Line Fusing Amps?

[Bull]

What does this term refer to? A quick Google did not yield results.

 

[gregtwojeeps]

The size of the overcurrent protection for the circuit the device is installed on. The equipment in the pic would be o.k. to be put on a 15 amp fuse or breaker.

 

[dirtydogintex]

Mfg's recommended circuit breaker or fuse size (ampacity) for the incoming power feed.

This is larger (15A) than the running (4A) to accommodate inrush current requirements.

 

[ddawg16]

Adding to what the guys said.....

As long as your going to use a circuit breaker, you really don't have to worry about the trip curve. Most of the residential breakers have a slow enough trip curve for motors.

But....if you were going to use a fuse, you would NOT want to use a fast blow fuse. You would want a slow blow....otherwise, the in rush would blow it.

 

[Bull]

Thanks guys.

With respect to "inrush" current, is this to say that when the item (kerosene heater) is first plugged in, there is a greater amount of current required to start the motor?

 

[ddawg16]

As with any motor....it could be 10x or more of the steady state current.....especially when you start it across the line.

Some of the motors I work with are so large, there is no way you could start them across the line....you have to use a soft start or VFD. Care to guess how much a 1000hp motor pulls? A few of the ones I have used pulled 1300A at full load.

 

[Bull]

Is it possible to cause a motor to spin slowly if a cord is too small of a gauge or too long and therefore dropping the current that the motor needs to start?

I replaced the shredded cord on this old kerosene heater. I found a 13 amp outdoor rated cord. It's noticeably thinner and longer than the original cord, but since it's rated for 13 amps and the heater states 4 amps on the tag I figured I'd be okay.

Now when plugged in the motor turns very slowly, whereas before I disassembled the unit to clean and service it the motor would get up to full speed quickly.

I'm wondering if the cord might be the issue. The fan blades turn by hand, but with resistance and they don't just keep spinning if you remove your hand. Perhaps the bearings are dry or gummy, but I don't see how that would all of a sudden happen between my initial test of this thing two weeks ago and the end of its rehabilitation/reassembly last night.

 

[dirtydogintex]

Good possibility w/the longer thinner extension cord.
Goodness knows what how the mfgs calculate 'recommended/max ampacities' for the package art work.

As far as torpedo heaters go, never had probs w/ext cords except when one of the hands would use something smaller than a std 12ga x 50 footer....

 

[2ManyProjects]

Subject: Line Fusing Amps?

What does this term refer to? A quick Google did not yield results.

As others have mentioned, it is the recommended (by the device manufacturer) minimum fuse rating for the circuit feeding the device.

Is it possible to cause a motor to spin slowly if a cord is too small of a gauge or too long and therefore dropping the current that the motor needs to start?

Actually, it is the VOLTAGE drop which is the issue. And yes, it could most definitely be a problem.

I replaced the shredded cord on this old kerosene heater. I found a 13 amp outdoor rated cord. It's noticeably thinner and longer than the original cord, but since it's rated for 13 amps and the heater states 4 amps on the tag I figured I'd be okay.

Bad assumption.

First, there's no telliing what criteria that extension-cord maker used to come up with "13 Amps"; but suffice it to say that such a "rating" is not in any way meaningful in the real world. What DOES matter is the actual AWG of the wire,, vs. the run length of that wire; and notably, both "thinner" and "longer" are on the wrong side of that equation.

Now when plugged in the motor turns very slowly, whereas before I disassembled the unit to clean and service it the motor would get up to full speed quickly.

I would suggest that you discontinue using that device IMMEDIATELY, and do not fire it up again until you replace the cord with a significantly heavier one (which should be no longer than it NEEDS to be in order to do what you need it to do). Given the "15A" fusing recommendation, I would use nothing less than AWG 14; and AWG 12 would be better yet, especially if the cord (INCLUDING any extension cord you might use with it) is more than several feet long. Some folks might consider that overkill; but that's OK... Heavier is ALWAYS better than lighter, and oversizing the wire cannot hurt anything.

