Countertop oven w no grounding plug ?

[Marctrees]

Can anyone explain exactly where and under what conditions the "leakage current" is measured ?

Is the "ground" that the leakage is to like one side of lab xformer secondary ?



And as a seperate thing... those are allowable amounts ... what happens when a crimped wirenut put on by a chinese 9 yr old falls off and the line in now falls against the case ?

I have not had a chance yet to see if the oven nameplate has the double insulated symbol.

Marc

 

[Marctrees]

OK, All I'm sayin is - We understand why an EMT system for example is mandated grounded.

How is ANY *** electrically equivalent *** widget any different ???

Marc

 

[BillK]

Still waiting to see the data plate off the oven. I may be wrong but I am betting that it is double insulated.

 

[alfredeneuman]

Can anyone explain exactly where and under what conditions the "leakage current" is measured?

The whole .pdf file is here >>> http://remotefile.wtoqc.com/attachments/month_0709/20070918_98d7c877b8eeb1811958ocl1cux7SuAW.pdf

(1026.33.3) The leakage currents from these surfaces are to be measured to the grounded supply conductor individually as well as collectively where simultaneously accessible and from one surface to another where simultaneously accessible.

 

[Marctrees]

I looked at the oven nameplate and at the manual.

No where is there showing the double insulated logo or any words about DI.

Only talks about polarized plug.

Marked as UL listed.

Marc

 

[sberry]

If this goes on long enough someone will figure it out. I thing we need a book learned engineer.

 

[Showkey]

Is this “leakage“ .....as designed .......as build or life of the product ??????

 

[AntonLargiader]

The whole .pdf file is here >>> ...

Thanks, that's interesting, I don't see the part you quoted earlier as being much of a decision tree on grounding though. It could inform a a decision on large appliances which have a leakage current between 0.5 and 0.75 amps, but I don't see that being the purpose of the section.

Elsewhere in it:

28.6 A cord-connected appliance that is intended for more than occasional outdoor use, a motor-driven spit, outdoor electric grill, food smoker, or similar device intended for outdoor use shall comply with either of the following:
a) The appliance shall be double insulated; or
b) The appliance shall have provision for grounding dead metal parts in the form of a grounding conductor in the cord and a grounding type of attachment plug, in accordance with 28.3 (see also 60.14).
Grounding shall not be used if the product is marked as being provided with double insulation.

But that's about all I see along the lines of dictating which appliances have 3-wire. There's a lot of testing described that measures current to ground (impact tests, immersion, overheating, and so forth) to determine acceptable or unacceptable, but to me it didn't seem to be in the context of informing a 3-wire decision.

250.114 seems to control this more.

It's an interesting topic and I wish I knew more of the answer.

 

[AntonLargiader]

Looking a bit deeper into 250.114 and the 2-wire appliances in my house:

• Coffee grinder: possibly included in 3c but exempted by virtue of being listed and double-insulated or equivalent. It has an all-plastic housing so there's hardly anything to ground.
• Vacuum cleaners: probably 3c but exempt
• Ice cream maker: probably 3c but exempt
• Table and floor lamps: probably 3e but exempt. Hard to argue that they are double-insulated, though, when the metal switch bow is connected to the exposed metal and the exposed wire end is right next to the switch bow.

These do not seem to be covered by 250.114:

• Coffeemaker
• Toaster oven
• Rice cooker
• Various chargers (shaver, batteries, phone, toothbrush)

I do not see a double-insulated mark on any of these items. I don't know what the "or equivalent" means; this seems to really drive the need for grounding in some cases.

There's frequent mention of the exemption for heating elements but all I see is an exemption for metal frames in heating appliances over 150V, so nothing that would apply to residential toasters. This is looking at the 2020 code.

 

[u2slow]

Can anyone explain exactly where and under what conditions the "leakage current" is measured ?

My first-hand learning experience on the matter involves household cooking appliances being brought to work for the lunchroom. Our sites use ground-fault detection, and we get alarms. This is a trace current from line to ground. Careful isolation of the heating element (from metal chassis) eliminates the leak.

Heating devices - in general - tend to be a common source of the ground faults we encounter.