240V with no neutral? Can I build a rig?

[wyzazz]

Nevermind used a bit of Google-Fu and got a grasp of how things work. The below squared me away...

http://en.allexperts.com/q/Electrical-Wiring-Home-1734/Neutral-vs-ground.htm

 

[Ohio-Ed]

Be careful... I think this is one of those situations where by code the ground can be smaller than the other conductors. You need to make sure all the conductors are the same and correct size. If you re-purpose the ground conductor to be a neutral, it may be undersized.

 

[SOB]

Unless I'm missing something the only reason you need the neutral is because you want 240 and 120VAC...right? You dont have a 120VAC receptacle in the area or you just dont want to have to plug your rig into 2 different places?

 

[magnj]

My goals are to power 2 240v elements and 2 pumps. If i need to run a 120v line into the box for the pumps then that's an easy solution! My lack of electrical experience is probably confusing you guys.

Main goal: electric brewery, no electrical shocks or fires.

 

[magnj]

If I can safely run the elements from the 240, I don't see a problem finding a 120v to do the pumps. Was I making it too complicated?

I just want to do it safe.

 

[EuBrew]

It's always best to over think when it comes to the electrical stuff as long as you have reliable people backing up the final solution. I'd still let everyone know what your wiring looks like for your existing recep and breaker in case you do have the option of using it for 120 and 240. It's a lot cleaner to run one plug to your control panel and eliminates another source of troubleshooting if the need arises.

 

[wyzazz]

If I can safely run the elements from the 240, I don't see a problem finding a 120v to do the pumps. Was I making it too complicated?

I just want to do it safe.

The easiest solution is to just have 2 sources of power (240 & 120) feeding in to your control panel in this case.

 

[magnj]

Ok, could someone shed somelike on how the gfi would work in that case? Specifically on the 240 side...

 

[magnj]

Ok, could someone shed somelike on how the gfi would work in that case? Specifically on the 240 side...

 

[wyzazz]

Ok, could someone shed somelike on how the gfi would work in that case? Specifically on the 240 side...

You would need 2 seperate GFCI's, one for the 240 and one for the 120. GFCI's for 120V are less than $10.00 at your local big box store.

 

[magnj]

Are they available for an odd outlet like that 240 as well? That's the source of my concern and confusion, I was under the impresion that gfi used the neutral.

 

[wyzazz]

Are they available for an odd outlet like that 240 as well? That's the source of my concern and confusion, I was under the impresion that gfi used the neutral.

I've only ever seen 240v GFCI's as a breaker or as a cord. The cords I've only ever seen in 30A models.

 

[DeafSmith]

Are they available for an odd outlet like that 240 as well? That's the source of my concern and confusion, I was under the impresion that gfi used the neutral.

For the 240 volts, I think your cheapest solutions is going to be a 50 amp spa disconnect panel from Home Depot (about $50). See post #7 above for how I wired mine to my 3-prong 30 amp dryer outlet (this is for 240 volts only, without a neutral output). I use a separate 120 volt outlet for my pump with a cheap 120 volt, 15 amp GFCI - I think I paid about $10 or $12 for it.

EDIT: more info about GFCI's here:

http://www.codecheck.com/cc/gfci_principal.htm

 

[SOB]

I believe DeafSmith has said it but just to clarify a 240VAC GFCI does NOT need a neutral. It actually "watches" the current on both hots and trips when there is a difference. Which is different from a 120VAC GFCI which "watches" the hot and neutral.

Also, the Spa Disconnect panel is the way to go if you ask me. You dont need to worry about bus bars and mounting a breaker(s) as they are all in the panel. It comes with a 50A GFCI breaker installed and you can buy the same style breaker but 15A and 120VAC and snap it in to take care of your pumps.

EDIT: Sorry...since the 120VAC is coming from another source how is the breaker going to be powered since it snaps into the same bus as the 240VAC 2-pole breaker...? If you use this method then the 120VAC breaker is powered off one of the legs of the 240. Deaf, where id your 15A GFCI...in your main panel feeding the rig?

 

[DeafSmith]

EDIT: Sorry...since the 120VAC is coming from another source how is the breaker going to be powered since it snaps into the same bus as the 240VAC 2-pole breaker...? If you use this method then the 120VAC breaker is powered off one of the legs of the 240. Deaf, where id your 15A GFCI...in your main panel feeding the rig?

I'm using the spa box only for 240 volts from my dryer outlet to power my stove. The 120 volts for my pump is from a standard 120 volt wall outlet. The 120 volt GFCI plugs into the wall outlet and a regular 120 volt outdoor extension cord plugs into that GFCI. So I really don't have a main panel on my brew rig, just a manually controlled electric stove (rebuilt drop in rangetop) powered with 240 volts, and a single March pump on 120 volts. All manual, no automation.

