HF DC Switch replacement

[atgcpaul]

Couldn't get the HF DC to start today. I had a switch failure years ago on the neutral side so I wire nutted the neutrals together but left the hots switched by the original toggle. I always left it in the ON position and wired up a heavy duty extension cor with an in line switch. Well, the hot side melted. Now I'm torn. Easy thing to do is wire nut the hots together and move on. BUT what about future Paul? Might he have his hand in the impeller and unknowingly plug in the cord without the upstream switch? What would you do? Replace the switch on the DC or just use the switch extension cord?

[LCHIEN]

Couldn't get the HF DC to start today. I had a switch failure years ago on the neutral side so I wire nutted the neutrals together but left the hots switched by the original toggle. I always left it in the ON position and wired up a heavy duty extension cor with an in line switch. Well, the hot side melted. Now I'm torn. Easy thing to do is wire nut the hots together and move on. BUT what about future Paul? Might he have his hand in the impeller and unknowingly plug in the cord without the upstream switch? What would you do? Replace the switch on the DC or just use the switch extension cord?

First thing is to get a switch that will handle the load. You said you got a heavy duty extension cord with a in-line switch.
Don't forget this is a large induction motor at the max for the branch circuit current wise.
It draws 15A while running with minimal restriction.
The current surge at turn on is 60A or more - I've seen the multimeter read this and its probably not fast enough to catch the real surge current.
If your switch is rated for resistive load like lights then it may well melt when subjected to the inrush current. It may not be rated for 15A continuous. I doubt you will find an inline switch rated for 2 HP motor start on 120V.
Maybe read the fine print on the switch!
THis 14Ga cord you think would be good for 15A but a review said the in-line switch was rated for 10A. And it didn't say motor, either.
http://www.amazon.com/Ace-In-Line-Ou.../dp/B000GATS2A
A solid state relay or a good contactor might be the ticket.
Good luck.
I don't really know if the switch in the HF DC is that great a switch - I leave mine on and use a remote driving a contactor relay thats rated for 30 or 60 Amps, I can't remember.

[Relative]

I don't really know if the switch in the HF DC is that great a switch - I leave mine on and use a remote driving a contactor relay thats rated for 30 or 60 Amps, I can't remember.

And the reference to build that remote is at: http://users.sisna.com/cebula/relayboxinstructions.pdf

Mike

[capncarl]

Same here, I use a remote control that was sold as a Christmas light controller so it has very low amp capabilities. The controller drives a 30-40 amp double pole relay (contactor) that I purchased at an air conditioning supply business for $25. It will never wear out and the relay was cheaper than store bought dust Collector controllers.

[LinuxRandal]

Let me start with I remember a conversation about these switches before and am wondering it was you when the neutral failed. So my advice may sound repetitive.

First, I would consider going to Grizzly and getting a replacement from them for the HF (close enough to a clone for me).
https://d27ewrs9ow50op.cloudfront.ne...g1028z2_pl.pdf

Because your worried about plugging it in, the other option I would say is some sort of safety switch, similar to what is used on air conditioners, so the service people can work on them without you turning the outside unit on. Example from Home Depot, since I don't have good luck with links from their site:
Murray Model # GP211NU Internet # 202253160 General Duty 30-Amp 120-Volt Single-Pole Indoor Fusible Safety Switch

Either way you should have a switch to keep someone from making an OUCH.

[LCHIEN]

Can you share with us the rating of the switch that melted?

Or am I reading in a second time through that the DC switch melted even though you leave it on and use the switch in the extension cord?

CAn you define "melted" - is the plastic literally deformed and the mechanics stopped working due to excessive heat? Or is that just a figure of speech for an electrical contact failure?

[atgcpaul]

Can you share with us the rating of the switch that melted?

Or am I reading in a second time through that the DC switch melted even though you leave it on and use the switch in the extension cord?

CAn you define "melted" - is the plastic literally deformed and the mechanics stopped working due to excessive heat? Or is that just a figure of speech for an electrical contact failure?

I don't remember if I posted the first time this happened or not. The first time this happened years ago, I was using the onboard switch as the switch. That one did indeed melt. IIRC I had a HF benchtop drill press that had died so I took the switch from there and swapped it into the DC. Exact fit except the DP switch only had one contact whereas the DC, I think, had two. I'm only saying that because when I opened up the DC switch box, I found the neutrals wire nutted together and seemed like my work.

So this "new" switch also looks like the plastic around the contact has melted but less dramatically than the first time. And yes, it was left in the ON position. I'm thinking before I proceed, I should wire nut the hots together and plug in the DC to confirm it was the switch that died and not something else--there is power to the extension cord. I was at HD yesterday for something else and already picked up a 20A light switch (that's what my inline switch on the extension cord is, too) but from what you guys said, seems like I need to upgrade that.

This DC is on its own 20A circuit. Sounds like many here have their DC sharing a circuit with lights or some other piece of equipment. Why aren't breakers tripping if this thing is capable of drawing 60A on startup?

