Simple electrical question....

Hey guys, think this fairly straight foward...
We are interested in installing a 20A 220V AC unit in a location where a 60A 220V welding outlet already exists. A welder will not be used there. The existing cable is rated for 60A and there is a 60A CB at the panel for this. There is also an appropriate 60A 220V outlet on the other end.
The goal is to change the CB to 20A and change the outlet to 20A 220V while using the existing wire. Is this at all possible? Seems theres going to be connection issues w/60A rated cable to a smaller 20A CB and receptacle.
Any ideas, tips, hints?
Danny
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DanF,
If the wiring, outlet and circuit breaker will handle 60 amps why would you want to change anything? The 20 amp current draw is well within their capabilities.
Dave M.
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On 24 Jul 2003, David Martel wrote:

The outlet is going to be a different configuration, it would need to be changed to match the plug used on the 20A appliance. You're right, the oversized wiring can stay, no problems there. As soon as you change the outlet, you are limiting the circuit to a safe maximum of 20A, so it is a smart move (although possibly not needed to meet code, I don't know) to downsize the breaker to 20A as well.
Think about it: If something goes wrong in the appliance and it decides to start pulling 50A, you want the breaker to protect you and shut it down. That concept doesn't hold much water when it comes to typical "convenience outlet" circuits in your home where there might be 4, 5, 6 duplex receptacles on one circuit, but in this case (one receptacle, one breaker) it makes sense. HTH.
--
TP

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I have put in smaller breakers than allowed for exactly that reason; but I have always thought about lamps with #18 plugged into 20a circuits, and wondered how many fires result from that.
I have heard in England each outlet has a breaker on it, sized to what is expected to be plugged in.
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is there to protect the structure ---- the wires inside the walls. You can plug a 7 watt nite lite into a 20 A wall outlet, or a 1500 watt heater. Either device can cause a fire if it fails or shorts, but NOT in the walls between the breaker panel and the outlet.
If the appliance needs to be protected to pass the UL safety requirements, it will be manufactured with internal fuses of some type.
Andy in Fink
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On 25 Jul 2003, Andy in Fink wrote:

Happens countless times every Chrustmas season, idiots wire a tree with 20 strings of mini-lights, 3 spotlights, 1 motorized tree top, etc, etc, all running in series through ultra light wire, the first one of which is carrying the entire load and eventually gets hot enough to start the carpeting on fire.

That's carrying it a bit too far, IMHO. For the ultra safety minded, an "extra added safety device" here in the states is a 5.99 power strip with built-in 15A breaker.

That makes all of the sense in the world for branch circuits with multiple convenience outlets, 'cause you never know what's going to be plugged in to any of them, if anything. But when you have a situation like this, where it's one breaker protecting one receptacle for an appliance, it's foolish to place the line cord in a position where it could be carrying 2x or 3x the intended current flow without tripping the breaker.
Economically speaking, if you're (original situation in this thread) saving $100-$300 from having a new piece of smaller guage wire installed, then why not spend $20 of it for the proper sized breaker?
--
TP

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Not each outlet. Each plug is fused depending on the appliance that it is powering. If I remember correctly standard sizes are 3A, 5A 10A and 13A fuses that clip inside the plug.
wrote...

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snipped-for-privacy@nowhere.com wrote:

