Electrical 101

Electrical Questions Page 2

Grounding for Mig welder

Danielle wrote: I'm actually reading your website for fun because I find it very interesting & informative. I was wondering though how the grounding works as far as using a mig welder & when they clamp to the table as the "ground"? Which side is clamped to the table & which to the welder? What makes that work like it does? Thank you!

El101: Glad to hear you consider this site fun and informative. This is a very good and unique question for this site. The MIG welder electrical output uses a simple DC circuit.

This welding gun has positive (+) DC voltage. The clamp or table has negative (-) DC voltage (also known as DC ground). When you touch the welding gun to a piece of metal attached to ground, you create a controlled short circuit that will melt the metal.

DC and AC grounds are different from each other.

AC ground uses the earth as its ultimate ground.

DC ground is not connected to earth ground. DC ground is a common term for the negative (-) side of a DC circuit.

See the following DC current / flashlight diagram for a basic DC circuit.

Basic Electricity Electrical Ground

Control ceiling fan and light with two switches

Bruce wrote: Changing a single switch to a double switch to control light and fan separately. Only 3 wires at switch box-Hot/Neutral/Ground. Need 4 wires to wire double switch. Light & fan currently wired as follows: Hot/Hot/Line-in together and Neutral/Neutral/Neutral-in together and ground/ground/ground-in together Help!

El101: Here is a link to get you going. You will need an extra wire from the switch to the fan/light, or if you have NM cable, replace the 2-wire NM with 3-wire NM. This is a big job that probably should be done by an electrician.

An option would be to add a remote control to the fan and keep the wiring you have.

Ceiling Fan Switch Wiring

14 AWG wiring for lighting

Penelope wrote: Is it best to use 14-2 when wiring ceiling lights?

El101: 14 AWG is a common wiring size for lighting, and 12 AWG is common for outlets in newer dwellings. The important factor is circuit breaker amperage rating. Size 14 AWG wire uses a 15 amp breaker, size 12 AWG uses a 20 amp breaker.

If you already have a 15 amp breaker on this circuit, 14-2 or 14-3 will work. If your lighting circuit has a 20 amp breaker, you must use size 12 AWG or larger.

Push-in wire connectors

Kevin wrote: Hey guys, if I need to wire 5 different things (outlet, light bulb, etc...) and instead of using wire nuts, I want to use those push-in connectors, is that a bad idea? Also, is there any "cleaner" way to split incoming power?

El101: It is very easy to connect wires into push-in connectors, but are a major pain to disconnect. They should only be used in light fixtures. Light fixtures use 18 AWG wires which are easy to remove from push-in connectors by pulling and twisting the wires.

Never use push-in connectors in an electrical junction box. I have only encountered this once, and had to cut all the wires from the push-in connectors and re-connect them with wire nuts.

Phasing out rapid start ballasts

Michael wrote: Is it true that a lot of ballast manufacturers are going to be phasing out the Rapid Start ballast in favor of the Instant Start ballast due to the fact of newly designed LED replacement lamps.

El101: I haven't heard anything about phasing out these ballasts, but I have heard that T12 lamps will be phased out because they waste energy compared to T8 and T5. This phase out could take awhile.

Lighting controller needs to be replaced

Joan wrote: I am trying to replace a 3 way light controller on my china Hutch. It has 3 small spot lights that have high, medium & low with touch control. The unit on my china hutch says 200 watts. I can only find 150 watts. Does it matter if I replace it with 150 watts?

El101: That depends on the wattage of the spot lights. The total wattage of the 3 spot lights should not exceed the wattage of the controller. I recommend however, that the total not exceed 120 watts using a 125% derating factor.

Two lamp ballast with one lamp

Jeff wrote: can you use a 2 bulb 4 foot T 12 ballast on a single bulb 4 foot T 12 fixture and if you can what wires do you cap off?

El101: Sure you can. See the following link.

How to Replace 1 Lamp Series Ballast with 2 Lamp Series

2-wire 3-way switches

Pete wrote: How can I wire up a three-way switch with only two wire system?

There was a code change in the past that required the neutral wire to be present in each electrical box of 3 and 4-way switches. This is why a 3-wire system is used (two traveler wires and one neutral wire). The purpose of this code change is so devices that need a neutral wire can be used (dimmer, occupancy sensor, etc)

El101: If the neutral wire is not included in each box, a two wire system can be used. The two wires are used as the traveler wires in between the two 3-way switches.

Note: A 2-wire system is not up to NEC code, and a device (dimmer, etc) that needs a neutral connection can not be used.

Electrical Questions Page 1