I'm wondering if the cord might be the issue. The fan blades turn by hand, but with resistance and they don't just keep spinning if you remove your hand. Perhaps the bearings are dry or gummy, but I don't see how that would all of a sudden happen between my initial test of this thing two weeks ago and the end of its rehabilitation/reassembly last night.

The inadequate supply voltage could/would cause the motor to draw an excessive amount of current in an attempt to "make up for" the lack of voltage, especially at start-up. That in turn induces still more voltage drop, and so on, and so on, culminating in the excessive current overheating the motor. From there, all sorts of things are possible -- none of them good.

 

[Bull]

Thanks for the detailed reply. I have some older and very heavy USA-made extension cords that are available as donors to replace this current cord. I figured a longer cord might come in handy, and the stock cord was a good 6' long anyway. I'll try a thick cord and a much shorter length and report back.

I appreciate the advice.

 

[2ManyProjects]

Thanks for the detailed reply. I have some older and very heavy USA-made extension cords that are available as donors to replace this current cord. I figured a longer cord might come in handy, and the stock cord was a good 6' long anyway.

Six feet is way too short for voltage drop to be a significant problem, unless the wire is INSANELY undersized. Even two or three times that should not be significant, as long as the cord is NOT undersized.

I'll try a thick cord and a much shorter length and report back.

Heavier wire, yes; maybe even AWG 10 if you want to be REALLY sure (tho' that is surely overkill). But don't sweat the length until/unless you get well into double digits. Put it this way: If, with a 12-15 foot cord made from good quality AWG 12 wire, the unit is still giving you problems, you have OTHER issues in play.

 

[Bull]

I found a shorter AWG 12 cord and used it to replace the smaller ( AWG 14 I believe) cord that I had installed previously.

That still didn't solve the problem, which appears to have been a stuck fan motor. But, I still do agree that the other cord was undersized and I'm glad I have replaced it.

Thanks for the help today.

 

[sberry]

Now you have some concept about how important the cord size is,,, about none for this. Now we know why the mfg didnt put a 12 on it when 16 was more than twice good enough. The only reason it had a cord as heavy as it was is that it is plugged in to a heavy circuit.

 

[G_P]

The fan should spin freely with very very little resistance. If it wont even keep spinning a little bit then it is gunked up.

Take the motor apart and give it a good cleaning and re lube or replace the bearings. Sometimes there will be little plastic plugs on each end of the motor you can pull out to add oil to the bearings/bushings. Found this out in a window shaker AC. The manual said never to dismantle the unit but when the fan jammed up I tore into it and found a huge sticker on the fan motor that said "must be oiled yearly".

 

[sberry]

The mfg of this didn't always put the smallest cord the machine needed on it, may have been an 18 but that is not legal to plug in to a circuit with a 20A breaker on it. A lot of equipment and fixtures are wired this way, cheaper and easier to add a piece of 16 wire than to add extra internal fusing. Christmas lights this way,,, tiny tiny tiny wires hooked to 120V 20,, internal fuse to protect it. Your furnace needs 4A at run, 125% of a motor, needs a wire that served 6A or so to serve the load, don't want to add internal fusing make the motor leads and all controls 16 good for 10A load but short circuit to 20A.

In the end you can feel good about a bigger better wire, again a learning curve to reflect on but its not the problem, not even part of it, although it would help a fuse blow quicker, trip a breaker faster.

 

[ishiboo]

Only GJ... 4A motor is slow when running, recommendation: 10 gauge cord.

Lawl.

 

[ishiboo]

The mfg of this didn't always put the smallest cord the machine needed on it, may have been an 18 but that is not legal to plug in to a circuit with a 20A breaker on it. A lot of equipment and fixtures are wired this way, cheaper and easier to add a piece of 16 wire than to add extra internal fusing. Christmas lights this way,,, tiny tiny tiny wires hooked to 120V 20,, internal fuse to protect it. Your furnace needs 4A at run, 125% of a motor, needs a wire that served 6A or so to serve the load, don't want to add internal fusing make the motor leads and all controls 16 good for 10A load but short circuit to 20A.

