circuit breaker question


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Old 07-27-08, 09:26 AM
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circuit breaker question

OK
I have a stupid question regarding circuit breakers. What is the difference between a 50 amp 240V and a 50 amp 120/240 V circuit breaker? In particular, I am referring to GE THQL breakers THQL 2150 ( 50A 240V) or the THQL 2250 (50A 120/240V) I am confused when you would use one type over the other.

Secondly, is the AIC rating of a breaker important? The GE chart that I have specifies 10,000 AIC for the THQL series and 22,000 AIC of the THHQL series. Is the larger AIC always better? I am ran a 60 amp subpanel to power a hot tub and I have the THQL 50A/240V as breakers. Now I am wondering if this is the correct breaker. Should I have went with the higher AIC rating or the 120/240V breaker? I thought that all breakers were the same except for amp ratings and 120 or 240 service. Man am I confused! Help!

BTW, the subpanel is up; I am waiting for my wiring to come before I get it finished. How can I post pics so you professionals here can check my work?

For the record, I did NOT bond the ground or neutral together (thats only in the main panel), and I ordered #3 THHN wire to feed a 100 amp main subpanel box with a 60 amp FEEDER breaker out of the main panel (200A service). I doubt that I will ever pull more than 70A on the subpanel but I installed a 100A sub in the event that in the distant future I want to upgrade.

For now though, can someone clarify the breaker issure for me? Thanks a bunch!

Ben
 
  #2  
Old 07-27-08, 10:11 AM
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The AIC or ampere interruption current refers to a condition when a dead short circuit exists on the circuit. For an instant, before the breaker opens and clears the fault an extremely high current can flow. If this is high enough it can destroy the breaker and perhaps make it fail whe nit attempts to clear the fault. This maximum current is limited by the resistance of the wiring from the distant pole transformer into your home and the size of the transformer itself. For most all residences served by overhead or underground wires in a residential neighborhood a 10,000 rating is fine because the wiring limits the maximum instantaneous current to less than this.

The 65.000 rating is often required in apartment situations where the main feed serves many users and there is a very short distance to each. The transformer serving then would have a very high KVA rating and would be closely located.

I am not sure of the exact criteria to determine this but I think it is safe t say if you live in a single family home you do not need higher than 10,000. There is no problem with going to the higher rated breaker though if that makes you feel more comfortable. It just costs more.
 
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Old 07-28-08, 09:01 AM
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Originally Posted by italian_guy View Post
THQL 2150 ( 50A 240V) or the THQL 2250 (50A 120/240V) I am confused when you would use one type over the other.
I don't know what a THQL2250 is, but I do know that the THQL2150 is the correct breaker for your application.

Secondly, is the AIC rating of a breaker important?
Only in buildings other than single-family homes. The 10k rating is appropriate for single-family residential.

How can I post pics so you professionals here can check my work?
You can upload the photos to a free photo sharing site like flicker, photobucket, etc then post a url.

I ordered #3 THHN wire to feed a 100 amp main subpanel box with a 60 amp FEEDER breaker out of the main panel (200A service).
Why such oversized wire? A 60A panel is typically supplied with #6 THHN copper. Just so you know, your upsized hots will also require an upsized ground of at least #8.

I doubt that I will ever pull more than 70A
You'll never pull more than 70A with a 60A breaker on the line...

on the subpanel but I installed a 100A sub in the event that in the distant future I want to upgrade.
I see. Although there's really no upgrade since you're already there. You have a 100A panel with 100A wire, why not just get the 100A breaker?
 
  #4  
Old 07-28-08, 11:01 AM
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I might be blowing hot air, but I am guessing the 22050 (actual model number) is for high leg 3 phase or other 240 to neutral supplies, the 1250 for standard 120/208/240 or other 120 to neutral systems (such as typical residential).
 
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Old 07-28-08, 11:48 AM
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Since I posted this, I decided on a THQL 70 amp main feeder instead of the 60. I see your point about the 100 amp breaker but honestly, I doubt that Ill ever need more than 70. My goal was to allow the sub for ONLY a 50 amp hottub (coming next spring) and possibly a 20 amp branch circuit (both coming out of the sub. BTW, that 20 amp is a GFCI breaker....will be used IF I decide to run any outside receptacles or anything exposed to the weather....thats it..im not using the sub for anything else.

The sub is a GE power mark gold series..came with the 100 breaker. I wanted a main breaker rather than a main lug style because I can use the main on the sub as a disconnect should I need it.
Why such oversized wire in the sub? Dunno really..overkill maybe? All this stuff I hear about codes and inspectors failing because the wire size is not up to code....SOOO, I thought 'well lets go a little heavier than I really need...' I realize that I prob could have gotten away with #4 if my max breaker is 70 Amp but I just want a little (more expensive) peace of mind!


As far as that THQL2250 breaker type, check out the following link and scroll down to where it says Q line breaker types (on the adobe menu) and look for that model.....I really dont know the difference between the THQL2250 and the THQL 2150..
http://www.geindustrial.com/publibrary/checkout/Catalogs%20and%20Buyers%20Guides%7COEM-LOADCENTER%7Cgeneric"]http://http://www.geindustrial.com/publibra...NTER%7Cgeneric[/URL]

NOW, for the last question..I didn't hook any wires into the main panel yet because.......Im a little uneasy shoving my hands in a 200 amp box when the main is shut off......how much trouble is it to have the utility company come out and shut the power off at the meter so I can finish the wiring? I guess Im being a girl about shoving my hands in there and fishing wires into the box when i have the LIVE service wires nearby.........
Thanks for the replies so far....
Ben
 
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Old 07-28-08, 01:04 PM
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Well you are being safe and there is nothing wrong with that.

