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Old 05-28-2012, 09:34 PM   #1
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Best way to add one more wire to an existing conduit


I have a 1/2" EMT conduit that runs from the panel to a junction box about 80 feet away, then from there another run of 45 feet to the water heater.

The water heater is a 120V tankless. It was installed by the previous owner and cannot handle the demand. I need to put in a 50G tank heater but I need 220V.

It was obvious to me there used to be a tanked heater there, but along the way it was changed out, what I don't understand is what happened to the 220V wiring. Unless they kept one wire and re-purposed the other? No idea.

But now, I have a problem because it looks like I need to feed one more wire through this run.

This 1/2" EMT run is 80 feet long going through block walls, sections of inaccessible attic etc...and it already has 8 wires (5 hot 3 neutral) in them, all solid #12 copper wires and with solid wires how they tend to tangle up with each other around elbows, I have a hard time seeing how I can feed one more wire through. I tried to force a 100' fish tape forward and had a real hard time and it stuck after 20 feet.

What is the chance of me disconnecting ONE wire from the panel end, and tie two new wires to that, and pull that wire through from the other end and hope it will work? But I run the risk of messing up one wire if that one gets stuck in the middle too.

Any thoughts?

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Old 05-28-2012, 09:42 PM   #2
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Best way to add one more wire to an existing conduit


I commonly use an existing wire to pull in new wires---strip back about 4 or 5 inches of insulation on all wires to keep the diameter to a minimum--Use electrical tape to keep the splice together--

Get a bottle of 'slime' to lubricate the wires--

Use a helper so the wires remain tight and neat.

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Old 05-28-2012, 09:43 PM   #3
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Best way to add one more wire to an existing conduit


How are you figuring to pull in ONE wire to feed a 50G water heater? Isn't the heater 4500 watts? If so then #12 is NOT going to work. You need two #10's. You would also need a #10 ground, but you can use the conduit for that to save space.

If there is a ground wire run then it is MAXED out as it stands. You can have up to nine #12's in 1/2" EMT.
IMO maxing pipe fill is overfilled. This is one area where code minimum is not good enough.

Also IMO, who ever ran that pipe was either a fool or totally uninformed. You NEVER use the smallest pipe allowable and then max it out. You always run a size (or two) bigger JUST for reasons like this.
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Old 05-28-2012, 09:46 PM   #4
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Best way to add one more wire to an existing conduit


are we talking different amperages here? because i would just land the neutral wire of that 120v circuit on a breaker.... and make it 220.... unless im missing something here...
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Old 05-28-2012, 09:47 PM   #5
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Best way to add one more wire to an existing conduit


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are we talking different amperages here? because i would just land the neutral wire of that 120v circuit on a breaker.... and make it 220.... unless im missing something here...
Thing is though this is conduit, you CANNOT use a white wire as a hot. He'd have to pull it out and pull in two colors.
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Old 05-28-2012, 09:53 PM   #6
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Thing is though this is conduit, you CANNOT use a white wire as a hot. He'd have to pull it out and pull in two colors.
I know, but.... I'm with you on the 4500w load anyway...
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Old 05-28-2012, 09:53 PM   #7
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If it is a #12 it is too small for the new load.
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Old 05-28-2012, 09:53 PM   #8
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Also IMO, who ever ran that pipe was either a fool or totally uninformed. You NEVER use the smallest pipe allowable and then max it out. You always run a size (or two) bigger JUST for reasons like this.
My boss would not like this but I prefer doing it that way
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Old 05-28-2012, 09:55 PM   #9
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Originally Posted by miamicuse View Post
I have a 1/2" EMT conduit that runs from the panel to a junction box about 80 feet away, then from there another run of 45 feet to the water heater.

Not bad distance there. read on more you will see more answer come up.

The water heater is a 120V tankless. It was installed by the previous owner and cannot handle the demand. I need to put in a 50G tank heater but I need 220V.

Gaz tankless unit or a small 120 v tankless point of use water heater ?? there is a differnce on that so clearify it for us.


