What does the nameplate rating mean?

Hello, group:
I have a new oven to install this weekend. The nameplate gives it a rating
of 6.4 Kv at 240 volts. By advanced calculus, I get 26.6 amps.
Now my question is, will a 30 amp circuit suffice, or does this thing really
use all 6.4Kv? If so, 26.6 amps is more that 80% of the circuit ampacity.
Should I run a 40 amp circuit instead?
Reply to
Warren S.
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It will when everything is on high and heating. I would run a 40 amp circuit. Never can tell how often it will be used on high.
Reply to
I would refer to the installation instructions as well. It may tell you what you need to install to maintain the equipment's listing.
Donald L. Phillips, Jr., P.E. Worthington Engineering, Inc. 145 Greenglade Avenue Worthington, OH 43085-2264
snipped-for-privacy@worthingtonNSengineering.com (remove NS to use the address) 614.937.0463 voice 208.975.1011 fax
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Reply to
Don Phillips
Don Phillips wrote
The installation instructions were not specific. I have decided to run a 40 amp power supply anyway, since I don't want to cut it that close. Thanks to those who responded. Warren
Reply to
Warren S
Warren S. wrote on Wednesday (21/01/2004) :
30 amp should prove to be perfectly adequate.
1. The rating you calculated suggests so. 2. You are unlikely to switch everything on at once. 3. Even when everything is on, the temperature controls will not all be on and drawing current at the same time.
.. And finally 2 and 3 mean that some diversity is allowed for in cooker supply ciruits within the IEE Regulations. It does sound like a rather small cooker though.
Reply to
Harry Bloomfield
Wow, 6.4 Kv huh? Mighty powerful oven!
Reply to
Warren, are you sure that it doesn't say Kw and not Kv? It makes a major difference in the interpretation.
If it is Kw, a 6.4 Kw load operating at 240 volts resistive load will draw 26.66 amps as you correctly deduce.
While you could operate it from a 30 amp breaker, you may run into intermittent trip problems with the breaker when the oven is running at full capacity for an extended period of time. I'd personaly go for the next higher capacity breaker, be it 40 or 50 amps, but be sure to size the wire guage accordingly.
For 50 amps, I'd run #8 wire, although #10 may marginally satisfy NEC requirements (I don't have a copy of the NEC handy here at home). Another factor is the distance between your distribution box and the oven, but I'm assuming that it is less than a 50-ft wire run. Realize that the cost of the wire is likely the least expensive thing in the project, because that wire will likely be there to provide service for many years.
Licensed Electricians, please correct me if I'm wrong here, because I don't want to steer the guy in the wrong direction and most of my practical experience here is with 3,000 MCM or larger traction power cables on subways and #24/26 signal and communicatons wiring. I also generally assume that #14 is used for 15 amps, #12 for 20, and #10 for 30 amps, so I'm not entirely sure that #8 is adequate for a 50 amps (but didn't want to suggest #6 which many homeowners have problems working with).
My personal preferance here would be for a 40 amp breaker feeding #8 wire, however I'm not sure if 40 amp breakers are readily availble for domestic distribution panels, but I know that 50 amp breakers are.
Then too, I'm a control system guy, so what do I know! :-)
Harry C.
Reply to
Harry Conover
Your recommendation of #8 Copper and a 40 amp breaker is most likely correct for this installation.
There are many variables the OP didn't share with us. Manufacturer's installation instructions, system supply voltage (not the appliance rated voltage), method of connecting circuit conductors and their temperature rating, etc.
Many installers take the amperage figures of the NEC Tables (i.e. 310.16) under the insulation classifications as the permitted current capacity of a branch circuit wire. While in some cases this could be the case, often there are other non-apparent factors that could limit the current allowed for a specific size conductor. One of many such possibly limiting factors is the temperature rating of terminating devices. If the terminal temperature rating happens to be listed at 60 deg., the amp rating of even 90 deg. wire would be limited to 60 deg.
With the NEC what might appear to be a logically correct choice might be disallowed by other factors.
Louis-- ********************************************* Remove the two fish in address to respond
Reply to
Louis Bybee
Louis Bybee wrote
It just says to connect to a circuit appropriate for the nameplate rating.
My Fluke says 241.3 volts
Blue wire nuts at the oven j-box, circuit breaker screw terminals at the panel. IIRC, 75 degree rating.
I've decided to run #8 THHN in alflex, to a 40 amp breaker. Another poster caught my error listing the oven's rating at 6.4Kv. It is, in fact, 6.4 KW.
Thank you for your reply. Warren
Reply to
Warren S
Nope, we know nothing about how powerful it is, just that it has a weird dual voltage rating.
Reply to
Steve Alexanderson

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