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DWS780 and Friends


Hugh Jass

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Hi all, new member but I've been lurking about for months. 

 

I just recently bought a DWS780 and I was looking into using a tool actuated switch to run a Ridgid 16gal vacuum to keep my cleanup to a minimum. My concerns of course are that the power requirement between the two is pretty significant with the Saw pulling 15A and the Vac drawing 12A.

 

Has anyone found a solution to this without blowing device fuses or breakers? 

 

I've found this which seems like the logical solution but it being rated right at the threshold for the saw amp I'm not sure how it would perform if the saw is working hard right at the limit.

 

http://www.amazon.com/gp/product/B0035YGLZG/ref=pd_lpo_sbs_dp_ss_2?pf_rd_p=1944687762&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B001BSL1BM&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0YCPFE6RGD5G7YQMM3TG#productDetails

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Thanks Chris.

 

Having done some more research it seems that these things are only designed for about 2-3hp motors due to starting draw, the contacts burn out quickly with big units. Since I'm looking at a 6.5hp Vac for a good CFM pull (203CFM) obviously that won't do by it's self. I understand they have work-arounds for big systems but it adds significant cost since they're designed for big shops, and all I have is a 6x12 work trailer that I keep all my goodies in.

 

Search continues. 

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I use the the dws 780 withe dewalts shop vac, have no problems tripping circuits.

 

You're referring to Dewalt's dust extractor? I was searching for a cost effective solution to not having to spend $500 for a Vac. I understand they have great CFM but aren't very practical for a mobile unit with such a very specific unit. 

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If you can get the starting times staggered you might be ok. The biggest draw on amps is when you start an electric motor. I used this vac http://www.homedepot.com/p/RIDGID-4-gal-5-Peak-HP-Portable-Pro-Vacuum-WD4050/100012506?cm_mmc=Shopping|Base&gclid=CLz9nsmt98MCFQguaQodmUEAdw&gclsrc=aw.dson a friends Dewalt miter saw and we only blew a breaker because the blade was super dull. We were cutting down a ton of scrap wood so he could bag instead of rending a dumpster. He just put a few bags out every week. I will say if you can with local rules and if it fits your situation its the most economical option.

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i run the ridgid 14gal 6.5peak hp on my Bosch GCM12SD and the suction is amazing.

breaker problems = sometimes, just depends on how i turn on the equipment, most of the time saw first, then vac. (or was it the other way around? lol - havent use it for quite a bit since my garage is a whole termite disaster  ) 

i also use a remote control for the vac.

but when im in the shop, i run the miter saw on a separate breaker....so i dont worry about it.

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Thanks for the replies guys. I contacted the manufacturer last night and he got back to me this morning with a very detailed reply:

 

 

Hi Bryan

The most inexpensive solution for your compound miter saw and shop vac would be the iVAC Switch Box, model SB-NA.  That's our original product with three outlets on the front and this is exactly what it was designed for.  

Unfortunately, your 6.5 peak HP shop vac will indeed eventually destroy the relay contacts inside any iVAC Switch.  The problem is the surge current that occurs when the vacuum starts up.  The surge current is about 5 times the steady state current specified on the label of the shop vac or in the instruction manual.  The relay in the iVAC Switch is rated at 40 amps so any shop vac with a steady state current of more than 8 amps is likely to eventually erode the relay contacts to the point where they don't work.  How long this will take depends on the actual surge current and how often you start the vacuum.  The surge current for your vacuum would be 60 amps so it might not take very long.

There are 2 solutions to this problem.  The first is to buy a smaller shop vac with a steady state current rating of 8 amps or less.  The second is to install an iVAC Contactor between the iVAC Switch and the shop vac.  The iVAC Contactor is nothing more than a large external relay that takes the load off the iVAC Switch thus ensuring its long term reliability.  I think that while this is a workable solution it is overkill and that a smaller vacuum is a better one but that is entirely up to you.  One advantage of having a contactor is that you could now have a very large dust collector working from your iVAC Switch so it is a sort of insurance to deal with future growth. 

Your 12 inch miter saw also has a surge current when it starts but it will last for a much shorter time than the one for the vacuum and it may be smaller as well because the miter saw has less inertia than the shop vac.  All circuit breakers are designed to withstand this surge current but the one in the iVAC switch acts more quickly than the breaker in your distribution panel.  This is a UL requirment for certification of the iVAC product.  As the miter saw is rated at 15 amps it has the same rating as the circuit breaker in the iVAC Switch and if the surge current is a little bit too long or bit too large then it may trip the breaker in the iVAC Switch.  I suspect that it will be OK but I can't guarantee this.  You will have to try it to be sure.  If you decide to try it please let me know how it turns out so that I will be able to advise others.  If the Switch Box won't work for you then you will have to use the iVAC Pro System.  

To use the iVAC Pro System you would need an iVAC Contactor, an iVAC Pro Switch model S11515 NA and an iVAC Pro Tool module, either the T11520NA or Pro Tool Plus, model TP-NA.  If you decide to go this route buy an iVAC Pro Switch HP package (consisting of the S11515NA and the contactor) for about US$30.00 less than buying the two pieces separately.  The cost for the package is US$112.29 and for an iVAC Pro Tool module is US$59.95.  This is still less than a $500.00 vacuum and it can be expanded as required at a fairly low cost.  

