What size wire for electric double oven?
Schwenker
| Posted in Construction Techniques on
Wire coming out of the back of the double ovens is 10 gauge. Guy at the electrical supply house sold me 6/3 gauge wire saying that is standard for ovens. I’m just a diy’er but common sense tells me that if 10 gauge is what the manufacturer has coming out of the oven, 10 gauge should be fine to run back to the panel. Running 6 gauge up to the junction box to where I will hook into the wire from the back of the oven isn’t going to help (only as strong as the weakest part theory). Am I OK running 10 gauge from the panel? Thanks in advance for your help!
Replies
NEGATIVE on the 10 ga. Do not run it.
What is the nameplate rating (it will be 5kW or so) on the oven and how far from oven to panel?
MERC.
The wire needs to be of a size appropriate for the breaker.
if i remember right my oven called for a 40 amp breaker,which takes a # 8. i was runing about 35' so i went to a #6. i know what your talking about but if my insp. would see 10 on a 40 amp, i'd be red tag! larry
Depending on the rating, usually #8 for a single oven and #6 for double oven.
#10 just won't fly. Don't do it.
You're really lucky that you asked. Your common sense approach may well have gotten you a burned down house.
The appliance wire--the 10 gage stuff, called the "appliance whip"--is different in many respects than the building wiring. First, the whip is of different construction. The insulation on the appliance wires has a higher temperature rating, and the wires in it are in a metallic armor (right?) If the whip overheats, being inside a metallic armor means little chance of fire. Second, the whip is not inside the wall of the house, surrounded by thermal insulation. This means that the whip can dissipate heat better than the cable in the wall. Third, the appliance whip is short, a couple of feet, compared to maybe 50 to 100 feet for the building wire, and isn't fed through and stapled to the building framing. This means the whip is less likely to be damaged.
Why is the whip allowed to be smaller gage? Because if you used AWG6 wire on the whip (even a very fine multi-strand like welding cable), it'd be really difficult to push the appliance back into place.
If you had installed 10 gage cable (and used the 40 or 50 amp breaker required by the appliance), that cable would be seriously overloaded at some point. Keep in mind that a breaker does not trip instantaneously until the current is 5-7 times the rating of the breaker. So a 50 amp breaker could allow 150 amps to pass for quite some time--several minutes. That 10 gage wire would really heat up in the mean time. A few overheating cycles, and the insulation will fail. During the next overheating cycle, due to expansion, or maybe from building vibration, the wires touch. Maybe that creates an arcing fault, throwing sparks. An arcing fault often won't trip a normal breaker. Result--a fire. Think there are a lot of "maybes" in the scenario? This sort of thing happens, and there's no reason to tempt fate by using wire that's too small.
There are a lot of ways to do an electrical installation wrong, and some may lead to a fire or shock/electrocution danger--even though the installation will seem to work O.K. (for a while).
It's good that you asked the question, and it's a perfect example of why anyone who wants to do their own electrical work should get and read a good book on residential electrical.
I recommend Cauldwell's book "Wiring a House" and also Traister's, "Electrical Wiring-Residential".
Enjoy the new oven.
Cliff
Most people think that wire is rated at one current and one current only and don't realize that wire construction and application, and enviromental conditions can in some cases allow wire to carry more than the "standard ratings" and in other cases less.
"If you had installed 10 gage cable (and used the 40 or 50 amp breaker required by the appliance), that cable would be seriously overloaded at some point. Keep in mind that a breaker does not trip instantaneously until the current is 5-7 times the rating of the breaker. So a 50 amp breaker could allow 150 amps to pass for quite some time--several minutes."
But a slight correction on the trip times. Here are the charts for the Cutler Hammer CH and BR series breakers.
http://www.eatonelectrical.com/unsecure/cms1/TD01201014E.PDF
http://www.eatonelectrical.com/unsecure/cms1/TC00302001E.PDF
At 300% rated current the trip time is 4-20 seconds. This is the thermo trip curve and varies from upto never at about 120% load to 1-3 seconds at 700% rated current.
The instaneous trip is magnetic and it is not directly related to the current rating.
For the BR breakers in the 45-60 amp range it is 450 - 750 AMPS.
For the CR breakers in the 25-50 amp range it is 350 - 750 AMPS.
Instaneous trip time is 20 millisec or less.
Bill,
Thanks for catching my error. I guess it just seems like minutes...
Anyway, how about those Red Sox? Actually, I'm just happy to have a Yankees-free Series! I'd like to see it go seven games, just cuz I like the game, and also I was a fan of LaRussa when he coached the Athletics.
Cliff
Thanks a bunch for taking the time to provide a detailed response. I will run 6/3 the whole length back to the panel (about 35'). I couldn't find any kw rating on the oven or in the manuals supplied.
