Replacing a Breaker - 25 amp to 30 amp ok?


Old 10-07-07, 11:15 AM
Thread Starter
Join Date: Aug 2007
Posts: 8
Replacing a Breaker - 25 amp to 30 amp ok?

My dryer has been tripping the breaker frequently. After warming up for about 40 minutes or so it starts tripping the breaker about every 10 minutes or even less. I thought it might be the dryer itself (it came with the house when we bought it a couple months ago) but I just borrowed a friend's extra dryer and it's again tripping the breaker. The only other possibility is that it could be either the power cord or the outlet. Since the dryer I borrowed had a 4 prong cord and my outlet is 3 prong I had to put the old cord on this dryer. But I don't see anything visibly wrong with the cord and that would seem unlikely to be the problem to me. So my thinking is that the breaker is next and if that doesn't solve the problem I'll focus on the outlet/cord.

The current breaker box is "Square D" and it appears that the breaker is a double pole 25 amp breaker. Everything I read however calls for a 30 amp double pole breaker. But I also read everyone here saying NOT to upsize a breaker. Can anyone reconcile this for me and tell me whether I should go with a 30 amp double pole or look for a 25?

I'm not sure whether I'll change the breaker or not. I'm usually game for these sorts of challenges, but my wife was reading over my shoulder when I saw that parts of the box are still live even with the main off - the words "plenty of juice to kill you quickly" were enough for her to plead that I not do this. But either way I'd like to know whether upgrading to a 30 amp is advisable or not.

Thanks in advance.
Sponsored Links
Old 10-07-07, 11:41 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 33,125
If the supply line is #10 or larger 30a is ok. 25a is unusual. Are you sure it isn't 20a?
Old 10-07-07, 11:52 AM
Thread Starter
Join Date: Aug 2007
Posts: 8
Yep, it's 25.

It has 25 stamped on the toggle so it definitely appears to be 25 amp. The oddness of it is part of the problem of course and part of the reason I'd like to go to 30a. It's easier to find 30a.

How do I know if the supply line is #10? Does that require taking apart the breaker box? Would a 25a breaker be very likely to be using a #10?

Thanks for your help.
Old 10-07-07, 01:03 PM
Join Date: Apr 2006
Location: New Bern, NC
Posts: 1,623
In order to be sure, we need know the NEMA configuration of the dryer recepticle and the wire size.

See if there are any markings on the dryer recepticle, or cord that plugs into the dryer. Something like R-12-30 or such.

Also see if you can read any marking on the cable feeding the circuit. If you can. After 20 years in the trade, I can tell a no 10 wire when I see it. You may need to find a wire guage.

If you are not absolutely sure that the wire is no 10 do not upgrade the breaker.
Old 10-07-07, 01:21 PM
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
If the cable supplying the dryer is exposed, read the writing on it. If not, measure it at either end. Or compare it to known samples of 10 gage and 12 gage wire.

Better yet, since you apparently only have three wire cable, replace the run with 10-3 with ground cable and install a proper (and safer) four wire receptacle.
Old 10-07-07, 01:37 PM
Thread Starter
Join Date: Aug 2007
Posts: 8
Well, I just realized that the plug actually has 30A 25/250v on it, so does that indicate that the wire should be fine to handle a 30A breaker? The wire isn't exposed.

The power cord has 10AWGX30 on it. Does that help at all?
Old 10-07-07, 01:56 PM
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
The power cord means nothing. Don't assume that because the receptacle is 30 amp that the wiring is. it should be, but it's possible that it isn't. Look at the wire.
Old 10-07-07, 01:58 PM
nap's Avatar
nap is offline
New Member
Join Date: May 2006
Location: north
Posts: 4,163

it means you have #10 wire for the cord but we are concerned with the premises wiring (the stuff in the wall)

30A 25/250v
this probable reads, 30A 125/250v

there may be a number on the recep like (guys, don;t shoot me if I am wrong, I don;t remember the NEMA designation for this recep)

14-30R (if 4 holes) or 10-30R (for 3 holes) or something similar in style.
Old 10-07-07, 02:28 PM
Thread Starter
Join Date: Aug 2007
Posts: 8
I was able to get to the wiring in the wall, but I still can't tell. It's a brown/tan cable if that helps anything at all. But I don't see any markings. And, nap, I don't see any of those markings on the recepticle.
Old 10-09-07, 06:31 AM
Join Date: Jun 2006
Location: usa
Posts: 274
It sounds like you may need a electrician to help you.
He (or she) could determine the wire size quickly.

Another thought......breakers do sometimes go bad (become defective). Especially if they've been tripped a few times.

What you read is correct (unless your house is wired to Canadian code).
Just because the Main is off doesn't mean that there is no shock hazard.
Some internal components are still energized and exposed.

Old 10-09-07, 09:57 AM
Join Date: Sep 2000
Location: United States
Posts: 18,497
The cable marking is probably there, but you probably haven't looked closely enough. Sometimes the marking is very faint, and sometimes just a small indentation on the jacket. Look at several feet of cable, all the way around the circumference, in good light with your reading glasses on.
Old 10-09-07, 01:16 PM
Join Date: Mar 2007
Posts: 1,341
Since the recep is accessible, why not just buy an inexpensive wire gauge and measure the wire?

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes