Hi All
I am looking for a bit of advice, having lost the electric supply to my original shop (long story) I have had to move it, luckily I have another barn I can use, only problem is the electric is taken from my house to a sub panel. When I start up the table saw I get power dips all over, although only for a short time. Is this harmful to my electric house lights, furnace, etc etc. Is there any way to hold up the supply to stop the dipping??
Thanks Sandie
The biggest worry that comes to mind is that of a loose connection at some point (s) which could arc and start a fire. You haven't had excitement at home until you've seen an electrical arc inside your home's outlets! Dimming of lights indicates a voltage drop; that means either an incorrectly sized run of wire(s) and/or some poor connections.
My advice is to get a qualified electrician to check out your electrical system BEFORE something goes up in smoke. I'm not just being an alarmist on this; this symptom is indicative of a serious problem. Don't worry about the lights; worry about an electrical fire.
dave
Sandie C wrote:
Try plugging the tablesaw directly into the outlet nearest the sub panel and running it. If it still dims the lights, then the wiring to the barn is most likely inadequate for your power needs (not really dangerous, just a nuisance). If it is possible, change the saw from 110volt to 220volt assuming you can and that you have 220 available. This will help.
If the lights don't dim, then most likely you just need a beefier extension cord. Buy a heavy duty one as short as you need it and plug it into an outlet close to the sub panel.
Frank
Most likely you are right (the sizing part). Generally, if a connection was loose then the lights wouldn't dim only momentarily, they would dim for the duration of the saw running. This is of course generally the case, YMMV.
Can you post specific numbers like saw HP, wire guage suppling the outlet (if you can tell), wire guage supplying the subpanel, distance from the main to the subpanel?
Frank
That's my take on it, too. You do need to be careful of damaging other equipment, however. Some things don't tolerate undervoltage or undercurrent too well. Many electronic products may bite the dust (one bit of the clock circuitry of my microwave oven did in a recent brown-out...this makes the clock/timer run about 17% fast and repair is about $200 because only the entire module, including front panel, is sold). You'd also want to be careful to make sure any MOTORS on the circuit don't stall as that could cause them to overheat and burn out.
The answer is simple, the fix may not be. You need more power to the shop. There are no shortcuts. Larger wire to carry more amps at a minimum, perhaps new service if very old and small. Light bulbs are probably OK, but other motors, computers, etc. can be damaged by it over the long term. Panels can overheat if the draw is too high for a time also.
It is best to have the lights and the power tools on separate circuits. Nothing more joyful than working at night, hitting the power switch on a tool and having the place go dark.
My first little Craftsman saw was OK on a 15A circuit, but my Delta 1.5 hp needs a 20A. First time I plugged it in to try, I had two of the three fluorescent fixtures go out on me and the third one dimmed. Next day I started running new wire.
It is also possible you need more power coming into the main. That determination will depend on what exists now and what power draw the rest of the circuits have. Talk to an electrician. Ed snipped-for-privacy@snet.net
Bad news. There is *no* simple solution/fix for this problem.
Depending on "how bad" the 'dip' is, then the answer is "yes, it _could_ hurt the other electrical devices.
If the 'dip' is *only* in the barn, then only things _in_ the barn would be *potentially* adversely affected.
Whichever situation, the _cause_ of the problem is that the wiring feeding
*to* the area that shows the 'dips' is too small for the load. *OR* (albiet a remote possibility -- the electric utility "supply transformer" is under- sized) There are three possible fixes for this: 1) _Don't_ run the stuff that causes the dips to occur. 2) Increase the size of the supply wiring. (or the utility transformer, *if* that is the source of the problem.) 3) Bring in a *SEPARATE*FEED* for the shop.For simple high-power-draw motorized tools, you could probably power them from a stand-alone generator of adequate size. 5kw is more than big enough for a 3hp saw.
All the responses given are correct. You are drawing lots of current and experiencing a voltage drop in your shop wiring. Obviously the current you are drawing is not sufficient to blow the Main breakers on the subpanel or main panel. I am assuming the subpanel is connected to the main breaker panel and not before the main breakers. If subpanel is connected correctly than the light dimming is probably bad wiring or undersized wire causing high resistance path hence power loss in wire. Other possibility is the Voltage entering your main panel may not be well regulated or lower than 115 - 120 Volts this is often the case in Isolated remote rural areas.
While I agree that there are other things to look at first, don't rule out a floating neutral. I had a similar problem in the house with even the washer agitation effected the lights. I wasn't going to build a new shop with this problem so I posted here and an electrician threw that out. I took some readings at the panel and was surprised - called the power company and he was dead on. They fixed it in a few hours. No more problems and now the new shop has 50amps to it and my Griz 1023SL which pulls 18a at 220 barely dims the lights at all and even when it does, it's barely a flicker at startup.
Don
Could someone explain what that is and how to test for it?
Frank, the motor draws more current when first started. When it's up to speed current draw drops markedly, thus explaining why she complains of the lights dimming momentarily. If she was running a constant high current device like a space heater, then the lights would be dimmed the entire time and that could be the result of high resistance in the wire or a flaky connection(s).
dave
Frank Ketchum wrote:
A floating neutral is a neutral that is not at ground potential but it as a higher potental. You can test for it by measuring the voltage between the safety ground connection (the bare wire) and the neutral. There should be no voltage present since they are connected in the panel. If a neutral connection is loose somewhere, it adds resistance to the neutral portion of the circuit and thus places the neutral wire at a potential other than ground when current runs through it. This situation can be extrememly dangerous and should be rectified immediatly. I don't however think that this is the case of the OP. The OP has the run of the mill undersized service troubles most likely.
You'll find out right before November 2004
Frank
I have a pair of printers that I use, one upstairs and one downstairs that both of them when used upstairs will draw down the lights when they first turn on. HP Laserjet 4's are the printers and well, they are work horses. Over 20000 pages have been through both, and I only picked them up 3 months ago and have not put any more than 300 pages since then. But every time I turn the sucker on, the lights dim in this room! THis house has wiring problems as in too many things on the same breaker, but with everything sealed including the basement, nothing is going to happen about it! I have just gotten in the habit of waiting till the freezer kicks off before I turn the printer on to not draw quite so much power at the same time.
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