Why are 30 amp single pole breakers sold in home stores? I can't think of any correct use for them, they usually end up replacing a 15A breaker fed with #14 wire . Is there a legal use for them?

I just installed one for a RV receptacle. Other than this one I don't think I've used one in 20 years.

I've had the opportunity to use 30 amp single poles a few times. I think once was for a built in A/C + Heating unit (Think Motel style) and the other time was for a built in heater. So there are legit reasons for them, but I think you're right on when they get used the most. I've had many customers tell me they need me to put in a bigger breaker for them, thinking that's all you have to do.

the 30 amp sp breaker there are few places i can use is : rv plug , 120v waterheater, somecase large 120v air commpresser unit and few other things requied 30 amp 120v but strictly commercal/ industrail useage item

merci, marc

I think the real question should be...Why do they sell any circuit breakers in home improvement stores?

I hate to throw a wrench in the gears, but there’s some oddball stuff out there, like 1-pole 225-amp breakers [also 4-pole versions, too.] http://www.eatonelectrical.com/unsecure/cms1/DS29170F.PDF

1-pole 400A class-T pullout fuseholder with circuit-breaker dimensions—used in off-grid battery/inverter systems. http://www.boltswitch.com/131.JPG

{These are not FPE brand, although FPE did make 600-volt industrial molded-case and air-frame circuit breakers. They did not have the widely-publicized “no-trip” problem.}

In the State I live (MA) a homeowner is allowed to do their own wiring, they are supposed to pull a permit and get inspections but that's another story.

Plumbing on the other hand in this state has no such leniency, you must be licensed to do plumbing work, go figure.

As a guy that does service calls I like that HD has a lot of electric supplies, some of these stores are open 24 hrs.

We needed thousands of feet or 12 and 14 awg on a Sunday repair call, stops at couple of these stores got us what we needed.

Bob

I get through dozens of 30A (or 32A) single-pole breakers as they're very common in Britain.

The big stores are handy for when a regular supplier runs out of something and the job needs to be done in a hurry. My regular wholesaler seems to run out of a certain size cable quite regularly at the moment, so the B&Q store (similar to HD, even down to the orange color scheme) just up the road sometimes comes to the rescue.

IWIRE:

Recently I just found out about the permit process for electrical and plumbing work in New York City.

You have to be a licenced plumber or electrician in order to get a permit. The NYC Dept. of Buildings will not give permits to Joe Random, even if you know what you're doing.

Electrical work is defined as any work involving wires, repair to the wires or alteration in addition to new work and only is to be done by licenced electricians. This would technically include replacing a broken switch or outlet or hanging a new light fixture.

Ditto plumbing. Technically, changing a washer is OK. But changing a faucet or a part of the pipe is to be done by a licenced plumber. Early this year we put in a new bathroom sink (don't ask why ). That sort of job would technically have to be done by a licenced plumber.

You also have to post a copy of the permit in a visible location if your work requires a permit (eg. renovation, new construction, etc.)

This doesn't stop people from doing their own work...at their own risk -- and you can certainly buy the supplies from anyplace (wire, breakers, plumbing supplies, etc.).

Two stores (a pizzeria and a bakery) up the street from me were recently gutted and renovated.

There were no permits visible. They would normally have to be placed in the window.

An old movie theatre down the street is also being renovated. They've been doing the work for almost two or three years now. No permits are visible. Occasionally you see things being done there late at night or on the weekends.

Frankly, I wonder how licenced contractors stay in business when you've got all of this stuff going on....

Following is my opinion on all this:

Yes, there are capable DIYers and they should be allowed to get permits if they show knowledge of what they are doing.

Maybe DIY installations would be better quality if they know that it has to be inspected.

But then again, the capable DIY will do it properly no matter what, and the cheap-skates will not care becasue they won't pay the permit fee anyway.

[This message has been edited by SvenNYC (edited 10-07-2003).]

So there are legit uses them. Small water heaters, ac units, etc. All the ones I've seen are used when "upgrading" an existing breaker. Thanks for all your replies.

Just ask the guy who works in the electrical department, he'll tell you exactly how/where to install one. HAHAHAHAHAHA

But seriously, the main uses I can see are wall hand dryers (most have a 120v/20a rating), the already mentioned ac/heat units and and RV (travel trailer) receptacles(125v/30a).

Just for the sake of novelty, NEMA does list a “5-50” plug and receptacle—rated 125V/50A 2-pole 3-wire wiring devices. {However rare I guess it wouldn't be impossible to genuinely need a 50-amp 1-pole breaker.} The only use I can remember for 120V 50A circuits was for stage arc lights…”follow spots.”

Bjarney I did a job where I needed a 1 pole 50 amp breaker.

This was for the National Weather Service at Logan airport, they had a Ford Aerospace Computer (It even had a big blue Ford oval) that needed 50 amps @ 120 volts.

This was about 1983 and the computer looked to me like it was from the 1960s.

I ended up using 1 pole of a 2 pole 50 as all the supply houses claimed no such thing as a single pole 50.

Bob

I was able to find some photos of this equipment, it was a dinasour when we where relocating this equipment in 1983, I would hope they modernized since then.

Ford Terminal

Ford Equipment rack (notice the blue)

quote from the page I got these images

I wonder what "huge" would mean as compared to the PCs we are sitting at.

http://www.atarimagazines.com/v5n5/whereweathercomesfrom.html for more info if anyone finds this old equipment interesting.

Sorry for the threadjack.

Bob

For awhile brand-X was particularly adept at insisting on dedicated circuits for their photocopiers. Their means of “assurance” of this was to insist on using only (their “approved” parts-inventory house-branded) NEMA 5-30R receptacles. I think it was a guise, for peak machine load always measured well below 20 amperes. They seemed to be famous at automatic fingerpointing when any of their machines screwed up—getting flat-out snippy about demanding week-long power-quality printouts if there were any complaints about their equipment acting up.

Back when they had a bunch of sole-source lease agreements with my employer, their maintenance group was consistently most uncooperative at responding to anything that remotely appeared to be the slightest possibility of a power-quality problem. You know—the fat-headed ‘guilty-by-defective-branch-circuit until proven innocent’ mindset.




[This message has been edited by Bjarney (edited 10-08-2003).]

I've got a friend who was sent to a house where the complaint was that every time they changed the thermostat setting on their stove, the lights in the kitchen dimmed. It turned out that there was an airconditioning unit fed with a single pole 30 amp breaker which had blown one of the phases in the house. backfeeding through the element of the stove.
Whoever invented the SP 30 amp breaker....

Sparked,

Besides from the already mentioned uses, I've seen 30 and 50 Amp single poles breakers used for larger computers or UPS loads. The UPS output can either be hard wired to devices or have eight to sixteen outlets on the back. (Four outlets per 20Amp breaker)

Typically they are in data centers and have been wired correctly but I've seen plenty of smaller shops chop of the twist-lock and install a 15Amp plug on the end.

Eric

Square D lists a single pole 70 amp QO in their catalog.

They also list a single pole 100 amp in the QOU and FAL styles.