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Re: "Typical" Kitchen Appliances [Re: HotLine1] #215418 05/05/15 10:06 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline OP
Cat Servant
"I cannot grasp how a dedicated 120/20 circuit could be considered a 'code violation'? "

A 20-a circuit is a code violation when the appliance it is designed for draws less than 16 amps. Add the required additional overcurrent protection, and it's no longer a '20-a' circuit.

"please explain how a 'code minimum' design could possibly not meet code."

We've had plenty of these situations arise. I've posted plenty of such pictures here at ECN. One of my favorite examples was of an EMT conduit mounted at waist level, where it was smashed and ripped out by passing lift truck traffic.

The code does allow EMT as an 'approved' method, and EMT is often the least of the methods allowed in commercial use (local amendments). Article 110 also states that conductors will be protected from mechanical damage- and the damage clearly proves that the EMT was NOT sufficient protection.

Yet, folks will insist that EMT "meets code." Even at this forum various inspectors have not been able to grasp the idea that the NEC does provide the basis for 'disqualifying' an otherwise approved method. IMO, to assert that the NEC allows for a re-creation of something that has been shown to be inadequate protection shows a complete failure of critical thinking.

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Re: "Typical" Kitchen Appliances [Re: renosteinke] #215419 05/06/15 12:40 AM
Joined: Jun 2004
Posts: 1,273
Tesla Offline
"A 20-a circuit is a code violation when the appliance it is designed for draws less than 16 amps. Add the required additional overcurrent protection, and it's no longer a '20-a' circuit."


This interpretation reads backwards for me. I've always taken the position that a 20A branch circuit is suitable precisely when the utilization will be 80% and below.

UL listed appliances come with overload appropriate cords.

Small appliances also come with internal overload protection -- either inherent or as a component -- like a Klixon. (Common as dust inside appliances across the land, many flavors.)

Over current protection is to exist back at the panel for said 20A branch circuits.


My 2 cents on vehicle collision damaged raceways is that there are no raceways that can 'take' vehicle collisions.

Even RMC/ GRC would be crushed by a lift truck.

Fork lifts are the reason bollards were invented, IMHO.

Re: "Typical" Kitchen Appliances [Re: renosteinke] #215420 05/06/15 12:53 AM
Joined: Jul 2004
Posts: 9,623
gfretwell Online Content
The listing standard requires that the smallest digital clock or night light you can plug in a 5-15 or even a 5-20 will survive a fault on that circuit whether it is 15 or 20 amps.
The cord is required to be 18ga or sized to the load.
There are all sorts of protections built into the code and the listing that make that "less than 16a" load safe.

As for "damage" vs "severe damage", it is really what the inspector thinks is "severe". (EMT vs RMC)
The code does not try to make that call but we have the tool.

Greg Fretwell
Re: "Typical" Kitchen Appliances [Re: renosteinke] #215421 05/06/15 01:31 AM
Joined: Jul 2004
Posts: 9,623
gfretwell Online Content
I think a big part of the thinking about using 110 vs 220 was simply the way electricity, particularly AC was portrayed when they were selling the first grid, a killer. Thank old Tom Edison for that one.
If 110 was a killer, imagine what he would have said about 220.
By the time Europe was deciding on a standard, most of that was debunked.
That was interesting about the blue/brown thing tho although if they were making the ground/earth a green yellow striped conductor, it sort of makes the red/green color blind thing moot.

Greg Fretwell
Re: "Typical" Kitchen Appliances [Re: gfretwell] #215422 05/06/15 05:11 AM
Joined: May 2002
Posts: 381
Hutch Offline
Greg, A nice pictorial explanation of the colour-blind problem can be seen here.

It also give you a very good idea what the inside of a UK plug looks like if you haven't seen one before. The power cord always exits downwards making for a neat appearance in a room, especially a kitchen - the appliance can back right up to the plug.

