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Thread Number: 86800
/ Tag: Vintage Dishwashers
Question on Amperage Warning on Kitchen Aid Superba 21 |
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Post# 1113732 , Reply# 1 4/4/2021 at 20:01 (1,116 days old) by combo52  (50 Year Repair Tech Beltsville,Md) |
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KD-21 DW | ||
| Post# 1113733 , Reply# 2 4/4/2021 at 20:18 (1,116 days old) by qsd-dan (West) | ||
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Post# 1113797 , Reply# 5 4/5/2021 at 13:30 (1,116 days old) by LowEfficiency (Iowa) |
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 Technically, that label wants you to do two things: 1) Make sure your wiring isn't undersized. 2) Make sure your breaker isn't oversized. Using an existing 20A circuit, without reducing the breaker to a 15A, would be going against #2. It's hard to say whether that is OK or not without knowing why Kitchenaid specifically stated 15A maximum. But it would have been a lot less work for them to say "15A or greater" for both wiring and fuse/breaker, so I'm inclined to believe that they had a reason for the 15A limit... | ||
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Post# 1113907 , Reply# 6 4/6/2021 at 13:29 (1,115 days old) by kb0nes (Burnsville, MN) |
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So if you use a Time delay fuse or circuit breaker then you can use 100 amp unit?
Whoever worded that tag did a lousy job. I can't imagine installing any vintage dishwasher on a branch circuit under 20 amps. Any serious fault in the dishwasher will trip either size breaker. And yes it should be grounded and no GFI should be involved. | ||
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Post# 1113998 , Reply# 9 4/7/2021 at 15:30 (1,114 days old) by LowEfficiency (Iowa) |
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Generally I believe that is true. The exception that I know of are GFCIs, which NEC requires for dishwashers, and is obviously more of a person-protecting mandate than wiring-protection, otherwise it would have been an arc-fault or dual-function requirement instead. I'm not sure when the GFCI requirement was introduced (210.8(D)), but it looks like it might have been 2014? | ||
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Post# 1114003 , Reply# 10 4/7/2021 at 17:45 (1,114 days old) by combo52 (50 Year Repair Tech Beltsville,Md) |
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Most US Appliances Do Not Have Any Fuses Inside Them The Branch circuit breakers in the panel box provide protection for either house circuit faults or any faults that occur in the appliance.
In the US every permanently installed appliance is to have its own circuit with proper fusing for the branch wiring and what ever the appliance maker stipulates.
98% of all US DWs will work fine on 15 amp lines although they are usually installed on a 20 amp breaker.
In the US 120 volt circuits are never fused for more than 20 amps for use inside a home.
John L. | ||
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Post# 1114080 , Reply# 12 4/8/2021 at 19:49 (1,112 days old) by chetlaham (United States) |
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Post# 1114160 , Reply# 13 4/9/2021 at 22:53 (1,111 days old) by LowEfficiency (Iowa) |
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>> Minus usage and listing, what code rule requires that every permanently installed appliance have its own circuit?
I'm not an electrician by trade, so I Googled that... and found plenty of debates. Specifically debates where electricians and inspectors disagree, and other instances where local codes vary. My impression from what I've just read is that (for the dishwasher specifically), it isn't "directly" required... for example, an appropriately sized circuit could supply the dishwasher and under-sink food-waste disposal, as both are permanently mounted, so long as no other lighting or general-purpose or small appliance receptacles share the same circuit? Reading through my copy of the 2017 NEC, I *did* find 422.11(A) though. Maybe this is what you were hinting at with the qualifiers in the first part of your question: "If a protective device rating is marked on an appliance, the branch-circuit overcurrent device rating shall not exceed the protective device rating marked on the appliance." Based on that wording, my impression is that a device such as the one this thread is about *would* require a dedicated branch circuit by code, as it (A) must have a circuit supplying at least 15A, and (B) cannot have overcurrent protection of greater than 15A, therefore leaving zero capacity for anything else on the circuit. | ||
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Post# 1114170 , Reply# 14 4/10/2021 at 01:48 (1,111 days old) by chetlaham (United States) |
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Now your thinking! :)
If the instructions or nameplate call for it technically you need a separate circuit and/or a specific over current device rating. Per code this DW must be on a 15 amp breaker. Wire supplying it can be larger ie 12 or 10 AWG however 15 will do.
Though the key word is technically. Don't listen to me when I openly preach about violating the codes :P as I would not lose any sleep having that on a 20 amp breaker. Or tying in the disposal as long as both did not exceed 20 amps.
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| Post# 1114205 , Reply# 15 4/10/2021 at 16:35 (1,111 days old) by sprog (Boston) | ||
Dave nailed it! 
From a purely safety perspective, you don't want to exceed the rating for the appliance, hence the 15amp fuse/breaker limit for your dishwasher (with a dedicated circuit). Anything more, e.g. a 20 amp breaker, exceeds the rating and you may risk a fire (within the appliance itself). Can you get away with a 20 amp breaker, sure, but I second Dave's take. Especially for a vintage appliance.
So, one dedicated circuit, one breaker. | ||
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