Is it safe to replace a 2500 W oven bake element with a 3000 W element?"

Hi all

my stove is a 1971 Moffat Maitre D, 30 inch, model 30 T 68, (45 years old!) .

When I do my research, I found that Moffat was part of GE. unfortunately, I didn't write down who advised me to buy a Universal UB963 element when I g ave them the model number. I am afraid it is incomplete advice, no mention was made of short prong, long prong. It was the wrong advice I think.

I'll call Reliance to ask about the prong length of that model. I only lear ned after the element was replaced that the wattage info was on the back o f the stove.

Any help would be very much appreciate it.

Thanks a lot.

Reply to
leza wang
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I didn't write down who advised me to buy a Universal UB963 element when I gave them the model number. I am afraid it is incomplete advice, no mentio n was made of short prong, long prong. It was the wrong advice I think.

arned after the element was replaced that the wattage info was on the back of the stove.

Unless you somehow know that stove was rated for a 3000W element, which seems very unlikely, the answer is no. The wiring and other components in the stove were rated for 2500W and 3000 can exceed the safe rating for those. Possible issues with wiring to the panel and breaker too.

Reply to
trader_4

I didn't write down who advised me to buy a Universal UB963 element when I gave them the model number. I am afraid it is incomplete advice, no mentio n was made of short prong, long prong. It was the wrong advice I think.

arned after the element was replaced that the wattage info was on the back of the stove.

I'm confused. Has the element already been replaced? Did you replace it, th en see the info on the back of the stove and then *not* turn the stove on?

I'm also confused about how the prong length enters into this if the elemen t has already been replaced. Did the new element appear to fit correctly? Do the prongs on the new element match the prongs on the old?

Reply to
DerbyDad03

y, I didn't write down who advised me to buy a Universal UB963 element when I gave them the model number. I am afraid it is incomplete advice, no ment ion was made of short prong, long prong. It was the wrong advice I think.

learned after the element was replaced that the wattage info was on the ba ck of the stove.

Can't she just cut 20% off of the 3000W element? ;-)

Reply to
DerbyDad03

No, that would change the resonant frequency and set up harmonics that would keep the neighborhood awake.

Reply to
Stormin Mormon

If you're going to take the element out anyhow, it shouldn't be hard to take it out before buying the replacement, and measure and take a picture of the prongs. OTOH, if you buy long prong, you can cut them shorter maybe and then grind or sand off any burrs left by cutting.

Not that I've ever done any of this.

You call this help? I would guess that it's fine, at 240 volts it will still be under 15 amps. Right?

Reply to
Micky

Derby points out that you seem to have already replaced it. This points out another reason I don't like it when there is info in the subject lline that is not in the body of post. It exists outside of context (Is that logically possible?) and so it's importance and relevance to the whole post is unknown. Where would it have fit if ou had put that sentence IN the post, not outside it?

Also, the wattage might be in the back but isn't the model number in the front, behind a door perhaps? From that you should be able to get the wattage of the stove and of each element.

I found on the web that in " Bertazzoni ovens, apparently the baking elements they contain are high in wattage. 2100 watt for the top heating element and 3400 watt for the bottom heating element in each oven cavity." So that causes me to ask what is the rating of the other element. I'd be super surprised if you couldn't make the smaller one as big as the bigger one and not overload anything (in addtion to what I said before.)

Reply to
Micky

A good place to buy flour, although online the cheapest order is $40CN The mill has been in continuous operation for 197 years and half of it still runs from water power. Much of the equipment is over 100 years old.

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Reply to
Micky

On Tuesday, May 24, 2016 at 1:19:51 PM UTC-4, leza wang wrote:

I don't usually dig up old threads, but there is a safety issue here. The simple TLDR answer is NO! It is not safe to replace a 2500W element with a 3000W element. Unless, ALL other parts of the system are checked to see if it can be done safely.

I will use my 1974 Tappan Olive Green model 31-1234-17 to demonstrate. BTW it would blend right in to the Brady Bunch kitchen. The bake element in my oven is similarly rated at 2400W and may be discontinued as other elements are. The upper broil element is rated at 3000W. I found this information on one of two wiring diagrams on the back panel. The specification plate states at 250 AC the unit is rated at 11.8kW or 11800W total which when divided by the voltage gives an amepage rating of 47.2A. So 11800W - 2400W - 3000W = 6400W remaining to account for, the rating is probably ignoring the less than 1% couple of watts the clock motor consumes. It has a single 8" stove element and three 6" elements which have all been discontinued. It also has a oven mode selector switch which has Off, Bake, Timed Bake, Broil, and Preheat. The switch has been discontinued and the replacement knob is currently special order only and at $82 plus shipping, I would replace it with a four or three position universal model for less than the price of the knob. The two selections that would go are preheat and timed bake and that is relevant to the bake element replacement consideration.

