Thanks Petey for your prompt reply!

I get that ground and neutral are not the same thing. The problem is that they are tied together at my main panel.

If I understand your suggestion, I should run a ground wire from my panel, to the GFCI, and then on to the tub. No problem. It just seems kind of odd, because it will be connecting at the panel to the exact same spot as the neutral wire. I would accomplish the same thing electrically if I tied ground and neutral together at the GFCI.

It is logical to think this way, but actually they serve two very different purposes once they leave the main panel.
You do not want the neutral to carry fault current and certainly do not want the ground to carry ANY "non-fault" (meaning load) current.
Also, if the ground and neutral were connected outside the main panel, in the event of an open neutral it is possible for the grounded parts of an appliance to become live due to the fact that the ground is carrying live current.

Thanks again, Petey!

You talked me into it! I'll string the fourth wire.

The old tub may have been a 3 wire tub. I hooked one of these up last week, it was made by Coleman. There were 2 hots and a grounding conductor, no neutral. The OP may have thought the grounding conductor was a neutral, maybe it was white.

Petey, A two pole GFCI will function without a neutral. There were some long threads on this either at ECN or Mike Holt's, maybe both. There are some 3 wire tubs out there with no neutral.

However like you said it would be dangerous to try and hook up a 4 wire tub to a 3 wire circuit.

Knapweed, when you run the grounding wire, it must be routed with the other circuit conductors to be effective. It must also be insulated, and must be the size stated on the tub's instructions. Most new tubs today are stating #6 minimum on the conductors. Hot tubs are no place to cut corners.

I think you are right about the 240v tub. They may have just run a white instead of a green. Still not actually to code.

About the GFCB. It will not work without a line side neutral. It will work without a load neutral.

knapweed.....I realize your post is a year old, but I have run into the same problem. 3 wire main panel and 4 wire hot tub. My question is did the solution work out with the GFI connecting the ground and neutral to the same bus bar in the main panel? Thanks for any help you can give me ...Gary

3 wire main panel? I'm not sure what you mean by that. Your 4 wires from the tub are two hots, a neutral and a ground. The neutral and ground should NEVER be connected AFTER THEY LEAVE THE PANEL, as Petey explained above.

If you have a 3-wire connection to the panel and a 4-wire connection from your tub, which is what the original issue in this thread was, you NEED to run another conductor for ground, which SHOULD be easy since it SHOULD be run through conduit. If it's not, it can get more complicated.. but in any event, you need the 4th wire going back to the bus bar.

Apologies if I'm misunderstanding your situation, but if you're in "the same problem" as discussed in this thread, reread Petey and Joefixit's advice, as it is most instructive.

"3 wire main panel"

ALL main panels for 120/240 V are fed from the POCO with three wires. 2 hots and a neutral, more correctly called the groundED conductor.
The groundING conductors are connected to the groundED conductor ONE time in a main panel.
They are NOT connected together again.
The groundED (AKA neutral) is a power carrying conductor.
ALL current drawn on the corresponding hot on a 120 V circuit returns on this wire.
The groundING conductor (AKA 'safety ground') ONLY carries current if a fault occurs.
It is NOT a current carrying conductor for normal operation.

So I have three wires and hooking up my new 4 wire hot-tub. These wires were hooked up when I bought the house: two hot and a neutral. I want to do this right. Can I just run a separate ground from the main box to the GFII box near my hot tub and then run the ground to the hottub from the GFII box?

Please get professional help. Tanks of water that you are going to immerse yourself and your loved ones in is no place to be screwing around.

If the wiring is in conduit, as it should be, you may be able to get an INSULATED ground wire in there in addition, though I can tell you that pulling wires in conduits that have wires in them already is not always easy.

If it's not wired in conduit, you're going to have to start over.

I'm just trying to understand this situation. I am assuming a 3-wire hot tub is like a 3-wire hot water heater - 240 volts for the heater, and a ground; no neutral needed. If the hot tub has any controls, etc. on it, they may require 120 volts, so a neutral would be needed, hence the 4 wires. I have a question: why can't an additional wire (inside a separate conduit) be used to convert the 3-wire to a 4-wire circuit?

I agree: That's what I want to do, run an additional wire (inside a separate conduit). I certainly know where the main box is but the other wires come out of the house directly into the GFII box to the old 3 wire hottub. My plan, like you described, jus t bypasses that and runs a new wire through a new conduit on the outside of the house.

NO you can not run it in a separate conduit.

I have to agree with VITH. There is no way a 3 wire hot tub was legal if the third wire wasn't a ground. Hot tubs require an insulated ground so what you may have is two hots (240V) and a ground. If your new tub needs a neutral (for 120V loads), you must properly run that grounded (NOT THE GROUND) conductor. They all have to be in the came conduit (or in the case that a cable is allowed, in the same cable sheath).