I will note that black/white/green achieves the same colour-blind distinction. Just don't add red or orange to the mix! shocked

Last edited by Hutch; 05/06/15 05:17 AM.
Re: "Typical" Kitchen Appliances [Re: renosteinke] #215423 05/06/15 09:15 AM
Joined: Dec 2001
Posts: 2,492
Texas_Ranger Offline
I think almost all supply voltages go back to multiples of 50 to 55 V, the typical operating voltage of a carbon arc lamp. Depending on how many lamps were wired in series and how much the designers trusted available isolation materials the supply voltage was chosen. As soon as the move from local generators to larger central power stations started, system voltage became a compromise between voltage drop on the one hand and safety and available isolation materials on the other.

Almost all post-1900 electrification schemes in continental Europe settled for 50 Hz AC with large power stations and 220/380 V 4-wire local distribution. Exceptions were usually related to individual projects with particular needs, e.g. the electrification of the Mariazell railway in 1910, at the same time supplying 25 Hz electricity to adjacent homes and businesses. Here the frequency was chosen because of railway engine design issues (AC motors up to about 25 Hz can be controlled like DC motors using series resistors).

This is just a personal suspicion, but I'm almost convinced that 127/220 V systems were mainly installed to replace 3-wire DC systems without messing with the wiring.

Re: "Typical" Kitchen Appliances [Re: renosteinke] #215424 05/06/15 10:31 AM
Joined: Apr 2002
Posts: 7,261
HotLine1 Offline

"A 20-a circuit is a code violation when the appliance it is designed for draws less than 16 amps. Add the required additional overcurrent protection, and it's no longer a '20-a' circuit"

120/20 on 12AWG dedicated, terminated to a 5-20 single receptacle. Load is a micro, mounted permanently 'over the range' and ducted to the exterior. Cord cap on micro (factory) is a 5-20 male; install to mfg instructions.

Re: "Typical" Kitchen Appliances [Re: renosteinke] #215425 05/06/15 11:23 AM
Joined: Jul 2004
Posts: 9,623
gfretwell Online Content
If the problem is red and green the yellow stripe should break the tie. On the other hand maybe electrician is one of those trades that is not for the color blind. Guys afraid of heights shouldn't be roofers either. wink

Greg Fretwell
Re: "Typical" Kitchen Appliances [Re: renosteinke] #215427 05/06/15 02:25 PM
Joined: May 2005
Posts: 984
ghost307 Offline
I was very worried when I started taking my electronics classes.
Resistors and Capacitors have values 'written' using color codes (the infamous Black Brown mnemonic).
Fortunately the color combinations that would have messed me up turned out to be non-standard values that nobody would have I was worried over nothing.

Re: "Typical" Kitchen Appliances [Re: renosteinke] #215428 05/06/15 10:41 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline OP
Cat Servant
All this palaver about "internal" protections and "listing" requirements flies in the face of Article 430, which goes into motor loads. Similar provisions are found in the other nine "special cases.' The short version? A dedicated circuit is NOT a 'convenience circuit,' so you can't go by convenience circuit rules.

Maybe not the best example of "code minimum" being a code violation, but I think it illustrates how letting the codebook be your design guide (itself an Article 90 violation) can quickly lead you into violation.

As for collision protection ... yup, you got it. Article 110 says conductors SHALL be protected against mechanical damage. Nowhere does it say how you must do this- nor is it said anywhere the exact abuse a raceway is intended to defeat.

Bollards? Re-routing the line? Running the raceway within a run of structural tubing? That's your choice.

Yet I see the attitude often taken that "it's in an approved raceway and that's all I'm required to do." I disagree. Conductors are required to be protected. Existing damage is evidence that the original protection was inadequate. Thus, to return to my point, "code minimum" is, in fact, a violation.

I recently had a variation of this discussion with a shopkeeper. The feed to his street-side sign was in EMT, run through a shallow groove in his parking lot. Was this adequate? After all, no where does the code require the line to be buried at all.

I assert that, since his line has since been ripped out of the groove by traffic, the protection offered by the groove was not enough. I would point to this as proof that, in this instance, the line needs to be buried, etc.

His view is, of course, that the damage to the raceway is not a 'protection' problem, but a 'people' problem.

This recent discussion again underscores my assertion: Code "minimum" design is not only bad design, but is often a code violation. It just might take some time for the proof to show.

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