Electrical 101

Electrical Questions

Old house with no ground

Mike wrote: I have an old house built in the 1930s. The electrical outlets work fine but have two prongs. how do I change over to three prong outlets or should I stay with the two prong versions.

El101: If you stay with the two prong versions, you can't plug in a three prong plug without an adapter, losing ground fault protection.

The cheapest way to convert your outlets to three prong is to replace the outlets with GFCI's. GFCI outlets are a good substitution for not having a ground on your house's electrical system. Keep in mind that an outlet tester with a GFCI trip button will not trip a GFCI that does not have a ground connection. Pushing the test button is the only way to test a GFCI with no ground connection.

Electrical boxes in old houses tend to be pretty small and can be difficult to install a GFCI. A "slim" GFCI would fit more easily in a small electrical box.

Rewiring this house is usually crazy expensive unless there is a major renovation. You can contact a licensed electrical contractor to see if the house can be rewired at a reasonable cost.

Wrong wire colors on 3-way switch

Bob wrote: What to do in a 3-way switch when there are only 2 purple wires on brass screws on one side and 1 brown wire on opposite side or switch? There are no white, black or red wires on this switch.

El101: Looks like you have conduit instead of NM cable. The purple wires are traveler wires, and the brown wire is the common wire. See 3-Way Switch Wiring page.

Dimmable photocells

BJ wrote: Need to dim a photocell on the load side of a circuit. Is there any dimmable photocells, stem or button types?

El101: We are not aware of any dimmable photocells available on the market. You may be able to use a dimmer as the on/off switch and use a photocell to control the light. There may be compatibility issues. Try it out and let us know if it works.

Open circuit at RV park

James wrote: We keep our camper at a Campground. I just bought and plugged in a Cammco 30 amp surge protector with circuit analyzer. It shows an open circuit. What can be done? I wish to stay at the Campground but need my family to be safe.

El101: Could this "open circuit" actually be an open ground? You need to know what exactly is "open". The first thing you should to do is alert the campground office of this condition. Have them check out what the surge protector found and see if there is a problem they should address.

Combine 3-way switch with single pole

Rich wrote: is there any possible configuration to connect a 3-way switch + a 2-way switch to one light??? I encountered this situation while replacing the switches and outlets in a 1974 buddy double wide mobile home...

El101: There is no way we know that you can combine 3 or 4-way switch circuits to other switch circuits and have it work properly. You may want to try to combine both switch circuits to one 3-way or one 4-way switch circuit.

Lamps and ballast do not match

Eder wrote: Here is Eder, of Rio de Janeiro, Brazil. I need an small help, how I power on 3 lamps of 10w in ballast of 32 w ? My ballast only have 4 wires out, not see it in your pictures. Please, help me, can draw in picture attached. thanks

El101: Sorry, but you can not connect any lamps to a 32 W ballast unless they are 32 W and listed on the ballast as compatible. The lamps and ballast need to match.

I can help you match a ballast for your 10W lamps, or match lamps to be used with your 32 W ballast. Let me know which way you want to go, and send me part numbers, descriptions, or pictures of the 10 W lamps or the 32 W ballast.

Weird electrical problems

Mark wrote: My house has somehow developed a problem - radio goes off by itself, dishwasher won't turn on, skill saw runs half power-panel breakers showing every other breaker to be 90v and 140v I'm told it's very dangerous and usually an open neutral at the meter. I'm getting it fixed but how does this happen usually? Did I use too many amps?

El101: You may have a loose or open neutral on the bus bar in your electrical panel. You should hire a qualified electrician to check out this problem and maybe figure out why this is happening.

Parallel ballast wiring bad lamp

Jim wrote: in parallel ballast wiring with multiple lamps, if one of the lamp has an open circuit, which wire has the supply voltage - blue (individual) or red (common)

El101: Individual and common wires on a ballast both supply voltage to the lamps. The best way to tell if a lamp is bad with a parallel wired ballast (instant start), is to swap the unlit lamp with a known good lamp. If the good lamp lights up in the previous unlit location of the fixture, the unlit lamp is bad. If the good lamp does not light up, it is probably a bad ballast.

Variations in voltage

Dennis wrote: I have a 208V 3 ph source with neutral supply several power outlets. the trouble that I'm encountering right now circuit 1 has 102 volts only (very low) sometimes 92 volts and circuit 2 has 118 volts. If I plug a component in circuit 1 the circuit 2 voltage rise up to 210 volts and the component that plug in circuit 1 does not work and if I unplug the component the circuit 2 voltage return to normal. how can I solve this problem?

El101: Sounds like you might have an open neutral somewhere. I recommend hiring a qualified electrician to troubleshoot this problem.

Electrical Questions Page 2