There are a couple of other things you should know.  Both the iVAC Switch Box and the iVAC Pro System have a 1.5 second delay from when you start the miter saw until the iVAC Switch starts the dust collector.  Often with a miter saw the cut can be completed before the vacuum comes on and some people find this annoying.  Also, some power tools now have electronics or a light or a laser that draws power as soon as you plug the tool in.  In some cases they draw enough power to start the vacuum even without turning on the power tool or they can keep the vacuum running after you turn the power tool off.  If your saw does this then you will want to use the iVAC Pro System and the iVAC Pro Tool Plus tool module.  The Pro Tool Plus has an adjustable current threshold that you can set to ignore the power tool's idle current and trigger the dust collector only when the power tool is running.  

As for installing the iVAC Contactor iVAC always recommends that you have an electrician do this for your own safety and to ensure adherence to your local electrical requirements but many people do it themselves.  The iVAC Contactor comes as a kit that consists of the contactor itself mounted in a standard electrical box, a pre wired trigger cable which connects to the contactor coil and plugs into the iVAC Switch and 3 clamps for mounting the wires that go into the electrical box.  You (or your electrician) has to supply the wiring from the power source to the contactor and from the contactor to the shop vac.  I have attached a rough sketch showing the basic setup for an iVAC Contactor with an iVAC Pro Switch.  The setup would be the same for an iVAC Switch Box.  Just plug the trigger cable from the iVAC Contactor into the vacuum power outlet on the Switch Box.  I have also attached an iVAC Contactor user guide which explains how to connect the contactor to the power source and the vacuum.  

I hope that helps.  If you have more questions just let me know.  

 

Best regards

Dave

 

So basically using the high powered Vac isn't an option and will destroy the internal contacts, not to mention the DWS780 is right on the limit as well. He recomends 3HP since the starting surge current is 5x normal operation, which is disappointing. Even if I find a decent enough Vac at that rating there's still the question of if the DWS780's light system will activate the vacuum by it's self. 

 

Looks like I'll have to keep it old school and go with the unit I want, run cords from different sources and hit the button manually. Boo.

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I

How long has this worked out for you? According to the rep and a few reviews I read it didn't last very long with high HP Vac's.

I actually haven't had it too long but I have just trimmed out two houses with it. Case, base, crown, and shelving of both houses: main floor with full basement. One house was hardwood floor throughout. The other had hardwood in just half main level.

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my miter saw has its own circuit breaker.

the shop vac as well - and i also control it with a fairly "cheap" $15 wireless remote ( was a 3 outlet kit from cost co )

2 of the outlets dont work anymore - i assume due to the relay contacts what the manufacturer mentioned.

so i might just buy one of the ivac switches and test it out - due to a few members who already said it works good.

i kinda dont believe everything the manufacturer tells you there, sure it can happen it will destroy the contacts, like any other electronic item. with a 6.5peak hp you def cant go wrong. even sometimes i accidently run both items on one breaker and it doesnt pop it.

even today when i build that glass rack for my truck (my new post today) i had both on one breaker. turned on the vac first, then started cutting.

like i said, buy the shop vac and the normal ivac switch or any similar switch on the market and try it out....

many members are happy with it.

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talk about a nice response from a company!       if i were you i would go for it.. you aren't gonna know until you try, right.   i've ran  vacs and miter/table saws on single circuits quite a bit (many im sure only 15A) and have only popped the breaker if the saw starts to really bog down durring a cut.   usually only happens with a table saw.

 

before i bought my extractors i used a shop vac with a craftsman auto switch, i just searched for it but it looks like they dont sell it anymore.. it was essentially the same thing as the ivac      there is also a  dgc i-socket which does the same thing and is about $15 less than the ivac

 

good luck

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Biggest issue is that sometimes I do work for big buildings, at times when a breaker does go it can be quite a pain to gain access to one of the 10 panels I have to hunt down behind locked doors. Hate the down time. 

 

I've only popped one breaker with the 780 so far and I was cutting a 2x12 PT with a 60T Dewalt "in the box" blade (which is crap for sure, it went in the bottom stack of the tool trailer after an hour). I attribute that to pushing the saw, but how many Amps could bogging a motor actually add? I doubt it's 6Amp. Maybe 3? 

 

I think for now I'll suffer though and try using my little 1HP Shop-Vac. Shockingly enough the little guy has incredible CFM for it's size I just found online (~100), the problem of course is it filling up frequently in such a small size. I'm going to try that first and see how necessary a big Vac is.

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  • 5 months later...

Thanks for the replies guys. I contacted the manufacturer last night and he got back to me this morning with a very detailed reply:

So basically using the high powered Vac isn't an option and will destroy the internal contacts, not to mention the DWS780 is right on the limit as well. He recomends 3HP since the starting surge current is 5x normal operation, which is disappointing. Even if I find a decent enough Vac at that rating there's still the question of if the DWS780's light system will activate the vacuum by it's self.

Looks like I'll have to keep it old school and go with the unit I want, run cords from different sources and hit the button manually. Boo.

I've had that IVAC bookmarked for just about two years now and haven't bought one yet for the reasons you've posted. It would be a nice unit if it was rated higher. Was hoping they would come out with an upgraded one. I also use two heavy extension cords from two different power sources and operate the vac manually and I haven't had any issues.

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