Note that it is the plug that is fused. Not the outlet! However; as I understand it; Each circuit in a typical UK home does go back to a circuit breaker or fuse in the main panel, which in the United Kingdom is often called a CU (Consumer Unit). Other differences. 1) The voltage over there for almost all appliances is 230 volts instead of 115. So that for the same amount of wattage the current will be half of what we see in North America. For example a 1200 watt electric kettle at 230 volts requires 5.2 amps; at 115 it's 10.4 amps! The lighting circuits etc. are also 230 volts. (Well; except for 'low voltage lighting etc.'). 2) Many UK homes have their electrical outlets connected via a 'ring main'. That is to say the house wiring for a run of outlets leaves the fuse/circuit breaker panel and is wired to each outlet in turn, same as North American practice; but at the last outlet is run back to the same circuit breaker/fuse for that circuit at the main panel. In that way the electricity can flow both ways to reach any of the outlets on that 'ring'. That means twice the current can flow in that circuit; twice the current using I squared etc. = Watts, means that four times the power can be handled on a certain gauge of wire. (Or thinner wires using less copper!) Taking into consideration that their voltage is also twice that means that a lot of power and a considerable number of outlets can be provided on each ring. So much so that one whole floor of a house can be served by a single ring main circuit. Fewer circuit breakers? Smaller panels (CUs)! Each plug is fused to the size of its appliance; a very safe if more expensive? method. The quality of the plugs and sockets despite the lower amperages is very good. Also the outlets are 'shuttered'; that is the insertion of the ground pin into an outlet moves shutters away from the live and neutral pins. Very unlikely a child could stick a hair pin or something into one of those outlets; which at 230 volts is probably a good idea. 3) AFIK there is no need in UK homes for two pole/double pole circuit breakers. There are only two wires, 230 volt live, a neutral, plus an earth/ground coming into typical UK homes. In North American practice there are three wires, plus a ground coming into a typical house. 'Heavy appliances' then use 230 volts, from the two live 115 volt wires, via double pole breakers/fuses. Outlets and lights being provided with 115 via single pole breakers from one of the 115 volt live wires and neutral. IMHO the two systems are just different not necessarily one better than t'other. Corrections/amendments welcomed. Cheers. PS. It's 50 Hertz AC in Europe. Also UK light bulbs 'plug in' using a bayonet socket compared to North American Edison Screw; at 230 volts of course!
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wrote:

The whole house is wired to 240V. Unlike North America, where there are two hots and a neutral, with 240V across the hots, and 120V each to neutral, UK homes (and to an extent the rest of the 230V world), have 230V phase to neutral, and one phase entering the home (in some countries 3-phase may be fed to larger homes).

FWIW, ring circuits are fed with 2.5 mm sq wire (approx eqiuv#12AWG) , and protected by a 30A fuse or 32A MCB. Radials (outlet circuits in a straight line, where a ring would be impractical) are run with 4 sq mm wire (approx eqiuv #10AWG).

But dodgy, with people often instaling the wrong sized fuse, or not even a fuse at all.

Some circuits/appliances require a double pole break.

Actually, there is no separate ground fed from the supply in NA homes, the protective ground is derived from the supply neutral and the main service disconnect. Some UK homes derive earth the same way.
European homes also tend to have what is called an RCD, which is more or less a master GFCI that protects a number of circuits, rather than having a GFCI breaker per circuit or outlet where needed.

Edison screw is used there too.
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wrote:

shorts involve either substandard wiring, objects cutting through insulation on wires (i.e. screws, nails, or wires being strung where they shouldn't and being cut), or shorts in electronic devices. In the 11 years that I've been in the fire service I don't think I've seen a fire that resulted from a lamp shorting out.
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In alt.home.repair on Fri, 25 Jul 2003 18:00:40 GMT "TexasFireGuy"

What about mice? Any of those?

Meirman
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On Fri, 25 Jul 2003 03:50:39 GMT, "Wade Lippman"

Not quite, it is each plug, and it is a fuse.
See http://www.tlc-direct.co.uk/Book/6.3.1.htm
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Wade Lippman ( snipped-for-privacy@frontiernet.net) said...

As another poster mentioned, the breaker is there to protect the permanent part of the system.
However, how much current a given wire size can take is dependent on a number of factors, such as temperature ratings. The part of the code that says "AWG14 for 15 A" or "AWG12 for 20 A" (speaking of copper here) is not the same part of the code that dictates the rules for things like power cords for lamps.
Case in point: I will be installing a 3600 Watt built-in oven in the house we are building. It is powered by a 240V/20A circuit, which naturally has a 12/3 cable feeding it. The cable that comes out of the oven that attaches to that 12/3 cable in a junction box near the oven has 16 gauge wires!
Perfectly acceptable as this falls under a different part of the code.
--
Calvin Henry-Cotnam
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fire, should something short out in the AC unit.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
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Run a short length of 12/3 and put in a sub panel with a 20A breaker.
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Christopher A. Young
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