Need assistance determining correct wire for steam generator

jeralmac said:

Hello community, first time post....

I'm currently working on a bathroom renovation, in which I'm installing a 9kW steam generator/boiler. I'm a moderately skilled DIY homeowner (live in the US) and I believe I'm on the right track but would like some verification from someone who is more skilled/experienced.

The generator is a Steamcore SPA II and here are the electrical requirements from the manual:


Electrical requirements:

1. 1.Test the voltage of electricity supply and make sure steam generator with suitable electric
2. voltage is used.
3. 2.Insulated copper wire should be used with an anti-heat temperature of 90 and a
4. specified voltage of 300V. Refer to national or local electricity consumption code for
5. specifications.
6. 3.Install an independent circuit breaker between the power supply and the steam
7. generator so to provide an electricity supply with overflow protection and electricity
8. leakage protection.

Ampere Meter
The total connected load should not be more then 80% of the rating of the overcurrent devices.

Type Electrical Supply Electric current (A)
9kW 240V~ (1PH) 37.5

The data provided above are for 240V(1PH) and 208V(3PH). Consult the manufacturer for
three-phased electricity or electric voltage of other specifications. Within the steam generator,
install an independent circuit breaker so as to provide an electricity supply with
overflow protection and electricity leakage protection (ground fault interrupter.)


Based on these requirements, the 48 foot run of wire and some reading on the web, I've determined that 8/3 solid copper core romex should do the trick. Anyone disagree? With regards to the breaker, am I fine with a 40amp breaker? The part of the requirements that state "The total connected load should not be more then 80% of the rating of the overcurrent devices." leads me to believe that it might require a higher amperage breaker?

Thanks in advance!

Jeralmac

P.S. here's the manual in the event I'm missing information:

https://www.saunaplace.com/wp-content/uploads/2015/08/Steamcore-Spa-II-Manual-60m-110F-IntelliSteam1.pdf

Click to expand...

Megawatt said:

Yes you are fine with a 40 amp breaker and # 8 wire but it needs to be a GFCI breaker. The manual states that the install needs to be in a metal conduit which I wouldn’t pay any attention to that. Any race way is allowed as long as you have an equipment ground installed which 8/3 romex will give you.

Click to expand...

jeralmac said:

Hey all, So today I put the steam generator on a test stand and wired it into my main panel using the recommended 40 amp GFCI breaker (Square D QO240GFICP). It tries to power on but keeps tripping - only runs for about 2 seconds before doing so. Thinking that the breaker might be bad, I put in a non GFCI breaker and it ran just fine for about 20 minutes.

Any ideas? Is the GFCI breaker just more sensitive and I'm actually pulling more than 40 amps?

Click to expand...

Megawatt said:

You can’t run over 40 amps on a 40 amp breaker. You shouldn’t be using but 80% of the breaker rating. Running that many amps tells me the breaker is doing it’s job by detecting the wire heating up. You need to go up on your wire size and breaker

Click to expand...

• Breaker on, nothing connected - breaker remains on - trips when pressing test button. (does this indicate the breaker itself is fine?)
• Breaker on, connect steam generator, trips in less than a second.
• Pulled ground wire off ground bar in panel, everything works fine.
• Wire run is 50 feet
• Using a 5 foot rubber 50amp cord with 50amp rated outlet

jeralmac said:

OK, so I was lucky enough to get a refund on the used 8# wire and 40 amp breaker. Fished in a new 6# with a Square D QO250GFICP QO 50-Amp Two-Pole GFCI Breaker. Now, it's tripping immediately when I connect the appliance. Here's what I know/can offer:

• Breaker on, nothing connected - breaker remains on - trips when pressing test button. (does this indicate the breaker itself is fine?)
• Breaker on, connect steam generator, trips in less than a second.
• Pulled ground wire off ground bar in panel, everything works fine.
• Wire run is 50 feet
• Using a 5 foot rubber 50amp cord with 50amp rated outlet

I did some reading and it seems that when it works after pulling ground wire, it's possible there's a "differential with the ground". But I'm not sure what that means. I certainly don't want to run it without the ground.

Any tips on how to troubleshoot?

Click to expand...

jeralmac said:

I just read an older forum where someone was having similar issues and it turned out that the GFCI breaker didn't like being in the main panel with a lengthy wire running to the end point device. In other words, they moved the GFCI device closer to the appliance, within a few feet. I can't help but wonder if I should move the breaker to the appliance end of the wire run and put it in a sub panel? Thoughts?

Click to expand...

Megawatt said:

First off the neutral in your cable has to terminate on the breaker itself and the squiggle wire from the breaker hooks to the neutral bar. Yes when you press the test button it’s supposed to trip. Your GFCI breaker doesn’t trip because your cable is too long.

Click to expand...