I currently have a 2600W 8" element and three 1500W 6" elements along with all new ceramic sockets, wiring, and infinite switches for the stovetop. I have also replaced the oven thermostatic switch. All other stove wiring remains original. These add up to 2600W + 1500W + 1500W + 1500W = 7100W or 7100W - 6400W = 700W more that the manufacturer designed, bringing the new total to 12.5kW or 12500W which is an amperage rating of 50.0A. 50A is a typical standard branch circuit ampacity for an electric range. That is what serves it now with proper three conductor 6 guage with ground and a four prong 50A grounding outlet, before it was moved it was on the same guage wiring with a 50A three prong non-grounding outlet and only a 40A circuit breaker, but never tripped the breaker.

The only time it would use the maximum is if all elements were on full at the same time. So this means I would have to turn all top burners on High and set the oven selector to Preheat which turns on both the upper broil element and lower bake element bypassing the thermostat. We never did that on the 40A breaker nor the 50A breaker. Our maximum usage of the unit is for a holiday meal usually involving roasting a large turkey or baking a large ham. Only one top burner is used to prepare stuffing or glaze while the oven may be on preheat or in wattage/amperage is at most 2600W 8" element + 3000W upper broil element + 2400W lower bake element = 8000W which divided by 250VAC is 32A. For a few hours the cooking drops to only the bake element cycling on and off per the thermostat to maintain the average 300-400 degree F set temp which will be lower than 32A. Then the other fixin's will begin and maybe all four top elements used but at most maybe two on High at any one time, but let's just say we are going full tilt on top and use all 7100W at once while the 2400W bake element is on for a total of 9500W or 38A. And as manufactured that would have been less at 8800W or 35.2A. So in neither case would the 40A breaker trip.

Now to consider a 2400W bake element upgraded to 3000W. We will just add 600W or 2.4A to the max usage of full tilt stovetop and oven in bake mode for 10100W or 40.4A. Now that would likely trip the 40A breaker especially if the oven temp is turned up to bake the dinner rolls. Adding 600W or 2.4A overall would put it at 13.1kW or 13100W or 52.4A max rating requiring an increase to a 60A branch circuit. No wonder 100A service has become the minimum and 200A the common for residential service.

Also consider an additional 600W or 2.4A to the other circuit devices such as the oven thermostat, selector switch, or timed bake controls on the analog clock, and the wiring.

The selector switch would need to handle 6000W or 24A instead of 5400W or 21.6A, I do not know what it is rated at, each contact is probably able to handle it's respective current but the combination may overload the switch. In other words the selector switch may never fail due to the additional load unless the preheat selection is made. Even if it would be fine, the age would dictate a replacement selector switch for increasing the load.

The timed bake analog clock controls only come into play on my unit when the selector is set for timed bake, but if the selector is changed for a unit without a timed bake selection, then either timed bake feature disappears or it becomes always an option on the bake selection. Hint, if only a 300W replacement is the only option, then say goodbye to the timed bake function. The contacts in the timed bake controls of the analog clock are likely to give issues under constant use for regular baking, since they were designed for occasional use for time bake. We have only tried timed bake a couple of times and would not miss the feature. On the other hand if your old stove did not have a separate timed bake selection, then the controls were designed for constant use and may be up to the additional load, but they have been in constant use for so many years that they may not have all the capacity they had when new. If your old stove doesn't even have a timed bake function, nevermind.

The oven thermostat on an old stove should be replaced if a bake element is upgraded from 2500W to 3000W. First, it may not be rated for the higher wattage. Second, even if it is it may be worn to the point that it no longer can handle the additional wattage. The universal replacements generally are made for the more now common higher wattage bake element.

Finally, you have to consider the wiring both the house and internal stove wiring. Assuming the current branch circuit is 50A. If the distance between the stove and the panel that serves it is a long distance maybe greater than 50 or 100 ft you may need to upgrade from 6 to 4 gauge wire on the circuit even if the increase does not put you over the 50A breaker or outlet or pigtail rating, all wiring has resistance which increases with length. If the maximum used amperage could be more than 50A then and upgrade to the breaker, outlet, and pigtail are in order. 6 gauge copper wire is right on the border of 50-60A depending on what type of wire was used in the first place, it may need upgraded. I have not even considered that in the era of the two stoves in question, aluminum house wiring is a distinct possibility, it must be replaced. Aluminum wiring requires a bigger safety margin than was originally allowed when it was first approved, and we are talking about pushing closer to the copper safety margin with these figures, certainly we would be exceeding the aluminum safety margin. Some insurance companies do not even cover aluminum internally wired houses even though most modern wiring terminals are UL dual rated for both AL and CU. The stove's internal wiring may not have been sized to handle the additional load a bake element upgrade would bring. Looking at the wiring diagram for my stove, I see that both upper and lower oven elements share a 14 guage wire (maximum size used in the whole unit) all the way back to the L1 terminal through the selector switch with a connection in between. This being special high temperature rated wire and inside a UL listed appliance, the NEC wire sizing does not apply. But without ready access to the appropriate wire sizing information for this application, I would hazard a guess that going from 5400W or 21.6A to 6000W or 24A when preheat mode is selected, the wire may not be big enough. I may not be able to just upgrade the wire either because it goes through the selector switch. I may end up with no preheat feature, a single element preheat, or dual element preheat with some new upgraded wire and selector switch.

OK, so I'll admit it can be safe to replace a 2500W bake element with a 3000W, but it is not as simple as just replacing the element.

Reply to
George Scott Hollingsworth

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