The current hottub has a red green and white - only three wires.

I assume the red and the green are each 110 for a total of 220 and then the white is the ground or neutral (not sure which. Please let me know).

The new hottub I am getting next month is a 4 wire. Can I bring a wire down from my main box or do I have to run 4 brand new wires. The run is over 100 feet.

As Ron so clearly informed me, you cannot create a 4-wire line out of a 3+1 (unless it's conduit and you pull 4 wires). I have tried to pull one new conductor through an existing conduit and it doesn't work (physically). I would pull the old wires out then add a new wire to the bundle and pull the all together. If you do that, get the colors right: black + red (each hot) + white (neutral) + green (ground).

I just reread Steve's post and can't figure out why a green was used as a hot wire.

Thanks. With you helpful advice, I will buy 100' 6/4 SOOW Wire Cord Cable, put inside conduit, and run it to my GFII box and then to the hottub. I am sure I will hear if the 6/4 SOOW wire is incorrect.

It most definitely is incorrect. CORDAGE should not be used for this kind of wiring.

What you want is something like THWN, individual conductors. Note that the equipment ground should be green and the grounded conductor (neutral) white. The other two can be any other color other than green or white.

The size depends on what the ampacity demand of the tub is. The breaker needs to be sized for the wire. This is also required to be a GFCI breaker.

Please excuse my ignorance; why can't he just place a ground rod near this sub panel to create the ground needed? Assuming the 3 wire are 2 hots and a neutral.

Because it's not permitted by the code, nor is it safe.

All the grounds in a given structure have always been required to be bonded together. Putting a ground rod in by itself would accomplish nothing. Further, current codes require even seperate structures to have the grounds tied (even if the the structures each have their own grounding system).

The issue is not getting a path to "some ground". It's getting a low impedance path back to the service ground that is important.

Let me restate what I have said before about wiring pools and spas:

TANKS OF WATER THAT YOU ARE GOING TO IMMERSE YOURSELF AND YOUR FAMILY IN ARE NO PLACE FOR AMATEUR HOUR ELECTRICAL.

We lose people due to hack pool lighting and poorly installed spas on a regular basis. GET SOMEONE WHO UNDERSTANDS ARTICLE 680 in addition to the rest of the electrical code. This one place where making slight mistakes can have devastating circumstances. Most of the rest of the code is primarily concerned about avoiding fires. This one is directly LIFE SAFETY.

Just for my own understanding, if it was the other way, 2 hots and a ground he would need to run a neutral in the same conduit. If it was a Romex in a conduit he would have to replace it because it would not be in the same sheath, or could he run the neutral with the Romex in the same conduit and be safe and code?

If this hot tub is outside ROMEX is 100% ILLEGAL and unsafe.

CORDAGE (like SOOW) is 100% ILLEGAL and unsafe, indoors or out.

ROMEX typically is not run in conduits (it's not permitted other than for short runs for protection from physical damage).

The code will not allow you to parallel a EITHER the equipment ground OR the grounded (NEUTRAL) conductor along side a cable REGARDLESS of whether it's in conduit or not. It's illegal.

Ron, is that supposed to be "not" rather than "now"?

Yes, thanks... I fixed that.

Is there anyone on this thread still?

Here is my issue. Bought an older 2 person tub. It has a 4 wire seemingly 220 wire coming from tub--goes in to a timer box where the terminals are dbl and tripled up going through those circuits--then the plug for that box coming out of it is a 110 plug and that is the only plug giving power to the tub through the timer box.

Has this tub effectively been already wired for a 125 /110outlet and I can just plug and play?

Am I safe considering the 125 plug does have a built in ground through it?

I have no idea what you're trying to say. If some DIYer has butchered this tub, get PROFESSIONAL HELP NOW. Tanks of water that you immerse yourself and loved ones in are no place for amateur electrical work.

People don't understand the bonding of neutral and ground at the main panel. If you want to risk death by electrocution pretend neutral and ground are the same thing because they're connected at the main panel. I used to think that, but after an hour of YouTube videos I realized I had no idea how ground fault electrical paths worked... Now I know enough to pay a lot more attention...

Ground is basically for lightning and does not protect you. Proper GFCI can...

My breaker box in the house has no neutral what so ever only a ground strip how do I get a neutral to hook up the gfci breaker for my hot tub

I have a 2009 hot tub with four wires red white green black. New tub coming has three. only one hot wire instead of two My wiring is the four wires How is the three wire tub connected to four?