I wired a 6000 sq ft home in a rural area about 4 years ago and since then, the homeowner has had to replace 5 dishwashers, and 4 microwaves. The dishwasher is 120v of course but the microwave is a 240v built in. We have had the POCO do a study on the incoming power, we have checked all the wiring, and nothing else in the house has been affected. Not a single flickering LED can light, no burnt up computers or TV's, or literally anything else having any problems. The POCO placed their meters on his home for about two weeks and said everything looked good. It's been a year and a half since the last appliance burned up and now all of a sudden the microwave has gone again. The microwave circuit is a straight home-run to the panel which has been checked numerous times but the homeowner is convinced that I have screwed up his wiring. How do I know that his other family members aren't microwaving forks or other metal items? Anyway, I've been doing this for 30 years and in business for myself for 20 years, and never have I seen this happen before. Any other ideas?
Is it my problem or theirs....
- Thread starter wiredit
- Start date
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Do the burn outs happen after a lightning storm? It is odd that only the dishwasher and microwave have an issue. Are there any multiwire branch circuit especially with the dishwasher?
Seven-Delta-FortyOne
Goin’ Down In Flames........
- Location
- Humboldt
- Occupation
- EC and GC
Maybe some additional info:
I don’t like to assume, but I assume it electrical issues on all these appliances that are causing the failures?
What exactly is getting checked on these circuits, or the service entrance?
Are there any SPDs installed anywhere?
I don’t like to assume, but I assume it electrical issues on all these appliances that are causing the failures?
What exactly is getting checked on these circuits, or the service entrance?
Are there any SPDs installed anywhere?
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I was just going to add that you should install some whole house surge protection.
We are in Central California and haven't really had any lightning storms since last year although we did get a light rain last week. If I recall correctly, the dishwasher and disposal is on a 12-3 home run from the panel and a 2 pole 20 amp breaker. Arc faults for these circuits weren't required at the time. The microwave is a 12-3 home run on a 20 amp 2 pole as well but it is a 240v appliance.
No SPDs yet but sounds like that is going to be next. The dishwasher/disposal circuit is a 12-3 to the panel on a 20 amp two pole breaker. The plug under the sink has the hot tab broken and all of the connections have been checked repeatedly and are always tight. There has never been a problem with the disposal and the dishwasher has been fine now for at least two years. The voltage readings are within normal range and there are no shorts between the wires. My thought is that they are getting small power surges from the POCO at certain times of the year and that these two particular appliances just don't love power surges although if the microwave went out because of one, the dishwasher seemed to handle it this time.
- Location
- Illinois
- Occupation
- retired electrician
When the power company did their checking, did thy use a "beast of burden" to verify there is no neutral problem on the line side of the meter?
texie
Senior Member
- Location
- Fort Collins, Colorado
- Occupation
- Electrician, Contractor, Inspector
You state the the microwave is 240 volt but have a 12/3 home run. This implies to me that it is actually a 120/240 appliance. There is a difference and then a loose and /or intermittent neutral could be a possibility here.
On the other hand if you have a neutral issue some where upstream of these 2 appliances it seem likely that there would be other signs such as some bright and some dim lighting issues noticed or other failures.
letgomywago
Senior Member
- Location
- Washington state and Oregon coast
- Occupation
- residential electrician
Are these always replaced with exact same model number? Or have there been different models tried?
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
If the PoCo hasn't, you can do your own "loose neutral" test with just an electric heater and a voltmeter.
In the past I have had our POCO put in a recording meter by the main service to record the sine wave.. Then they will pick it up after 6-9 months and study the results.
See if your POCO will do this.
Or I am sure resonoably priced equipment is available for you to buy and monitor the problematic circuits.
See if your POCO will do this.
Or I am sure resonoably priced equipment is available for you to buy and monitor the problematic circuits.
ptonsparky
Tom
- Occupation
- EC - retired
The 12/3s seem to be the common denominator.
I don't remember ever having to use the POCO and beast of burden to determine a neutral issue. Zbang listed the equipment.
I don't remember ever having to use the POCO and beast of burden to determine a neutral issue. Zbang listed the equipment.
Another C10
Electrical Contractor 1987 - present
- Location
- Southern Cal
- Occupation
- Electrician NEC 2020
maybe a flashing clock on the microwave.
either way explain it to the customer with a calm demeanor, so they feel confident you know your insight.