Just bought a house. Built in 1970. The electrical service is 150amps. Not many breakers, basically oven, central air, upstairs, downstairs and 1 other one.

If I turn a hair dryer on, the light in the bathroom dims. I haven't notice dimming if the furnace, refrigerator or central air kicks on.

I don't really plan on adding anything else electrical at this time.

So should I upgrade the service? Is this antiquated where it would matter really soon?
Or should I just leave well enough alone and worry about other stuff.

Thanks for any advice.

Tom

Dimming is not a service change issue, it's an electrical issue that primarily has to do with loose connections, wrong sized wire or wrong fuse.

It can be caused by aluminium wiring, etc. If it occurs on some outlets in the house, it could be a loose connection at the main. It could be a defective breaker.

A "service change" could fix the problem, but it isn't the problem.

You can feeel the temperature of the exterior of the breakers as a quick check. It would be helpful if you knew if you had aluminum wiring.

Now I am scared. Loose wire at the breaker box? Or is a wall somewhere?

It looks to me like the house was originally wired with cream colored wire with a fabric type of coating. My experience with it is when I was putting the new dishwasher in, the casing was very brittle. The new outlets and the AC service has been wired with white romex I guess.

By code, it cannot be in a wall. Connections must be in an accessible junction box somewhere. They cannot be covered up.

There are testers such as this one, which can help locate such faults:

IDEAL INDUSTRIES, INC. - SureTest® Circuit Analyzers

Thermal imaging can easily locate hot spots in a panel.

Wire locating tools can help find the path of a wire.

It's very possible that an electrical company does not possess these tools, but they do exist.

There are even tools where you can plug in multiple transmitters to identify outlets.

A low tech approach involves finding the circuit or circuits and what outlets are on this circuit, then using a breaker finder or AC detection probe to get an idea of the path.

Contacts can be verified with an sensitive AC voltmeter and thermometers can read temperature. You can examine all of the outlets along the path.

Nonetheless, you should have it looked at.

the only problem I see is the bathroom light is on the same circuit as the outlet, that serves the hair dryer. What is the wattage of the hair dryer? You may be surprised to find anywhere from 1500 watt to 1800 watt, or 10 to 15 amps.

This load can cause the lights to dim, due to the size wire and possible distance, and I would not be surprised to find the voltage at the service to be a bit low, due to loose connections at any or all points from the utility, meter, panel, breakers, and splices in the circuit.

This is exactly why the Code has for a while require a 20 amp dedicated circuit to bathroom outlets only.

Considering the age of the home, and who knows who did what how in the home since 1970, may be worthwhile to have the system inspected for possible problems.

All the test instruments that Kiss mentions do exist, I have all of those plus more. Never added it up,probably in the range of $200K. But we do this testing on a large scale, for any industry.

Some smaller contractors now have even the thermal imagers now as the prices have come down, and they are beginning to see the advantage of having this test equipment, or at least some.

Probably good advice to put out there is to ask any contractor what they have at their disposal to help troubleshot problems. The one man older shop may use a homemade test lamp. He will be there for hours, and still miss problems.

Well established firms may have the 42 circuit tracers, power analyzers, even infrared detectors. The more quantity and quality of instruments a contractor has, the quicker all the problems will be found. Of course, this assumes techs know how to use them.

The one man shop may charge $40.00 an hour, and be there for hours, with missing something.

I may charge $100.. 00, but usually find routine problems in less than an one to two hours.

There are some problems that just don't want to be found. Even if I had who knows what instrument would not have helped me with one problem. Huge eyelet machine, looks like a see through big diesel motor, punching out stamped metal objects, in the old day when we actually made something here.

Would run for 1 min or two hours, stop for no apparent reason, and be able to start immediately. Any one that knows relay logic will know that is a needle in a haystack to find. After working on this testing tracing checking for 6.5 hours, I had to sit to sip some coffee and have a smoke. Watching the punches is mesmerizing, but off in the corner of my eye, I see a exposed relay, I had every box opened, wires hanging out everywhere. The relay contacts were bouncing to the rhythm of the punches. At random the contacts would open enough to break the E-Stop circuit. Hit the start button and it was always ready to go.

So you never know.




You just need everything checked over, maybe a few new circuits, since the loads have increased in size and quantity, and maybe even a new service due to age and close to capacity.