It was obvious to me there used to be a tanked heater there, but along the way it was changed out, what I don't understand is what happened to the 220V wiring. Unless they kept one wire and re-purposed the other? No idea.

You will have to check all the conductor and account of them to make sure the numbers/ conductor colour is correct.


But now, I have a problem because it looks like I need to feed one more wire through this run.

Read on next part this may suprised you a little.

This 1/2" EMT run is 80 feet long going through block walls, sections of inaccessible attic etc...and it already has 8 wires (5 hot 3 neutral) in them, all solid #12 copper wires and with solid wires how they tend to tangle up with each other around elbows, I have a hard time seeing how I can feed one more wire through. I tried to force a 100' fish tape forward and had a real hard time and it stuck after 20 feet.

Don't jam the fishtape in there you are pretty close to the limit of the conduit / conductor number it can be allowed in the code and is the conductor is TW or THHN/THWN ? there is a differnce on size and rating that will change a bit.

The other reason why I tell ya not to jam the fishtape due you can actually short out a conductor without a question I have see that happend before.


What is the chance of me disconnecting ONE wire from the panel end, and tie two new wires to that, and pull that wire through from the other end and hope it will work? But I run the risk of messing up one wire if that one gets stuck in the middle too.

Any thoughts?
Here my answer you will need 3 X #10 AWG THHN/THWN conductors two for new water heater and new EGC ( ground conductor ) as well

Second thing you have MWBC there so there is a good chance you have two pairs of MWBC and single circuit in there.

To change from #12 awg to #10 you will have to tie new conductors to the old #12 ( make sure all the circuits are off on this one otherwise something can short out which you will know when you pull it ) and expect to be pretty hard to pull at first but once it get going it will be not too bad at all but with TW conductors it will be pretty tough for pretty good part of run and use plenty wirelube to make it easier to pull it otherwise for myself what I do is yank the whole thing out and run all new one ( I know you will say " Nuts " to me but I have done that as well so it easier to do all at once with less effort and good excuse to check all the conductors as well to make sure there is no other damage there. )

I know there are other methold to do this but I will let other members chime in if they do know otherwise follow my methold.

Now the last part as you wondering why I say 3X10 AWG the third one is ground aka green conductor the reason why I say that due you will have 30 amp breaker and this is a correct size for OCPD I know you can get by with #12 but this is a pretty long run and I rather not take a chance on that.

Merci,
Marc
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Old 05-28-2012, 10:36 PM   #10
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Best way to add one more wire to an existing conduit


You do not need to install a grounding conductor in EMT.
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Old 05-28-2012, 10:39 PM   #11
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You do not need to install a grounding conductor in EMT.
In most case I know it generally I don't install the EGC with EMT conduit but ya never know with older installment if they were hooked up properly or it have rusted in one spot which it can comperise it.

So that is a iffy sistuation depending on OP will tell us what type of conductor if TW or THHN/THWN type.

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Old 05-28-2012, 10:46 PM   #12
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Best way to add one more wire to an existing conduit


If you can pull one wire out, pull stranded for your new circuit. You can always pull out all of the wires and re-pull with the proper sizes for your project. And if you want to spend the money, re-pull with all stranded. Not needed, but it will be easier.
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Old 05-29-2012, 07:30 AM   #13
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Thanks all.

I think I need to do some additional investigations to answer some of the questions posted. I'll be there today to take a closer look.
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Old 05-29-2012, 08:15 PM   #14
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Best way to add one more wire to an existing conduit


OK I feel like such an ass for starting this thread.

I was mistaken.

There were two wires running to the heater. Both #10.

The problem was one of them was white in color, and I had assumed it was a neutral for 120V. Once I got back to the two breakers it became clear.

So now the only issue is, what do I do with this white hot wire? The other one is black. Normally I would run a red...but the conduit is quite full.

Should I just wrap some red tape around it or heat shrink a red tubing over it and be done, or should I run a new properly colored wire?
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Old 05-29-2012, 08:47 PM   #15
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It can be marked with a sharpie, or with shrink tubing as you suggested....either way, be sure you mark it.

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