In the end you can feel good about a bigger better wire, again a learning curve to reflect on but its not the problem, not even part of it, although it would help a fuse blow quicker, trip a breaker faster.

Christmas lights/etc. are usually fused to prevent people from connecting too many together.

The wires in most appliances, power tools, etc. even if 16 or 18ga are still sufficiently large to carry a short for long enough to trip a breaker.

It is perfectly legal to plug a smaller gauge wire in an appliance/tool cord/etc. onto a larger circuit.

 

[2ManyProjects]

Now you have some concept about how important the cord size is,,, about none for this. Now we know why the mfg didnt put a 12 on it when 16 was more than twice good enough.

Not a valid or safe assumption.

The only reason it had a cord as heavy as it was is that it is plugged in to a heavy circuit.

On the contrary, that (relatively) "heavy circuit" was explicitly called for by the device manufacturer, in the form of that "fusing amps" specification. It's only prudent to believe they had their reasons for that, and that those reasons went beyond purely bureaucratic considerations.

But of course, if you "know better..."

 

[2ManyProjects]

Only GJ... 4A motor is slow when running, recommendation: 10 gauge cord.

At the time, there was an implication left hanging that this "cord" just might be exceptionally long (say, 50-100 feet, perhaps more). It turned out that wasn't the case; but had it been, voltage drop WOULD have been a serious issue.

And besides, I did say that AWG 10 would be overkill, and that if AWG 12 didn't cover things up to at least a dozen or more (many more, really) feet, he had other problems.

Christmas lights/etc. are usually fused to prevent people from connecting too many together.

The wires in most appliances, power tools, etc. even if 16 or 18ga are still sufficiently large to carry a short for long enough to trip a breaker.

It is perfectly legal to plug a smaller gauge wire in an appliance/tool cord/etc. onto a larger circuit.

Exactly correct.

I have no idea where "sberry" got his "...not legal to plug in to a circuit with a 20A breaker on it" idea; but it's wacky in the extreme.

 

[sberry]

Christmas lights/etc. are usually fused to prevent people from connecting too many together.

Yes, that would overheat the wire but its somewhat another issue. the wire is too small to be plugged in to large circuits.

An example of this is anyone get a used 4 lamp florescent fixture with small fusing going to the ballast? Well many of these come from industrial or office where in theory a 120V circuit could be to 50A,,, 30 is more common though as it simply reduces needed circuits but the internals are not rated to be connected to breakers larger than 20,,, simple to add a fuse and a service guy loves it.

 

[sberry]

The wires in most appliances, power tools, etc. even if 16 or 18ga are still sufficiently large to carry a short for long enough to trip a breaker.

It is perfectly legal to plug a smaller gauge wire in an appliance/tool cord/etc. onto a larger circuit.

Yes,, but there is a legal limit to it is my point, as was said,,, only on GJ do you come up with needing a 10 for a 4A load,,, long or not this heater will run on a hundred foot of 16, the only reason it has wire as large as it does is the short circuit rating, the load is 4.

On the contrary, that (relatively) "heavy circuit" was explicitly called for by the device manufacturer, in the form of that "fusing amps" specification. It's only prudent to believe they had their reasons for that, and that those reasons went beyond purely bureaucratic considerations.

But of course, if you "know better..."

As a matter of fact I do, this has been some generalization and not to be an exact explanation most of which is over my head anyway but,,,,,,,,,,,,,,,,,,,,,,,, I see from this and other posts we need some fundamental work on general understanding before we get to specific equipment.

 

[sberry]

We have another thread,, Kevin I believe from here found out that his comp was fundamentally wired for YEARS with a wire a size under, worked and he had no clue or reason to suspect other wise there was an issue. Everytime someone comes up with a common cord question it leads to an answer 2 code sizes above adequate, maybe more.

Maybe I read between the lines wrong but this tells me we don't understand as much as we may think. I don't know anything about electric, my stuff is real minor but can say for a fact you can actually cut a board off with a circ saw with 100 ft of small cord without smoking the motor, there is a point a couple V drop for a few seconds is way past being negligable and then some and maybe some more.