 

[magnj]

So I'd be looking at:
240V @ Wall -> Spa Panel w/50a gfci -> Rig control box <-120V extension cord <-120v gfci @ wall

2 separate power sources to the control box. The 240V powering the elements, the 120V powering the pumps?

 

[wyzazz]

I'd mount the 120v GFCI in the control box just for kicks, unless you already have one mounted where you're brewing.

 

[magnj]

Ok, any particular reason? I thought it was more of a plug in type thing?
Any suggestions on spa panels?

 

[Ohio-Ed]

I would not run two sources into the same control panel.
If you have to use a separate source for the 120v pumps, I'd have a searate box to run them.

Besides all the opportunities to intermix the sources inside a single box, I think of my brew days... and by the end of cleanup, there has usually been some consumption. I can see a helper / visitor / friend looking down seeing a cord laying on the floor and thinking the box is not energized.

I have no idea how far this outlet is from the main panel on the property, but I think P-J was about to suggest running a separate ground for the outlet and using the current ground wire as a neutral wire. I think that would be a great option if the conditions are right.

Ed

 

[DeafSmith]

Ok, any particular reason? I thought it was more of a plug in type thing?
Any suggestions on spa panels?

Here's the spa panel:
http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053

You can use it with a 3 prong outlet for 240 only as previously described, or with a 4 prong outlet with a neutral for 240 and 120. So probably the cleanest way is to add another wire to your outlet so you'll have a neutral, otherwise just use a separate 120 volt outlet for your pump. Ohio-Ed did bring up a valid concern about mixing the voltages in one box. In my case, I bring the 240 into a fused disconnect box:

http://www.lowes.com/pd_12587-1318-LF211NU_0__?productId=1008293&Ntt=disconnect+switch&pl=1&currentURL=%2Fpl__0__s%3FNtt%3Ddisconnect%2Bswitch

and from there to my stove.

The 120 goes into a separate box on which I have mounted a dual 120 v outlet and a toggle switch. The switch controls one of the outlets, for my pump; and the other, which is not controlled by the switch, I use for a fan to keep the bottom of the stove cool.

 

[magnj]

I guess I could build 2 separate boxes...But this is getting more complicated and more hacky than I had hoped

 

[SOB]

I wouldnt consider it "hacky" at all and it's much easier than trying to run a neutral conductor to an existing outlet.

 

[wyzazz]

I guess I could build 2 separate boxes...But this is getting more complicated and more hacky than I had hoped

Keep in mind we are just throwing out options since we really don't know what you've got over there. Everything is just speculation until you pop the cover off of that outlet. My 50A 3prong receptacle in the garage just happened to have a Neutral and a Ground run to it, you may just get lucky!

 

[magnj]

That's true. And trust me I appreciate the help! I'm headed over there tom after work. Worst case scenario I can always build system with a single 120v rims to maintain temps. We'll figure it out

 

[P-J]

...
I have no idea how far this outlet is from the main panel on the property, but I think P-J was about to suggest running a separate ground for the outlet and using the current ground wire as a neutral wire. I think that would be a great option if the conditions are right.

Ed,

That is exactly where I was going. With most older 240V systems (i.e. A 50A outlet for a stove) the power was deliveres in a 3 wire cable. The wires are Phase A (120V), Phase B (120V) and Neutral. The equipment ground is not delivered. Neutral and equipment ground were considered to be the same and is within NEC code from that time. The code was changed to address safety issues that surfaced later on. With todays NEC code neutral and ground are delivered using seperate conductors.

It would be a very simple solution to run a Ground conductor to the outlet box. It does not have to be run in the same path as the power cable.

Until magnj actually looks at his setup and determines what he has, it is really just speculation. We will have to wait and see.

 

[petey_c]

magnj, Always make any checks with the circuit breaker off. If you're going to make a sub-panel (using a spa panel 50A GFCI), then there are a few things that need to be considered. All conductors (including ground) must be in the same cable or conduit (NEC 250.32 (B), 300.3 (B)). The best way is to check with the local Bldg. Dept. or electrical inspector, because codes differ from town to town. Therefore, you'd have to run a four wire cable from the panel. If you want to change the existing 6 AWG setup to 120 VAC, you can re-identify one of the insulated conductors as neutral by using white electrical tape. The grounds and neutrals must be separated in the sub-panel. All neutrals on the N bus, and all grounds on the ground bus. The neutral bus must not be connected to the panel enclosure (bonded). If the spa panel you purchase does not come with separate ground and neutral buses you can purchase one. HD/Lowes sells bus bars that are made for a Siemans, Square D, Murray, etc. panels.
“To check the gauge of the wire, I turn off the circuit breaker then pull it out?”
Normally the wire gauge is printed on the insulation of the wire (both outer and inner). 6/3 Romex (or NMB) will have 6/3 printed on the outer jacket, then something like, 600 Volts 6 AWG, on the individual conductors. On older conductors (30+ years old, this may not be the case.) If there is no printing and you have enough slack in the panel or outlet box, you can cut a small (1”-2”) piece and bring it to HD/Lowes and ask the electric dept. guys to tell you. No need to remove the breaker, the amperage should be printed on the handle.

