Hot tub Breaker tripping on 120V connection, 240V works fine

While trying to get a hot tub up and running, I have a breaker problem.
With any connection with 120V (using a line and neutral wire), the breaker trips.
If I only connect 240V connections, being the pump and the heater, with the contactor and pressure switches bypassed, the tub runs and heats up.
On 120V, there is only a light bulb, and a contactor, which is fed through a pressure switch and limit switch.
If either of the two, light / contactor, are connected to 120, the breaker trips.
The possibilities I see are: 1. Both the light circuit, and the contactor are shorted to ground. 2. The electrician who installed the 240V circuit did something strange.
I am having trouble beleiving both circuits are shorted, that would be too much of a coincident.
I do not completely understand 240V breakers. Could I have a version that requires complete current balance on 240V? If only 240V connections are attached, there should be no current on the neutral wire. This case runs fine.
In the event 120V is connected, current (a small amount) should exist on the neutral wire.
Why is the breaker tripping???
I suppose my next step could be to detach the wiring from the tub, and just try to power a lamp or something to ensure it is nothing in the box...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Is the breaker that's tripping a GFI breaker?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Mikepier wrote:

I believe so... I had it installed by an electrician, and it should be to code for a hot tub.
Before I call him back, I would like to know if it is indeed somthing he did, and not me! Otherwise, I have to pay!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Just to add, the electrician installed the 240V before I had the hot tub. I connected the wires to the hot tub myself, but am fairly confident I made all the right connections. The 240V works, but it appears that any 120V connection (between either of the hot wires to neutral) causes the trip.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That is correct. By pulling 120 volts from one side of a 2 pole GFCI breaker you are creating an imbalance which trips the breaker by design. If your hot tub requires a 240 volt circuit and a 120 volt circuit you will need to run a separate 120 volt line. You cannot tap off of one side of the two pole GFCI breaker. Did your electrician know about the 120 volt requirement when he installed the wiring?
How many amps is the 240 volt line rated for?
John Grabowski http://www.mrelectrician.tv
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"That is correct. By pulling 120 volts from one side of a 2 pole GFCI breaker you are creating an imbalance which trips the breaker by design. If your hot tub requires a 240 volt circuit and a 120 volt circuit you will need to run a separate 120 volt line. You cannot tap off of one side of the two pole GFCI breaker. Did your electrician know about the 120 volt requirement when he installed the wiring? "
That's strange, cause I have a 240V line with GFCI in the breaker box that is run to my spa. It's a conventional 240V line, two hots, neutral, ground. The spa uses 240V only for the heater, everything else is 120V. And it works! I assumed a 240V GFCI worked by making sure that the sum of the currents on the two hots and neutral was zero.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Looking at some website, it appears their are two different flavours of 240V GFCI breakers. 1 supports the 120/240 mix, and one is strictly only 240. Looks like my electrician gave me the wrong one.
I'll give him a call... There seems to be two ways to fix it. 1) Get a new breaker supporting the mix mode, or 2) Run a seperate 120V GFCI, which my outlets on the house already are.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Looking at some website, it appears their are two different flavours of 240V GFCI breakers. 1 supports the 120/240 mix, and one is strictly only 240. Looks like my electrician gave me the wrong one. "
That's exactly the conclusion I just came to also! At least it's easy to fix. The electrician should switch it and only charge you the price difference. Sounds like he wasn't familiar with spas, as all the ones I've seen need both 240 and 120V.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Zoner wrote:

to the neutral bar and a screw connection to connect the neutral to the tub.
Bud--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Did you run a new wire for this 120 V that you wanted? or are you grounding out one of the 240V sides?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Did you run a new wire for this 120 V that you wanted? or are you grounding out one of the 240V sides?"
He doesn't have to run a new wire. A 240V spa is run with two hots, a neutral, and a ground. The heater runs on 240V, the pump can be either 240 or 120, and the blower, lights, etc run on 120V.
I would try just hooking up a test lamp without the spa connected to one leg of the 240V and the neutral. See if that trips the breaker, which should be GFCI. If it doesn't, then you know the problem is somewhere in the spa.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I guess I need to know how a GFCI breaker works with 240V...
I believe with a 120V circuit, if the amount of current on the hot wire does not equal the current on the neutral wire, the breaker will trip. The theory being the current is going somewhere unwanted, like through your heart...
However, with a 240V circuit, with 2 hots and a neutral, how does this work? It would seem my breaker is tripping if there is any current difference between the two hots, in which case using 120V is not allowed.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"I believe with a 120V circuit, if the amount of current on the hot wire does not equal the current on the neutral wire, the breaker will trip. The theory being the current is going somewhere unwanted, like through your heart...
However, with a 240V circuit, with 2 hots and a neutral, how does this work? It would seem my breaker is tripping if there is any current difference between the two hots, in which case using 120V is not allowed. "
I believe with a 240V GFCI, at any point in time, what goes out on one 240V leg must equal what comes back on the other plus neutral. If any current goes somewhere else, eg through you to ground, it trips.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Visit the web site of the GFCI breaker manufacturer-they will have the wiring diagrams for the all possible configurations......
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
OK why don't you grab an extension cord and run that to the hot tub and wire in the 120 V bulb etc off of that, if the breaker resets you have a bad wire somewhere if not your problem is in the 240 V, are you sure your using (Red/White) or (Black/White)? I'd try the extension cord first.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.