There is a lot of fusing in small appliances due to this. Got to protect the undesized wiring of the unit itself. The 200A class small mig is this way, has its own thermal protection for the internals and to protect the incoming cord,,, which is fine to serve the unit but small to be on a 50A circuit,,, actually its the duty cycle that protects it more in that case but thermal protection in motors designed this way.

 

[sberry]

I cant write on this all night and am not qualified but dawg hit it with the breaker curve. When this was made fuses werer common, the plug it came with limited its maximum ocpd and it needed a fuse large enough to allow for a start, could have used a smaller one but it would have needed tailoring specifically with a slow blow feature and we cant ask every end user to do that, so, 15A.

Here is something to consider, a 120V air comp, hard starts with run loads around 13, it comes with a 14 cord, it does not come with a number 6 or 8, or a 10 or even a 12 to handle 60A plus starts. If it did would probably trip the breaker with a cord 2 sizes too big,,, possibly... but its the theory that counts a little here in this kind of discussion.

 

[sberry]

I have friends that are electricians, several and not many of them good teachers, a couple probably gave up and a couple don't pay attn. to squat and didn't know that I didn't know. I can sympathize with 2 many here, I am not arguing with him but trying to catch what is slipping by a fine mind, probably better than my own.
I had to do my real study on the internet thru forums such as this and got a code book to follow a couple and do a few calculations before at some point over about a year some of it came to me and now I don't have to think too much to pull a cord from a box to test a 100 watt lamp, I don't need a calculator to figure out that it came off a 1000 watt heater its probably ok for the lamp.

 

[sberry]

While a general circuit needs a 20A and 12 wire there is a lot of 16 connected to 20A breakers, almost every light fixture is wired that way, a 10A wire to serve 1A load, limited by the Edison base and recommended lamp size, but several times the ampacity to serve the load,,, but has to be large enough to short circuit a 20.

 

[2ManyProjects]

Geez, man... Six posts in a row on this, each one apparently made when you had another random thought on the issue?

Yes, that would overheat the wire but its somewhat another issue. the wire is too small to be plugged in to large circuits.

You keep saying that, but it doesn't stand to reason.

An example of this is anyone get a used 4 lamp florescent fixture with small fusing going to the ballast?

Fluorescent lights are not motors. But notwithstanding that...

Well many of these come from industrial or office where in theory a 120V circuit could be to 50A,,, 30 is more common though as it simply reduces needed circuits but the internals are not rated to be connected to breakers larger than 20,,, simple to add a fuse and a service guy loves it.

Which makes our (i.e., ishiboo and myself's) point: It is responsibility of the plug-in device to provide whatever over-current protection needed by that device and/or its "captive" wiring (which would include its own power cord). Hence, beyond that, it DOES NOT MATTER how much current the circuit it's plugged into can potentially provide, as long as it is "enough".

In the instant case, that "enough" is explicitly specified as 15A; which means that EVERYTHING leading up to that device MUST be able to supply at least that much current (presumably WITHOUT inducing excessive voltage drop, etc.).

Yes,, but there is a legal limit to it is my point,

We're going to have to pretend I'm from Missouri on this one (I did live there for about a year as a kid): Show Me. I challenge you to find even one credible, verifiable reference which states that the captive wiring on a plug-in device imposes any sort of legal limit on the current capacity of the host circuit.

as was said,,, only on GJ do you come up with needing a 10 for a 4A load,,, long or not this heater will run on a hundred foot of 16, the only reason it has wire as large as it does is the short circuit rating, the load is 4.

Actually, in point of fact, given that 15A requirement (which, I agree, is PROBABLY only relevant during the start-up cycle; but still...), even AWG 10 would be inadequate to provide that full 15A (even briefly) over a 100-foot run, without inducing excessive voltage drop. Granted, it would only "miss" by a tiny fraction; but the point remains. Further, if you really did have 100 feet of AWG 16 feeding that device, excessive voltage drop would start to set in at about 3.6A. Now, what was the full-time draw spec on that motor plate again..?

I say again: That device manufacturer DID have their reasons for that 15A fuse rating.