If your meter does not have a locked band around it that stops you from pulling it and just has a band with a wire locking it, you can cut it and remove the meter. Pull it straight out. C over the hole with some cardboard, so no one pokes around in there while you are working.

When you are done working in the main box - wire to sub installed and circuit breaker wired and turned off, you can reinstall the meter. At some point call your utility and tell them you had the meter out, so they can come back and re-seal it and they won't think you are stealing power!
 
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Old 07-28-08, 02:53 PM
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The electric meter is the property of the utility company and depending on the company some will prosecute you if you pull the meter. In my neck of the woods I have to deal with several utilities, one of them being Georgia Power, I was forbiden, under threat of legal action, to pull a meter that was sizzling and smoking. Had to wait almost an hour for a lineman to arrive and pull the meter. If you have a main breaker just shut it off and make your connection.
 
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Old 07-28-08, 04:19 PM
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Sometimes it is better to ask for forgiveness then to ask for permission! It has always worked for me. Besides 9 times out of 10 you never have to ask for forgiveness.

prosecute a professional, maybe but not likely, a homeowner, never happen.
 
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Old 07-29-08, 05:59 AM
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Nah, Im not going to arbitrarily cut the tiny metal clip off the meter because I dont want to be accused of theft of service from the utility co. i just hope that when I call them that they:
1) can disconnect and reconnect power in the same day
2) dont ask me if I had a permit to do the work and if it was gonna be inspected (no on both counts)
Where I live, the township is a stickler; christ you have to have a work permit to have an old car up on blocks if you are repairing it at your house!
I don't want to think what they would do to me if they found out the work i did; granted, most people do their own work. I am not a licensed electrician; not even close! I just choose to do my own work after extensive reading and research because I know it will prob. be done right. (well, as right as the info I gather from different sources!)
Thanks again for all the great replies and the continued help with my projects!
 
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Old 07-29-08, 07:32 AM
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Well do what you think is best.

If you turn off the main breaker and fashion a piece of cardboard to go around the connection for the main line coming in at the (usually) top you should be fine. If the main is off the rails coming down to serve the breakers is dead. Always check first though.

All you have to do is punch out a knockout, bring the wire in, and connect it to a breaker. If you do this work below where the service wires enter, you should be fine.

If you call the utility you may start a chain of events you don't want to happen. I don't know ehre you are. It is not the case here in PA.
 
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Old 07-29-08, 12:18 PM
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Originally Posted by italian_guy View Post
OK
I have a stupid question regarding circuit breakers. What is the difference between a 50 amp 240V and a 50 amp 120/240 V circuit breaker? In particular, I am referring to GE THQL breakers THQL 2150 ( 50A 240V) or the THQL 2250 (50A 120/240V) I am confused when you would use one type over the other.

For now though, can someone clarify the breaker issure for me? Thanks a bunch!

Ben
Ben the 120/240 V breakers are used on grounded systems and are usually called "slash-rated breakers." Very original. The 240 V breakers would be required only on un-grounded systems, which almost nobody has anymore.
 
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Old 07-29-08, 12:44 PM
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Dave
Thanks for the info. Now I really AM confused [I]
If you look at that GE chart, I posted the link to, I bought a THQL 2170 70 amp breaker..according to this chart, it falls under the 240VAC column. IF i used the THQL2270..that is the slash rated 120/240VAC breaker! From what I am understanding from your post, did I put the wrong breaker in the main box? I have a grounded system in my main panel (the neutral and ground are bonded BUT they are seperate (UN-bonded in the subpanel.....(each wire goes to seperate bars...ground to ground bar and neutral to neutral buss bar and red and black to the 100amp main.......
 
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Old 07-29-08, 01:05 PM
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Sorry I was not clear before. I meant to say I believe you could use either breaker for your situation.

If you had an ungrounded system you would have to use the 240 V and you could not use the 120/240 V breaker. I am not 100% sure on this, but I think I am right.
 
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Old 07-30-08, 08:58 AM
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Originally Posted by italian_guy View Post
1) can disconnect and reconnect power in the same day
Pretty likely. The guy may even hang around if you're quick.

2) dont ask me if I had a permit to do the work and if it was gonna be inspected (no on both counts)
This could go either way. Some utilities don't really care, and some absolutely will not reconnect until they see the tag from the inspector.

In any case, I would strongly urge you to not pull your own meter. While it may or may not be illegal it is certainly unsafe.
 
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Old 07-31-08, 01:39 AM
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Ok.,,

What I did is double check with my catalog book and I will make a quick run down on the catalog numbers



If you look at that GE chart, I posted the link to, I bought a THQL 2170 70 amp breaker..according to this chart, it falls under the 240VAC column. IF i used the THQL2270..that is the slash rated 120/240VAC breaker
the slash rated breaker is good on standard single phase system while the other one nonslashed is used on Delta system { common on 3 phase system }
( The delta system have wild leg if have 4 wire verison due the netural and wild leg is 208 volts that the reason why the straght 240 volts rated breaker is used on that appcation )

Here the real McCoy numbers

Your breaker number is THQL2170

It mean T = GE indendication number
H = 10 KA AIC rating
QL = 1" plug in
2 - two pole
1 = 120/240 volt
70 = amprage rating

The THQL is very common breaker and you can find this in big box store if they have it.

{ anything over 60 is little harder to find expect the 100's which it is common one }

Merci,Marc
 
 

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