Hello All,
Here’s the situation:
I recently bought a 1952 vintage Unisaw and planer. Both are 220V single phase. Both ran when I tested them at the seller’s place before loading up and coming home.
The only 220V drop in our house is in the laundry room, so I bought 50′ of 10/3 cord and put a 30A plug on one end and a 50A socket on the other end (to match the 50A plugs I put on the Unisaw and planer). The reason for the 50A socket/plugs on the tool end is because I have an air compressor in the gara….errrr, shop that has a 50A plug. Anyways, when I plug the Unisaw or planer in and hit the start switch, it just clicks like a car with a low battery and won’t start. I know the 50′ of cord is good, because when I plug the air compressor in, it runs fine. The only thing I can figure is that the 50A plugs on the Unisaw and planer are causing the problem – that confuses me though because I don’t understand why that would be the case.
Any ideas what’s going on?
Thanks in advance for any help – I’d really like to get this good old iron going!
Regards, Ethan
Replies
Ethan,
What type of starter switch do you have on that saw? Sounda like you have a voltage drop fromthat 50 foot of wire-is it thick enough for the job also?
I also have an old Unisaw with the brush type motor which draws 11 amps on full load. If your starter switch has voltage drop protector it will not start.
This is the sort of thing that is best sorted by an electrician who has the means to test amps draw etc, and make sure that your wiring is up to the job. You may get it to run, but if things are not up to spec you may find the motor over heats and dies-better to be safe than sorry.
Ethan,
Mook is right - you are getting a big voltage drop because of the length of the cord. Get a qualified electrician to sort it out. You won't regret paying for it in the long run.
DR
Sounds like you've connected one hot leg and the neutral (or possibly the ground, if the dryer connection has 4 blades), so the saw is only getting one-half of it's design voltage. If that's the case, the starter is doing what it's supposed to do - protect against undervoltage, among other things.
100A through that 10 gauge cord at 240V will only result in about 5% voltage drop, by the way. That bullet motor won't draw 100A at startup.
Be seeing you...
Double-check how you wired up the connectors. Considering the length of your extension cord and its size, you shouldn't be having any voltage drop problems.
I concur with the last two messages, something in the system is wired wrong.
I'd start by looking at the wiring at the machine junction boxes, you'll probably find a hot and neutral mix up. Alternately you have mixed up the hot and neutral in the wiring of the cord, with a matching reversal of the wiring on your compressor, so that the pair still work together.
John W.
Edited 7/28/2005 10:46 am ET by JohnW
Ethan, It is hard to imagine that is from voltage drop. 10/3 is plenty big enough to supply a 3 hp motor over 50'. In fact 50' is not all that uncommon of a distance for a machine to the panel. Of course we don't know the distance from the dryer to the panel. I think you should first check your wireing. Dryer plugs have 2 hots (black and red or 2 blacks), a common (white) and the newer ones also have a ground (bare copper or green). Your saw only needs the two "hot" lines, NO COMMON. The white common wire should be completely omited. Instead of 10/3 (with ground) you only need 10/2 (with ground). If you conected the white wire to common and then some how connected that to the saw the saw could be getting 110 volts. That would cause the clicking. Voltage drop usually causes breakers to trip under load or hot motors, for the voltage to drop that much would be unlikely.
good luck,
Mike
Ethan,
Best ever advice is to get a qualified Electrician to help you out.
I'm hesitant to give advice, as this can get dangerous, but here goes....
Best is to buy an el cheapo multi-meter (HD $15) and measure inside the starter, I'm sure you will find that you connected a live and neutral, giving only 120v. The reason your compressor is running, is because the wiring from the compressor plug is different.
In general, only in the USA, will you find a dryer supplied with three wires, using both 120v and 240v in the same appliance, with the dryer grounded independently from the circuit. It is not a good idea to use this three wire circuit for other machines running 240v, as you may get a backfeed on the wire, used for neutral on your dryer, as you don't have a dedicated ground.
Thanks everyone for the great responses!Me wire it wrong??....you must be jesting! LOL What, electricians get paid so much because this stuff is actually complicated??????Yeah, my electrical knowledge is limited. I think the call to an electrician is a very sound suggestion.For self-education's sake, I'd like to figure out what I did wrong (other than mess with it myself, right?), so I'll pull the plugs apart and see if I messed up the connectors. Who woulda thunk that 220 could be anything but 220, eh? Thanks again for all your help - Regards, Ethan
Ethan,
Sorry, I keep forgetting that American electrics are a lot different to what I am used to: Willie's last paragraph says it all.
Let us know what the electrician says, please.
P.S- American electrics sound like the stuff of night mares <G>
American electrics are a lot different to what I am used toYa bet.. We invented the Electric Chair.. A little brass tag on the back of the chair is engraved with "You Can Be Sure If It's Westinghouse"
That's as bad as the OSHA approved suicide kits for the CIA. LOL
A bad day woodworking is better than a good day working -- yes, I'm retired!
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