 

[P-J]

... All conductors (including ground) must be in the same cable or conduit (NEC 250.32 (B), 300.3 (B)). ...

Dig a little deeper into the code. There are exceptions. Try NEC 250.130 (C) for a start.

 

[bbognerks]

I believe DeafSmith has said it but just to clarify a 240VAC GFCI does NOT need a neutral. It actually "watches" the current on both hots and trips when there is a difference. Which is different from a 120VAC GFCI which "watches" the hot and neutral.

I disagree with this. The GFCI breaker I just wired in 2 weeks ago I messed up on. I ran both hots from the outlet to the appropriate screws on the breaker. Not thinking about it being GFCI, I ran the neutral wire from the outlet to the neutral bus instead of to the GFCI breaker. Anytime I put any load on the circuit, the GFCI would trip. The whole reason GFCI breakers have the pigtail is to complete the neutral path after wiring the outlet to the neutral screw on the GFCI breaker. This experience would contradict your statement that it merely watches both hots. This was a GFCI from the HD Spa Panel. There are 3 screw positions on the GFCI breaker, 2 for hots and one for neutral.

 

[wyzazz]

I disagree with this. The GFCI breaker I just wired in 2 weeks ago I messed up on. I ran both hots from the outlet to the appropriate screws on the breaker. Not thinking about it being GFCI, I ran the neutral wire from the outlet to the neutral bus instead of to the GFCI breaker. Anytime I put any load on the circuit, the GFCI would trip. The whole reason GFCI breakers have the pigtail is to complete the neutral path after wiring the outlet to the neutral screw on the GFCI breaker. This experience would contradict your statement that it merely watches both hots. This was a GFCI from the HD Spa Panel. There are 3 screw positions on the GFCI breaker, 2 for hots and one for neutral.

Methinks you need to research a bit more on how a GFCI works...

Walker has summed it up nicely here...

I can't stay away from this thread. The link posted very early (how GFCI works) has all the goods in it.

I'd like to try and summarize the clever science involved in a way that is not terribly difficult to follow, because when I read about it to gain my own understanding I found it very elegant and simple. Pure genius, really.

The key to the whole thing is a small coiling piece of metal, formed into a ring like a donut. If you take a device like this and run a wire through the center of the donut, you have the beginnings of a GFCI device. When current travels along that line through the hole, electro-magnetic forces are created around the wire. These forces cause current to start to flow through that coil, even though the donut and the current carrying wire are not actually physically in contact with each other.

When current is flowing one way (say left-to-right) in the wire, the current in the coil flows one way (say counterclockwise around the donut). When current on the wire in the hole moves the other way (right-to-left) the donut carries current in the clockwise direction.

When there is no net current moving on the line int he center of the donut, the donut coil itself carries no current.

So.... to make a GFCI detector....

All lines that are permitted to carry current in the circuit (be they hot lines or neutral lines) are passed through the doughnut hole together. The coil will monitor ALL of them simultaneously. If there is a net current flowing left-to-right, the coil carries counter-clockwise current. If there is a net flow of current from right-to-left, the coil carries clockwise current. If there is no net flow of current, the coil carries no current.

All that needs to be done then is to have circuitry that monitors the current IN THE DONUT COIL itself. If there is ever current moving around the donut in either the clockwise or counterclockwise direction at all, then that means that net current of the total group of lines passing through the center of the donut is not balanced and some current has found an alternate way of getting out of the system.

It does not matter if you are monitoring 1 hot and 1 neutral, 2 hots alone, 2 hots and a neutral, or even 101 hots and 37 neutrals.... it is totally irrelevant. All that matters is that all of these lines are passing through the hole of the magic donut coil and that the amount of current that is flowing left-to-right in some of the wires in the group is also flowing right-to-left in other wires in that group.

 

[bbognerks]

A GFCI breaker works by monitoring the difference in current between hot and neutral, regardless if it's 240v or 120v.
http://www.ehow.com/how-does_4898026_gfci-circuit-breaker-work.html

That is how it works. GFCI breakers have pigtails for a reason. They will not work without connecting the neutral from the receptacle to the breaker.

GFCI CORDS are different. I have no say on that. But GFCI BREAKERS must have the neutral connect to work. I was merely disputing the statement that he said it monitors both hots to check for current differences.