We have another thread,, Kevin I believe from here found out that his comp was fundamentally wired for YEARS with a wire a size under, worked and he had no clue or reason to suspect other wise there was an issue. Everytime someone comes up with a common cord question it leads to an answer 2 code sizes above adequate, maybe more.

If you are trying to make the case that, as a practical matter, the OP could very likely "get away with" a somewhat lighter cord as long as the length was not allowed to get completely out of hand, I would tend to agree with you. That's just common sense; and I said as much in an earlier post. But that is beside the point. From the beginning, the question was, could a too-light and too-long cord have a detrimental effect? And the answer was, and remains, a resounding YES!

 

[sberry]

Some people are hard to help.

 

[sberry]

In the instant case, that "enough" is explicitly specified as 15A; which means that EVERYTHING leading up to that device MUST be able to supply at least that much current (presumably WITHOUT inducing excessive voltage drop, etc.).

No it doesn't, it means it calls for a fuse of 15A

Hence, beyond that, it DOES NOT MATTER how much current the circuit it's plugged into can potentially provide, as long as it is "enough".

Ah yes it does, we cannot plug this in to a 50A circuit. This appliance has no internal protection of its own, it comes with a plug that allows it to be plugged in to a max service size.

The load is 4A, we upsize for a motor to 125 % that makes it need a 5A wire, this wire is big enough to serve but too small to put on a circuit that may be breakered at 20A hence they put a cord on it heavy enough to provide short circuit interruption for 20A ocpd, this cord is heavy enough it could serve a 10A load, hence there is about a snowballs chance in hell this is going to have a voltage drop issue, the cord is 2x as good as needed and doesn't have a dam thing to do with 15A which is simply the minimum common fuse size for this so it doesn't blow every time it starts.

 

[2ManyProjects]

In the instant case, that "enough" is explicitly specified as 15A; which means that EVERYTHING leading up to that device MUST be able to supply at least that much current (presumably WITHOUT inducing excessive voltage drop, etc.).

No it doesn't, it means it calls for a fuse of 15A

Toe-May-Toe, Toe-Mah-Tow. One follows from the other.

Hence, beyond that, it DOES NOT MATTER how much current the circuit it's plugged into can potentially provide, as long as it is "enough".

Ah yes it does, we cannot plug this in to a 50A circuit.

I say again: SHOW ME.

 

[Bull]

Well, the good news is, my heater works thanks to some troubleshooting of the fan motor. And, I do feel better about the stouter cord, for whatever difference it actually makes.

So, let's all be friends again!

 

[LS6 Tommy]

Glad you got the heater working!

Tommy

 

[sberry]

It comes with a 15A plug, ho0w hard is that to comprehend. This is about like which brand of oil,,, the less someone knows about cars the more they seem to worry about oil. Here is seems we have read one page or chart about voltage drop and none of the other 800 pages in the book. This is simple amateur stuff and there is no point in showing you anything. Its obvious you think you know something you don't.

Here is the obvious part,,, he put a huge cord on it,,, didn't fix the problem,,, how is that for "show me" Don't have one clue how it works but sure its a voltage drop from the cord problem. All of these posts have this same theme.

 

[ElectroLight]

Only GJ... 4A motor is slow when running, recommendation: 10 gauge cord.

Lawl.

So true... Funny, we didn't see any GFI death warnings?

 

[2ManyProjects]

Well, the good news is, my heater works thanks to some troubleshooting of the fan motor. And, I do feel better about the stouter cord, for whatever difference it actually makes.

Glad to hear it. And fear not, the heavier cord was NOT a waste of effort. The one you were using was arguably too light for the application, regardless of length or other considerations. As such, it could have made life at least a bit more difficult for the motor -- perhaps not disastrously so, but still...

So, let's all be friends again!

It comes with a 15A plug, ho0w hard is that to comprehend.

Not difficult at all, but completely irrelevant.

This is about like which brand of oil,,, the less someone knows about cars the more they seem to worry about oil. Here is seems we have read one page or chart about voltage drop and none of the other 800 pages in the book. This is simple amateur stuff and there is no point in showing you anything. Its obvious you think you know something you don't.

