Omission of overload protection for resistive heating elements.

I thought you said you had never seen such a thing - although you must have.

I can see an argument, but that doesn't alter my initial comment - that (although my experience is limited) I personally cannot recall having seen such an element in a domestic oven.
 
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I thought you said you had never seen such a thing - although you must have.
This thread has got a bit confused/confusing, with 'drift' over many pages. However, if you follow the sequence of comments and responses (all the way back to page 1), you should be able to see that the thing which I "cannot recall ever having seen" is a 'bifilar' element in a domestic oven (i.e. one with just one 'business end', attached to a mounting plate, and the other end of the element 'floating about in the breeze' somewhere) - which I think is much the same as you are saying ...
I do not recall the makes and models but I have seen large domestic ovens which had bifilar elements.
... although I have certainly never knowingly seen such an animal, I can't swear that no oven elements are of such a design (it would seem daft if there were, for the very reason we are discussing).
As implied in what I have just written, I struggle to understand why they would adopt such a design (for the very reason we are discussing). 'Unnecessarily' bringing 'L' and 'N' things close together would not seem a desirable thing to do. What would be a reasonable justification?
... Engineering simplicity ? It's (generally) a lot easier to run a pair of wires to one end of an element, than it is to run one of the wires to a remote end. it's also makes mounting of the element simpler (just push it in through a punched hole and pop a couple of screws in). And for maintenance, that's now done from just one side of the ducting.
The same applies to ovens - much simpler to have both connections on the same place and one mounting plate that carries both ends of the element.
I can see an argument, but that doesn't alter my initial comment - that (although my experience is limited) I personally cannot recall having seen such an element in a domestic oven.

Kind Regards, John
 
... you should be able to see that the thing which I "cannot recall ever having seen" is a 'bifilar' element in a domestic oven (i.e. one with just one 'business end', attached to a mounting plate, and the other end of the element 'floating about in the breeze' somewhere) ...
And which is a distinction I'd missed.
So we're talking about a situation where the element has two wires within one sheath, bonded together within a "dead end", and the two ends poking out of the one sheath ? Compared with the standard linear element connected at both ends (whether it's straight or curled up), that's a very different beast and I would have thought that it would only be worth using for specific applications - for one thing, a lot harder to make.
 
And which is a distinction I'd missed.
So we're talking about a situation where the element has two wires within one sheath, bonded together within a "dead end", and the two ends poking out of the one sheath ? Compared with the standard linear element connected at both ends (whether it's straight or curled up), that's a very different beast and I would have thought that it would only be worth using for specific applications - for one thing, a lot harder to make.
It's only like Pyro and we make plenty of that.
 
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And which is a distinction I'd missed.
Indeed, and EFLI along with you, I think.
So we're talking about a situation where the element has two wires within one sheath, bonded together within a "dead end", and the two ends poking out of the one sheath ? Compared with the standard linear element connected at both ends (whether it's straight or curled up), that's a very different beast and I would have thought that it would only be worth using for specific applications - for one thing, a lot harder to make.
Exactly - so perhaps now you can understand why I wrote ...
As implied in what I have just written, I struggle to understand why they would adopt such a design (for the very reason we are discussing). .... What would be a reasonable justification?
:?: [and you now seem to be agreeing that your previous answer {when you misunderstood what we were talking about} of "Engineering simplicity" is definitely not the correct answer]

Kind Regards, John
 
How easy would it be to manufacture it such that an end-user could easily connect to the two ends of that 'pyro'?

Kind Regards, John
Admittedly it is a lesser used format, and quite rare in the duct environment I'm accustomed to, but when I have encountered it, it's not a lot different in application to the double ended versions.
That said the tendancy at failure is to change over to the more conventional double ended (If practical) due to cost and off the shelf availability at a number of providers.
 
cannot recall having seen such an element in a domestic oven.

Having built hotcupboards and Bains maries for a few years I have seen many LE shorts.
We had some seriously ****e elements in stock!
 
It's only like Pyro and we make plenty of that.
Yes. Now take that pyro, strip back the sheath to expose the cores, join the ends together - so far, simple enough. Now surround the exposed end with insulating material, apply an end cap, and seal it back up - definitely not so simple now :rolleyes: Doable, but not half as simple as simply stripping back the sheath and terminating the single core at each end.
 
Yes. Now take that pyro, strip back the sheath to expose the cores, join the ends together - so far, simple enough. Now surround the exposed end with insulating material, apply an end cap, and seal it back up - definitely not so simple now :rolleyes: Doable, but not half as simple as simply stripping back the sheath and terminating the single core at each end.
And what exactly do you think they do with the simply stripping back the sheath and terminating the single core at each end apart from strip back the sheath to expose the cores. Now surround the exposed end with insulating material, apply an end cap, and seal it back up with a termination of some sort at both ends? I don't see all that much difference in the 2 descriptions.
 
There's a lot of difference.
With single ends, you aren't insulating and enclosing the ends, you are terminating them.
With the "dead end", you have to somehow encase the entirety of the exposed cores in insulation, and apply a cap which will retain the insulation and completely encase the cores. Doable*, but not half as easy as just terminating single ends.

* With an MI element, I could see it being done by using a blind-end cap, pouring mineral powder into it, jiggling the exposed core ends into the powder, and crimping the cap down to compress the powder in a similar way to how the MI element was made by compressing and drawing out thicker tubes/bars. And possibly brazing the cap to the sheath for a complete seal depending on application.
 
There's a lot of difference.
With single ends, you aren't insulating and enclosing the ends, you are terminating them.
With the "dead end", you have to somehow encase the entirety of the exposed cores in insulation, and apply a cap which will retain the insulation and completely encase the cores. Doable*, but not half as easy as just terminating single ends.

* With an MI element, I could see it being done by using a blind-end cap, pouring mineral powder into it, jiggling the exposed core ends into the powder, and crimping the cap down to compress the powder in a similar way to how the MI element was made by compressing and drawing out thicker tubes/bars. And possibly brazing the cap to the sheath for a complete seal depending on application.

I don't know, but I suspect single ended elements are made individually with a single piece of current carrying conductor (as I assume you are saying) the free end is usually crimped and I imagine spot welded too.

The terminations generally emerge from a hard material like ceramic on both styles.
 

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