Here are pics of the melted switch. It's a little hard to see, but it seems like when it melted, the contact "sunk" in deeper and that's why I'm not getting any juice to the motor.







MODS. I attached two pics. One is showing in-line but the other is only a link. Not sure why.

[dbhost]

FWIW I would replace the defective switch. No reason to bypass a built in safety mechanism.

[LCHIEN]

your switch is getting very hot due to excessive resistance of the switch. Hot enough to melt and deform the plastic.

Consider the power dissipated at 15A by switch contact with .05, .1, .25, .5 and 1 ohm resistance:
.05 ohm P = I^2 x R = 11.25W
.1 ohm P = I^2 x R = 22.5W
.25 ohm P= 55W
.5 ohm P= 110W
1 ohm P=225W

Imagine how hot a 15W light bulb gets and then imagine if all the heat was concentrated in .1 Square inches rather than the entire surface of the light bulb.
Doesn't take much resistance to get real hot with 15A running through it!

[atgcpaul]

And the reference to build that remote is at: http://users.sisna.com/cebula/relayboxinstructions.pdf

Loring, any way you can open up that box you made and snap a picture of how all the wires are connected? I can wire my shop and house, etc, but I'm not good at following wiring diagrams.

Thanks,
Paul

[sailor55330]

I have the HF Dust Collector and had read about the potential bad switch. My solution (good or bad, I don't know) was to leave the unit in the "on" position and then wire an outlet with a wall switch to control on/off. In my mind, that would take the switch out of play. I'm the only one in the shop, so I only have to watch out for myself. Not sure if that is really any better though

[atgcpaul]

I have the HF Dust Collector and had read about the potential bad switch. My solution (good or bad, I don't know) was to leave the unit in the "on" position and then wire an outlet with a wall switch to control on/off. In my mind, that would take the switch out of play. I'm the only one in the shop, so I only have to watch out for myself. Not sure if that is really any better though

After my first switch melted, that's what I did with the second switch--left it on--and switched the DC on/off with a wall switch. This didn't prevent the replacement switch from melting. I suppose it's also just a matter of time before the lighting switch would fail, too, based on what's been reported here so I'm trying to be proactive by making the relay--or at least figuring out how to.

[LCHIEN]

Loring, any way you can open up that box you made and snap a picture of how all the wires are connected? I can wire my shop and house, etc, but I'm not good at following wiring diagrams.

Thanks,
Paul

I don't have a inside picture and it would be hard to take.

Just use a yellow highlighter and mark every wire on the schematic as you put it in.
The wires in the schematic are coded as to what needs to be a heavy wire (red) vs what needs to be a light weight control wire (blue) as per directions.

[atgcpaul]

And the reference to build that remote is at: http://users.sisna.com/cebula/relayboxinstructions.pdf

Loring, I started putting everything together tonight and just need a quick clarification on some things.

In the first schematic, the incoming hot and neutral wires from the end of the extension cord share the same connector on the contactor (A and C) as the power going to the outlet which powers the Control Device, right?

So I understand the need for the contactor because the startup amps actually exceeds the capacity of a standard switch. Do you need to put in an appropriate outlet, too? Seems like the outlet where the control device and the DC plug in to are only rated for 15A. Why isn't a beefier outlet needed here?

Thanks,
Paul

[LCHIEN]

Loring, I started putting everything together tonight and just need a quick clarification on some things.

In the first schematic, the incoming hot and neutral wires from the end of the extension cord share the same connector on the contactor (A and C) as the power going to the outlet which powers the Control Device, right?

So I understand the need for the contactor because the startup amps actually exceeds the capacity of a standard switch. Do you need to put in an appropriate outlet, too? Seems like the outlet where the control device and the DC plug in to are only rated for 15A. Why isn't a beefier outlet needed here?

Thanks,
Paul

The running amps is 15 so the outlet can handle it (although I'd recommend getting the 20A outlets that a bit beefier).
Theoutlet will not be making or breaking current, it just carries it on a connection already made.

The contactor with its beefy contacts is required because there is a large inrush of current that is being Made and Broken by the contacts as they are closing. THis is very hard because the contacts will arc esp. when the switch is opened. The repeating arcing makes the contacts crusty with corrosion and with cumulative damage they get resistive to the tune of a few ohms and get hot when they run, hot enough to melt the switch.

The outlet carries an average of 15A and does see the surge which I've measured to like 67 Amps, but the contacts are solidly made at the time, not bouncing and closing or opening. THats what saves the outlet here.

The contactor is rated for motors of 30A continuous at least and so we are stressing it with only half its design load. And we are using a device that should be designed for starting motor loads, so I presume is had beefy enough contacts to take 200-300 Amp starting surges. And finally its for Air Cond use so it should easily be able to take 100 cycles per day. I hope we are using our DCa lot less than that per day... when I use mine I let it run if I'm going to be sawing again in a few minutes. TO save wear and tear on the motor, starting caps, relays, etc. as well as clear the hoses of fine dust completely.