Dishwasher and Disposal wiring.

[George Stolz]

What does air conditioning and refrigeration equipment have to do with our subject?

It's just an example of a spot in the code which applies that principle.

Granted, different panels write these two Articles, but if it's a given that equipment switched in a non-simulataneous way is automatically okay, then these exceptions don't make sense.

I am sometimes very slow, will you explain how the circuit would be overloaded? :?

I am slower than you.

It wouldn't be overloaded; I'm not saying that. I'm just saying I don't think it's code-compliant.

Dana, I have a couple problems with the approach you're taking with it.

One, we're dealing with "appliances" that are named in 422. A dishwasher is not a pure motor, it's comprised of a motor, heater, timers, Lord knows what else in there. I just peeked at mine, and saw "thermally protected" on the nameplate. It doesn't give me a value of the thermal protection, it just says protected. How can I provide proof I've complied with 430.52(A)(3)?

Second, I could use 430.52(A), (B), or (C), according to 430.52. So we could pass according to (B), if I'm reading it right.

I strongly appreciate the code reference, I'm needing to get up to speed on motors in a big way. 8)

 

[iwire]

George,

It wouldn't be overloaded; I'm not saying that.

But you did say that.

Why would we need these exceptions if threeways (or relays) allow us to "over" load a circuit?

On the other part, if what you are thinking to be true is true, then the exceptions to 440.33 and 440.34 are pointless, because it's already allowed.

They are not pointless.

As you know the exceptions only apply to the sections that they are under. Those exceptions have nothing to do with anything in Article 210.

Those exceptions to 440.33 and 440.34 are there because 440.33 and 440.34 tell us in a round about way that the conductors will be sized per each of the nameplate of the unit(s) +25% of largest being connected.

Requiring conductors to be sized on the name plate is a much different requirement than 210.19s 'ampacity not less than the maximum load to be served' and 210.21s 'shall not be less than the noncontinuous load plus 125 percent of the continuous load. '.

Neither 210.19 or 210.21 need an exception like 440.33 and .34 need.

Bob

 

[George Stolz]

It wouldn't be overloaded; I'm not saying that.

But you did say that.

Why would we need these exceptions if threeways (or relays) allow us to "over" load a circuit?

With the quotation marks, I was trying to make clear the overload was in name only, not in actual current. I'm trying to create a distinction between a "nominal overload" and a "physical overload."

As you know the exceptions only apply to the sections that they are under. Those exceptions have nothing to do with anything in Article 210.

True, but Chapter 4 is not supposed to modify the requirements in Chapter 2, so they should be on the same page on this issue. Given different CMPs it is not guaranteed, but they should be.

440 has nothing enforceable in regards to the dishwasher/disposal debate. I believe these sections are still relevant, in the precedents they create.

According to the style manual, concepts that are opposite the rule are to be written as exceptions. If they were trying to reaffirm a concept that was in line with the rule, then it would have been a second sentence of the rule. In the opinion of the writers of 440.33 and .34, they seem to believe that in general, switching doesn't change the general idea that all loads that receive their power from one breaker are on the same circuit, and are added together when determining the conductor size.

Those exceptions to 440.33 and 440.34 are there because 440.33 and 440.34 tell us in a round about way that the conductors will be sized per each of the nameplate of the unit(s) ... being connected.

I highlighted "being connected" because it's the inherent hiccup in this train of thought, IMO. If 'connected' meant 'connected to the source simultaneously' then the exceptions are a waste of ink.

Requiring conductors to be sized on the name plate is a much different requirement than 210.19 ... and 210.21 ...

I don't understand. Can you elaborate?

I see nameplate and "max load to be served" as interchangable terms; we have to accept the nameplate as the "max load to be served" in some cases, as otherwise we'd wind up with a 210 violation, wouldn't we?

Two closing thoughts:
1. I'm not convinced I'm right, I just can't see how I'm wrong. :wink:
2. One other aspect we're not discussing yet is why 220.60 doesn't include branch circuits.

 

[iwire]

I don't know what to say George. :?

To me it is clear.

The SPDT switch results in the circuit supplying one load or the other. No other mode of operation is possible.

Only one 'load' is part of the circuit at any given moment.

There is no requirement to consider both loads are connected to the circuit when in fact they are never connected to the circuit at the same time.

 

[George Stolz]

We can agree to disagree on it, IMO.

Some debates can escalate to "moral crusade" status, this one doesn't have that potential, from my seat. It's only warmed up to "more interesting than paint drying" for me.. :lol:

It was interesting to kick it around a bit. 8)

So, how about 250.32(B), anyway? :twisted: