church on fire. And yes, I do know that the current capacity of stranded wire is less than solid wire of the same gauge.

 

[jraef]

You don’t have to assure us, we are not the ones who will have to fight an inspector, or the fire...


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[xnuke]

...or with the insurance company after the fire who won't cover the damages because the installation didn't comply with the electrical code in effect when it was built.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[BrianPetersen]

Don't do this. Buy the right (separate) cables for each separate circuit and leave that cable on the shelf for some other time.

That cable may have been meant for a 3-way-switch circuit for a household lamp. (Incoming black "hot", switch #1 selects between connecting that between black and red in the cable that goes between the two switches, switch #2 selects between connecting those and an outgoing black "hot" to the bulb, white common and unsheathed ground pass straight through all the boxes without any switching - obviously the ground is tied to the ground screw at each box)

In that application only either one of the red or black "hot" wires carries the load but never both.

 

[BridgeSmith]

BrianPeterson, it's just a four-conductor extension cord. There are no switches, no intermediate boxes, and no connections except what I will make at the ends.

 

[crshears]

Even so, don't do it; go with the proper separate cords. That type of cord is for use with either a four-prong 120V/240V plug & receptacle with two "hots" 180° out of phase with each other, a neutral, and a ground, or possibly a 120/208V three-phase supply and ground conductor; don't succumb to the temptation to misuse it for other than its intended purposes, as much grief may befall you otherwise.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[BridgeSmith]

Reading up on multi-wire branch circuits, which seems to be essentially what I was trying to accomplish, both circuits must be connected to the same double pole breaker. Since I have no way of providing that, I will just keep it as is with one circuit until I, or a friend, has a use for it as a 240V supply. Thanks everyone for your help and advice.