Commercial dishwasher wiring question

walunitMay 5, 2010

I have a Hobart SR24H dishwasher with 4 wires + ground (They are marked with 2 reds 1 black and one white + 1 green ground) Is the a 3 phase unit? It should be a 2 pole breaker. Do you wire 2 reds on one hot side, the Black to the other hot and the white to neutral?

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Why this question on a do-it-yourself forum? Commercial work requires licensing.

    Bookmark   May 5, 2010 at 12:50PM
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Ron Natalie

You need the manual for the dishwasher. The thing is NOT 3-phase. It requires 3-wire 240 or 208 hook up. I suspect that two of the wires go to the hot legs and one is fed to the 120V only plus neutral plus ground.

    Bookmark   May 5, 2010 at 2:24PM
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3 phase and a triple breaker. You have to either get or have a 3 phase service or call Hobart and see if they can rewire it for 240 single phase.

    Bookmark   May 5, 2010 at 2:25PM
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That system is 3ph with a neutral. 240-120. It will work on 208 and NO you cannot wire it that way. You can but it won't work.

    Bookmark   May 5, 2010 at 2:28PM
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Ron Natalie

SORRY, but the last two posters are COMPLETELY AND UTTERLY INCORRECT.

I checked this before I posted. The unit is NOT THREE PHASE. NO WAY NO HOW.

It requires 208 or 240 single phase AND it requires 120 single phase. What is missing from the SPEC sheet I have is the color of the wiring,

It requires 37A at 208 or 240 at 42 SINGLE PHASE and recommends a 50 AMP breaker.

The best answer is that if this is being installed in a business, the OP has no business trying to hook it up himself, but I can tell him that for planning purposes what he needs for power.

    Bookmark   May 5, 2010 at 5:00PM
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The specification for the 120/208 and the 120/240 hookup call for a 3 wire plus ground hookup according to the pdf spec sheet. What is the 5th wire for and why would a 120 be run separately?

    Bookmark   May 5, 2010 at 5:21PM
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3 hots plus neutral plus ground.

    Bookmark   May 5, 2010 at 6:09PM
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I've worked for and installed Hobart eq. for over 7 years.
Don't argue with me. You have a 3 ph system. 4 wire with ground. The neutral is used for the timer.120 volts. Ronnatalie. You might want to check OHM's law. what you say is not possible. the higher the voltage the lower the breaker amps.

    Bookmark   May 5, 2010 at 8:57PM
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walunit; you're not allowed to do this. yada yada yada.

Meanwhile, in the real world...

According to the manual, the machine requires three #8 AWG conductors, which INCLUDES a current-carrying neutral... so the connection INTO the machine will be two hots, one neutral, one ground.

The manual also indicates that the connection diagram should be provided on the machine itself. If it is not, we need to guess.

I personally suspect that your initial guess (black = L1, both red = L2) is correct. I'm guessing there was originally a terminal block of some kind, with the reds already attached together on the machine side.

If this is NOT the case, I would have to wonder if your machine is missing something, since, fully intact and with all of its original terminal blocks and accompanying diagrams, there most certainly should NOT be three hot conductors.

Sorry folks, I haven't left yet.

    Bookmark   May 5, 2010 at 9:07PM
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According to Hobart's manual on their website, this unit will work on 120/208 (generally speaking, by using 2 out of 3 legs of a 3-phase system, without getting into a high leg discussion.) So, while it can be hooked up to a 3-phase panel, the washer itself is NOT 3 phase.
It will also work on a single phase 120/240 volt system.
I do not understand why there are 2 red wires. Again, according to the manual, it requires 3 wires (normally, black/black/white or black/red/white) plus a grounding wire.
You need an electrician anyway, so just call one and let them deal with it. You're good to go whether you have 3 phase or not.

    Bookmark   May 6, 2010 at 4:06PM
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One thing i don't understand and it is so simple. Why not look at the specs. plate rivited to the washer. It will tell you what voltage and what phase. It's right there.
Every hobart washer i've installed that has what is called
" 4 wire with ground is 3 ph. " That gives you 5 wires. Gound is NOT counted as a current carring wire. The neutral works the timer and the dump valve for the drain. 120 for the timer and 220 for the valve. 3ph for the booster. that is what the " H " stands for in the model number. "24" is the size. Yes this can use single ph. but hope you have lots of money when the hydro bill comes in. And it will be very slow to heat. A lot of you guys are right and alot of you guys are almost right. good luck.
Why do you have a commercial dish washer ? They DO NOT wash
dishes as in a residentual dish washer. They are a sanitizer. They have a 3-1/2 minuet cycle. Every dish that is put in that washer HAS to be pre washed. I do still have the test strips to test the rinse heat of that washer.
I can send you some. This is no joke. Department of health
test strips. E-mail me if you want. Good luck. forgot one thing. How many terminals on the contactor ?

    Bookmark   May 6, 2010 at 5:57PM
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Walunit, it's not only that "you're *most likely* not allowed to do this", but from the sound of your original post it doesn't sound like you have nearly a clue about this stuff. Even more reason to hire someone who does, and has the proper insurance and credentials.

Do the right thing, will ya.

    Bookmark   May 6, 2010 at 7:17PM
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Not to mention the plumbing.

    Bookmark   May 6, 2010 at 11:37PM
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