Shop Vac skimping on electrical -

[Alchymist]

Was just browsing over my Shop Vac, (put it on a cart so it's at eye level ). Anyway, "6 Peak HP". 120 V at 11.8 amps, which is less than 2 real horses. But the clincher - 18 feet of power cord - 18 AWG! UL says 10 amp max up to 50 feet. Planned obsolescence?

 

[BillK]

18 feet of power cord -?

At least you have 18 ft ! My ancient shop vac at the shop finally gave it up a few weeks ago. Went and bought a new one. The darn power cord probably isn't 6 ft long ......... geeeeeeze I would rather have the 18 ga 18 ft one

 

[Alchymist]

Grab yourself a 25' 14 gauge extension cord and rewire!

 

[sberry]

As it says, 10 at 50, at 18 ft the 18 ga is sufficient for the time it runs. If this was a continuous load it would be another matter.

 

[Alchymist]

As it says, 10 at 50, at 18 ft the 18 ga is sufficient for the time it runs. If this was a continuous load it would be another matter.

Not to be argumentative, but it says up to 50', 2,3, or 4 conductor with 2 current carrying conductors the limit is 10 amps. True it's not a continuous load, but I have been known to vac up to 30 minutes or more, and this is something like 18% over spec. And think of someone vacuuming up flood water - think they are going to stop and let things cool? Actually the main concern is voltage drop at the motor shortening motor life.

Regardless of how you look at it, it's a cost cutting fine line. But then, it is what it is.

 

[nadogail]

The engineers who signed off on those specifications must have been trained in Detroit.

Have you ever heard of "Detroit Horsepower"?

 

[Sonorous]

I gave away my dad's Craftsman shop-vac from the 70's when I got what I thought was a top-of-the-line stainless shop vac. That thing was a beast and I still regret it to this day...

Of course the new "peak" HP ratings are bullsh*t. They measure the motors' locked-rotor inrush current (starting) rather than any actual work being done. The 11.8 amp measurement is probably the full-load amperage, which is a more accurate measure of peak power input under full torque (the heaviest possible usage).

I'm not familiar with the UL 10 amp maximum for 18 awg you mentioned, but are you sure that's not for cord sets (extension cords) and separate supply cords (printer, kettle, stereo, etc). In general, the ampacity of a cord is a function of the ambient temperature, the cord and conductor insulation temperature rating (i.e. 60/75/90/105°C), the ability of the conductors to dissipate heat, and the wire gauge.

Those generic "UL" cords may used for any number of unknown devices and are 'over'-designed with that in mind. In contrast, the cord built into your shop vac may benefit from specific thermal protection in the power supply design. The attached cord can be lab-tested and sized accordingly.

In any event, 11.8 amps may be the shop vac motor's full-load amperage, but I suspect the actual average current would be closer to 8 amps or less. I'm no where near my shop so I can't test this, but maybe someone can put a clamp meter on line splitter and measure the current of their shop vac in "idle" vs under a heavy load?

On shop vacs in general though, whether yours was $40 or $400, in my experience it's your ability to keep the filter clean that will determine the performance.

I picked up a Stihl SE62 a couple months ago for about $175 - less than my overweight Wizz-Bang-Ultra-Mega-Pro-Stainless flop vac! It's got a great filter cleaning feature that you rarely find on anything under $500, let alone for under $200. It's not as good as the fancy vibrating filters, but for the price it's by far my favourite. It's also made in Hungary rather than China. If you've ever used a Miele house vacuum it's basically the shop vac equivalent. The vacuum is not super heavy duty, but it's light enough that you don't need to kick it around either!

Regarding planned obsolescence, if you ever take apart your wheezing shop vac, you'll find a crappy brass bushing in the top of the motor assembly that's the same on the cheapest to most expensive models. You can re-oil the felt but it's only a temporary fix and a PITA to get to.

My solution is to use the crappiest little on-sale shop vac with the best filter bags I can find for the nasty stuff (drywall compound, grinding concrete). That way I always have one with a bag and don't even have to worry about swapping back and forth.

 

[Sonorous]

As it says, 10 at 50, at 18 ft the 18 ga is sufficient for the time it runs. If this was a continuous load it would be another matter.

Agreed - if the same 11.8 amp (FLA) motor was driving an angle grinder, the 18 awg cord might not work. It would be pretty difficult to work a shop vac at maximum motor torque for any length of time, and you'd probably kill the motor before significantly heating up the cord.

 

[Sonorous]

Grab yourself a 25' 14 gauge extension cord and rewire!

Shop vac cords live a hard life. If the cord was damaged I'd just cut it to 12-18" or so and put a new plug on it (with some zip-ties to secure the plug/receptacle in use). Then you can keep a 15-25' 16 awg beater extension cord with the shop vac for day to day use or use something longer (and larger awg) when you really need it. Basically what you'd find on a typical electric lawn mower.

