Need to check if my electric clothes dryer is getting power. I have a two wire circuit tester that I use for 120v to check for power. Can I use this for a 240v line and more importantly, which two contacts. It is a threw prong outlet.
Testing a 240 Line
- Thread starter Theruse
- Start date
mike93lx
ALLIANCE MEMBER
Very likely the tester is rated for 300 or 600v. Post a pic or model number. It should also say on it.
A pic of the plug would help too. Worst case if you go hit to ground, you'll get 120v, but it won't hurt anything.
A pic of the plug would help too. Worst case if you go hit to ground, you'll get 120v, but it won't hurt anything.
PelicanPines
ALLIANCE MEMBER
You can test each hot leg against the ground... if they each got 120... added together they will be 240
So, you need to test the two hot legs separately...
So, you need to test the two hot legs separately...
mike93lx
ALLIANCE MEMBER
Need? Only if the tester is 120v only. Otherwise just go hot to hot to see 240v
Mike,
When you say it won't hurt anything, I hope that includes me! I will test one flat angled blade to the center ground to check for 120v and do the same for the other angled blade to the ground. At work now, so will check this evening. Thanks again.
PelicanPines
ALLIANCE MEMBER
Only if it can tell you it's 240... if one leg is not hot... it will still buzz or light... correct results depend on the tester... My way works no matter what
jayoldschool
Well-known member
You don't have a DVOM? You need to get one... Set it to 300V, probes in both sides. A cheap HF one will work fine.
pattenp
Well-known member
Mike,
When you say it won't hurt anything, I hope that includes me! I will test one flat angled blade to the center ground to check for 120v and do the same for the other angled blade to the ground. At work now, so will check this evening. Thanks again.
To confuse things more the outlet pictured is an ungrounded dryer outlet. Technically the "L" shaped hole is neutral. Should get 240V across the two flats and 120V between one or the other flats and the "L".
Zeke
Well-known member
Be careful doing this. If your dryer is not working it may be that the outlet is wired incorrectly. I'd turn off the power and pull it out to see what's going on, or off, as it were.
Almost all of these inexpensive testers will test 90 to 300v. Some to 250v only. Do examine and read any data on the device. Therefore, you can test across the hots.
Almost all of these inexpensive testers will test 90 to 300v. Some to 250v only. Do examine and read any data on the device. Therefore, you can test across the hots.
The 240v dryer outlet has worked fine for years. What prompted all this trouble was no power to a 120v outlet in garage. It turned out that the garage outlet was connected to a line that had a GFCI in an outlet in a spare bathroom (rarely used) at the opposite end of the house. At one point, I turned off all fuses and reset them before I found the culprit GFCI. That is when the dryer stopped working.
wyliesdiesels
Well-known member
Bad breaker?
Dryer should be dedicated.
What brand of panel do you have?
Dryer should be dedicated.
What brand of panel do you have?
PelicanPines
ALLIANCE MEMBER
If everything was always done perfectly... diagnostics would get used less...
I have personally found issues with dryers that were wired from two independent breakers... I also found a 120v outlet wired with TWO FREAKING HOTS on TWO breakers... with one of the hots CUT at the edge of the box... so I didn't know it... till I started to cut the BX... and got zapped... way back then... they didn't have surface/above wire voltage testers.
Falcon67
Well-known member
If this happened after switching off the breakers, I'd replace the breaker. They are not big $. Case in point, had a GFCI go out on the bench plug circuit 2 weeks ago. Switched off run, replaced GFCI, breaker on. What, no power. Switch off, take outlet apart again, make sure I didn't futz the wiring, breaker on - test. Power. OK, WTF. Breaker off, re-assemble box, power on - no power. WTF. Pull panel cover, test at breaker - works sometimes, sometimes not. Breaker is 6 years old. They's just things and things break.
That's my thinking is that it is a bad breaker. Only thing I did differently to cause this is turn all the circuits breakers off than on. Just to make sure it was not the dryer, I tried to reach my dryer plug to my 240v outlet in the garage used for my Bendpak lift. Unfortunately, I need three feet more.
Mike,
When you say it won't hurt anything, I hope that includes me! I will test one flat angled blade to the center ground to check for 120v and do the same for the other angled blade to the ground. At work now, so will check this evening. Thanks again.
There is no ground in the receptacle shown above, it is a non-grounding 125/250 volt rated device, so the "L" shaped slot is a neutral.
Checked it out and only one side is hot. Either I have part of the breaker not working or a wire loose. So tomorrow heading to HD for a new breaker as I suspect since this happened after I switched the breaker on and off. Thanks everyone for the tips today.
American Locomotive
Well-known member
I recently had a new-ish (~7 year old) Square-D homeline 30A double-pole breaker fail in the same manner. Breaker tripped and when I reset it, only one side came back up.
mike93lx
ALLIANCE MEMBER
make sure you get a breaker that is listed for your panel and not just one that fits. take a picture of the label in your panel and only bring the existing breaker with you if it matches the label.
wyliesdiesels
Well-known member
Right you are. I had to look it up. It is a NEMA 10-30. I guess the 240 is for the heat . They probably use 120 for the electronics. And I have no idea about the motor. That must mean they need a ground wire for the machine. I find it hard to believe they don't use a 4 wire plug to bring in a ground.
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