Still more evasion and backpedalling noted.

Here is the obvious part,,, he put a huge cord on it,,, didn't fix the problem,,, how is that for "show me"

Reading comprehension is not your forte, is it?

Notwithstanding the fact that the advice to use a more appropriate power cord WAS well-founded at the time, we left the idea of the cord being the OP's primary operational problem a long time ago. Meanwhile, you have been REPEATEDLY asked to back up your assertion that there is some legal prohibition on running a (relatively) lightly-wired plug-in device from a circuit capable of prodigious current output. THAT is what you were asked to "Show Me". But you have consistently refused to do so, preferring instead to simply repeat the unsupported assertion, hurl baseless insults, and engage in straw-man arguments and other logical fallacies.

Don't have one clue how it works but sure its a voltage drop from the cord problem. All of these posts have this same theme.

What part of "It turned out that wasn't the case", posted TWO DAYS AGO, did you not understand?

 

[MrMark]

With very limited exceptions, e.g. motors with thermal overload, the device does not protect the supply wire. Only the breaker protects the wire. The breaker and supply wire size has nothing to do with device protection. Thus, the device has to protect itself through either internal resistance that limits its current or internal fusing, as 2Many has stated by implication.

 

[sberry]

With very limited exceptions, e.g. motors with thermal overload, the device does not protect the supply wire. Only the breaker protects the wire. The breaker and supply wire size has nothing to do with device protection. Thus, the device has to protect itself through either internal resistance that limits its current or internal fusing, as 2Many has stated by implication.

Yes it does. It does not provide thermal overload protection but short circuit within the appliance if it doesn't have its own protection..

 

[sberry]

Every once in a while we see a scheme to use a welder cord and tap some convenience outlets from it. Not to be done without adding further fuses or breakers, this is not to protect the wire but all the things you are plugging in to this are not designed to be plugged in to 50A circuits.
We can wire a common duplex with a 10, cant plug 2 factory cord items it that overheat the wire, still need a 20A breaker.

 

[sberry]

As for my comprehension,, yes I get it quite clearly,, someone read one or 2 pages they think they understand and are now an expert on th4 internet despite having limited knowledge, understanding training and experience. That part of this whole thread is quite clear as was being able to conclude the cord probably didn't have squat to do with the problem 1000 miles away and having not seen it.

I got a couple buds with some of this same thinking,,, it ran for 25 years from the factory but,,, this cant be right and it needs this and that, usually not much to do with a problem. I realize though that my experience troubleshooting a couple dozen or so units, maintaining a small fleet of fuel oil burners and fixing a couple of these types of heaters along the way doesn't mean much though.

This unit comes with a 15A plug, it doesn't list a max fuse rating due to the fact that it is equipped from the factory with an end that limits the type of circuit it can be plugged in to. A good portion of the world is wired this way. This plug defines the max circuit rating this appliance can be plugged in to.
Its so old that fuses were common when it was built and the modern breaker was not a sure bet everywhere, a device with a trip curve for motor starts. Blowing fuses as more equipment became connected was a common occurance hence the sales of way too many 30A fuses and the invention of the time delay fuse, millions of 30 were installed in general use circuits, eventually they tried to come up with a way to limit this with marginal success. You can tailor a fuse but can only build so many features in to it and someone will try to figure a way around it,,, hence the breaker.

 

[bczygan]

I love the way that a combination of miscommunication, and then testosterone fueled argument prevents de-escalation, resolution, education and clarity.

I know men are fonts of knowledge and problem solvers, but more questions and less statements could get me to the answers in a smoother fashion.

This thread makes me want to ask all the questions about how circuits are protected.

Guess it's Google time.

No real criticism...just makes me chuckle!

 

[sberry]

You got to love it,,, the thing has been running for 40 years,,, then some genius comes along and says,,, it cant possibly work that5 way,,, it needs a cord 2 or 2 sizes bigger than the one that's on there,,, like the guys that invented it or built didn't have a clue until you came along and explained it to them?