If you wanted to go to the trouble of rewiring, I'd use 16/3 SOOW cord over anything thermoplastic (big box SJT cords) or even 14/3 SJOOW. You won't get any benefit from the 14 awg cord (only extra weight), however you will benefit from the durability of extra-hard service rated SOOW. The 16/2 SOOW I use to repair the cords on smaller grinders and sanders is actually thicker than 14/3 SJOOW that most would consider "heavy duty" cord.

I never fool with thermoplastic cords unless it's the only thing that will fit. I also 'try' not to fix things unless they're broken !

 

[woodzy]

I gave away my dad's Craftsman shop-vac from the 70's.

I have an older craftsman shop-vac I purchased 40+ years ago. It look like it should be in the dump but it is the best vac I have every used / purchased. I did replace the brushes probably 20 years ago but once it dies, it will be a sad day. I really think all the newer ones just make noise and really ***** and I'm not talking suction. I look on craigslist every now and then to try to find an older one like it for a back up but very seldom see one. One day on the way to work one was on the side of the road that was the same but it appeared to be in worst shape than mine and look like it was outside for the past 10 years.

 

[Cmreschke]

It's a late assembly and does not need to comply with nec as it has been inspected.

Look at a built in oven. I've wired some requiring a 40 amp breaker and fed with 8 aluminum, hooked my feeder to #12s from the factory.

 

[Falcon67]

I never had a problem with any shop vac cords. My 3 phase mill has 18 AWG wire coming out of the motor. That's metric 18, since it's a Chinese motor. I've only lost one vac - it was a real ShopVac, little green R2D2 thing. Worked great, had it about 10 years. Then one day it make this really desperate sound and green flames and smoke shot about a foot out the top of the unit. It died on the spot, total Hollywood ending.

 

[ratdoggy]

They really skimp on the wheels...They might as well be made of dog poop

 

[SMKS]

I picked up a Stihl SE62 a couple months ago for about $175 -

Interesting. I didn't know they had updated the Stihl models. I have the predecessor, the SE61. It was made in Hungary by Nifilsk. I'm guessing the new one is, too.

It looks like most of the specs on the new model are the same except that the new one has a larger tank.

Here's the SE 61 for anyone that cares:
http://www.stihlusa.com/products/wet-dry-vacuums/homeowner-vacuum/se61/

 

[rlitman]

As it says, 10 at 50, at 18 ft the 18 ga is sufficient for the time it runs. If this was a continuous load it would be another matter.

My guess is that it is indeed designed for continuous load. 18 gauge seems to be pretty common in vacuum cords, and 11.8A is not at all high for a vacuum.

Remember that in-wall wiring and extension cords are designed to a different spec than the cords attached to appliances. The cord on the shop vac is designed to be able to cool itself in open air.

If you look at the instruction manual for vacuums with a self-rewinding cord (and in many spring return cord reels for the same reason), you will note that they include a clause that the cord must be pulled out all the way when in use, to prevent overheating of the parallel wraps.

...Regarding planned obsolescence, if you ever take apart your wheezing shop vac, you'll find a crappy brass bushing in the top of the motor assembly that's the same on the cheapest to most expensive models. You can re-oil the felt but it's only a temporary fix and a PITA to get to...

I'm no where near my shop so I can't test this, but maybe someone can put a clamp meter on line splitter and measure the current of their shop vac in "idle" vs under a heavy load?

LOL. Somewhere in my attic is an old Electrolux Diamond Jubilee canister vacuum that started to make an awful racket when the bronze bushing had worn out. Rather than replace the motor, I turned down the rotor shaft to accept a press fit cartridge bearing, and made a bushing to fit into the oil cup (now that the felt was removed) to hold the bearing in place. That vacuum had more power and ran quieter than any other similar one I had, and I got a good number of years out of it like that until I replaced it with something with better features.

FYI, the "idle" load of a vacuum is when the suction is completely blocked (though this will burn up the motor of most vacuums, because the suction airflow is usually used to cool the motor). The peak load is when the least restriction is placed on the airflow (when the hose is removed).

 

[wssix99]

I have been known to vac up to 30 minutes or more

Can you come over and vacuum my garage?

Regardless of how you look at it, it's a cost cutting fine line. But then, it is what it is.

There's lots of other good in not over-designing stuff like this... The cost of copper has been killing us for years on a number of fronts and reducing the weight of the unit is also good. (I can't tell you how sick I am of lugging a heavy shop vac up an down ladders/stairs of the construction site!)

Remember that in-wall wiring and extension cords are designed to a different spec than the cords attached to appliances. The cord on the shop vac is designed to be able to cool itself in open air.

If you look at the instruction manual for vacuums with a self-rewinding cord (and in many spring return cord reels for the same reason), you will note that they include a clause that the cord must be pulled out all the way when in use, to prevent overheating of the parallel wraps.

Great points! I'd also think the spec's on the cord would be telling.

 

[Sonorous]

LOL. Somewhere in my attic is an old Electrolux Diamond Jubilee canister vacuum that started to make an awful racket when the bronze bushing had worn out. Rather than replace the motor, I turned down the rotor shaft to accept a press fit cartridge bearing, and made a bushing to fit into the oil cup (now that the felt was removed) to hold the bearing in place. That vacuum had more power and ran quieter than any other similar one I had, and I got a good number of years out of it like that until I replaced it with something with better features.