In the oven manual, it showed the junction box (where the appliance whip is joined to the house wire) surface mounted to the wall behind the oven. Is this common practice, or should I recess the junction box level with the surface of the wall? I'm not sure how I'd have the appliance whip enter the junction box if I recess the box (unless a cover plate is made with a whole in the middle for the conduit strain relief clamp).
It does not make any difference if the j-box is surface mounted or recessed. Just need to make sure that there is enough space after the oven is installed.
And yes, there are standard metal coverplates with holes in them for the connectors.
The rating of the oven is on the nameplate.
The rating of the breaker determines what sort of outlet you install. Generally this will be either a 30-amp or 50-amp outlet.
Don't forget to install 4-wire (3+ground) cable and a 4-wire outlet.
If he is using the factory whip I think he would be going in to a box, not a receptacle. I am not too sure anyone who does not know that they make box covers with knockouts should be wiring anything of this magnitude.
Not everyone knows everything like you. That's the reason I research what I'm doing and visit this site, and in most cases, I get intelligent responses. Oh, it's real hard to match up a red wire to a red wire,black to black and so on. I'm surprised that you didn't jump on Dan since he didn't know that you have to direct wire an electric wall oven and not use a plug (like a range). Thanks to CAP (and others), I have my oven wired (6/3 w/grnd) and working fine.
I am not an electrician but do some work on my own and for some others working with an electrician. No I do not know it all. I was just judging from some of your questions that you are more than likely in over your head. While it is well advised to ask questions like you have, the work you are talking about doing is a good bit more risky than adding a receptacle or changing a switch.
I also based the judgement on the fact after you asked the electrical supply house you thought 6/3 was overkill. There are a lot of subtle mistakes one can make on a project like this if you do not have a good command of the knowledge and training required. If your range does not have a data plate with it's ratings I would be surprised and would question hooking it up. There are new gee-whiz electrical parts I find every time I go to HD or the elec. supply house. However a junction box cover with a knockout for a strain relief is not anything new.
Sorry if you thought I came down too hard on you. If you can find an electrician to work with you to tell you what to do then hook it up for you you will probably will be better off than getting even the very good advice to be had here.
Pay attention to how the appliance cord orients to the outlet. You want to mount the outlet so the cord will fold neatly out of the way when everything is buttoned up. (Often this is sideways.) And of course make sure the outlet won't interfere with the oven structure.
Electrical resistance in a wire is determined by TWO factors Wire gauge(dia.) AND length!!!
The manufacturer put a 10ga. , 4ft. pig tail on the oven
You gonna run less than 4 feet??
I thought not.
Read the instructions!
follow your local code!
Hire a proffesional before you burn your house down!
Yeeesh!
Mr T
I can't afford to be affordable anymore
It amazes me how many people take the time to reply about topics they aren’t qualified to comment on! I mean common people, take up a hobby or something where you can’t cause harm to someone or their property.... i.e. Residential electrical Work!
Regarding size wire required for an oven or any other non motor load, look at the nameplate of the appliance/ device and find the Load rating, which usually is in watts or VA... or KWs or KVA ( 1000 watt/VA Increments ) .... and sometimes in amps! If amps are shown, It’s easy... if not, divide the nameplate rating by The voltage shown on the nameplate . If it is a 240 volt appliance/ device, use 220 for the division ( it’s because there are many places where the available power is actually less than 240volts AC. ) . For a 10KW oven, divide 10,000 ( watts ) by 220 (volts), which equals current (AMPS). Once you have the amperage determined, consider distance of wire run from panel to the appliance. This Is needed to determine voltage drop (vd) and is a more complicated equation. Rule of thumb differs amongst tradesmen, but in most cases, if the distance of the run is 50ft or less, it does not create enough voltage drop to require a wire size upgrade .
So 10000 divided by 220 is 45.45. ( amps ). Based on NEC tables, #8AWG modern THHN or THWN copper wire is adequate for up to 50 amps ( up to 50ft run for my installs). Use a 45 amp for safest install because it will protect the appliance better than a 50 amp breaker. On a 12 KW oven, 54.45 amps is the load which will require #6AWG wire ...... again for runs up to 50 amps. For runs over 50 feet, I recommend calculating the voltage drop which is available online easily...
By using 220 as your figure to divide the load ( watts ), you already have an allowance built in for proper wire and breaker size.
So the bottom line is DO NOT WING ELECTRICAL WORK!..... especially in your own home where you or your family reside! Do not think for a minute saving on wire size... but Do compute the load as written.
If you ever hear a “brief “buss” in a building when a large load ( AC, Compressor, etc ) turns on , it Is the conductors ,that feed the device/system, vibrating because they most likely are too small!.... If they were in the open in view, You could actually see them move!!
Enough for electrical 101!
Good luck