I had that very idea, but I have a shelf full of things to "re-engineer", most of which are actually broken, so with great restraint I cleaned/oiled it and put it all back together before I got carried away. I've been guilty of 'fixing' things till they're broken once or twice before . If I'd had a bearing on hand that was close and a project wasn't in the four-jaw, I sure would have been tempted. But I've never really liked that vac, so finding that weakpoint let me justify buying the Stihl!

I also thought about drilling a hole in the plastic top-case so I could drip some oil down, but the handle was in the way and I'd need something to seal the hole anyways. I was considering an old angled tire valve, but again decided to keep it simple and get on with cleaning up the **** I was using the vacuum for in the first place!

FYI, the "idle" load of a vacuum is when the suction is completely blocked (though this will burn up the motor of most vacuums, because the suction airflow is usually used to cool the motor). The peak load is when the least restriction is placed on the airflow (when the hose is removed).

I've heard that before (i.e. load is related to CFM) and so zero airflow means a lower load. I think I remember something in my Oneida dust collector manual. In one sense I get-it, but in another it boggles my mind. Sometimes I learn better with a bench scope and multi-meter in hand! One day...

 

[Sonorous]

Interesting. I didn't know they had updated the Stihl models. I have the predecessor, the SE61. It was made in Hungary by Nifilsk. I'm guessing the new one is, too.

It's nice to have the pics side-by-side.

I'd honestly rather it had a smaller tank and was actually comparing it to smaller models because I was sick of the overweight stainless shop vac. But it's so light that the size doesn't really bother me now that I've carried it around quite a bit.

The wheels are the only disappointing part, but I'm not complaining for the money. Again, it's light enough that it slides where it doesn't roll (rather than tipping). It helps that the inlet is low.

I think it may have been your review/posts that led me to the Stihl. I've been to our bigger Stihl dealer many times for other things, but they don't even have these out on the floor. I think they'd sell well for the price if more people knew about them. They're even the kind of thing that your wife will end up loving, so long as it's not your 25 year anniversary gift to her.

 

[Alchymist]

Of course the new "peak" HP ratings are bullsh*t. They measure the motors' locked-rotor inrush current (starting) rather than any actual work being done. The 11.8 amp measurement is probably the full-load amperage, which is a more accurate measure of peak power input under full torque (the heaviest possible usage).

In any event, 11.8 amps may be the shop vac motor's full-load amperage, but I suspect the actual average current would be closer to 8 amps or less. I'm no where near my shop so I can't test this, but maybe someone can put a clamp meter on line splitter and measure the current of their shop vac in "idle" vs under a heavy load?

Ok, real world Amprobe results:

peak startup: 18-20 amps
no hose connected: 9.2 amps
Cyclone DC attached: 8.3 amps
DC hose blocked: 6 amps

I suspect the 11.8 amp rating is with clean (or no) filter, and the current drops as the filter fills up. So, if we assume (I know) there will most of the time be a partially loaded filter, a max of perhaps 10 amps, and a real dirty filter 7 amps or so, an average of about 8.5 amps in use, or about just under 1-1/2 actual HP.

Guess the 18 AWG wire isn't in much danger!

 

[sberry]

This is a good thread. It proves out the tendency to over build by the individual and that the point is to serve the load adequately and not to build it as heavy as we can. Like many on this forum if I was to build it there would have been a 16.
As you point out the load went down, was not at peak and the user end calcs were originally for 12A which proved out to be a total rumor with a huge margin of error. Same for piping both water and error although we see more over design for air due to the fact that water is so influenced by common codes, if it was up to the diy there would be a 2 inch vs the 3/4 we have now and most point of use demand has went down, same for the drain pipe. With the advent of low flow fittings the rates have actually dropped. No more 5 gal minute flushes and even scalding due to drops on lines, cant even tell when someone flushes. I was going to upgrade some lines but changed the fixtures instead.
Same for air, in a 40 ft garage the user will never notice or recover 1/2 to 3/4 mains on a small comp and a 3/8 hose will quickly drain a 5 hp comp sandblasting. I used 7.5 yesterday thru 50 ft of 3/8 to blow a machine off and had to wait, a bigger hose would have increased the waste.
While there is a need for heavy air guns the next I would go to is smaller, so much more done in 3/8 today and even cordless which eliminate all the line loss, electric or air. With the vac there is some safety issue with the small wire but also concern with loss, not so much for economics which could prove out in a long duty cycle with longer cords but one doesn't want to lose the power, same as the air circuit, very little occurs on the circuit with a wire a size or even 2 in the case of vac but all in the whip.

 

[sberry]

So,,,,,,,,,,,,,,,,,,, the moral of the story is,,, it doesn't matter much and if it did the easiest way to cut the loss would be to cut the cord off short and use an extension cord. It would reduce loss in multiples and increase power a bit but may also reduce the life of the machine.