electric outlet for window AC question

WTF do you mean by "no juction boxes?"

What IS a "junction box" according to PA these days?

From: snipped-for-privacy@ipal.net

On Thu, 23 Jun 2005 23:29:20 GMT indago wrote: I've been thinking of setting up a whole "code comments" forum board. It would be oriented to issues about complying with, or changing, the electrical code, and targeted to electricians, engineers, and others with an interest. It wouldn't be a DIY forum.

| Here is a place on the web with a forum:

I might have to try that one out with this 15 vs. 20 amp outlet issue and see what they say. I had seen the Mike Holt site before, but had not found a forum there. Thanks for the link.

--------------------------

I like Mike Holts website I think i saw him once in the Javits Center Electrical Conference he's pretty cool., like Mickey Mouse };-) His forum is nice and clean cut and the rest is on the money, try it out Phil it can't hurt.

I also have a few contacts with Electricians Web and others from that show... well, se la vi.... =AEoy

On Sat, 25 Jun 2005 03:18:39 GMT indago wrote: | 050624 1054 - snipped-for-privacy@ipal.net posted: | |> On Thu, 23 Jun 2005 23:40:42 GMT indago wrote: |> |> | Plus the fact that a lamp cord has a tough enough time tripping out a 15 amp |> | breaker, let alone raising the ante to 20 amps. I heard a rumor that an |> | Ohio town is demanding that general outlets in living rooms, bedrooms, and |> | such be on 15 amp circuits. |> |> What town is that? | | Oops! Not Ohio; Pennsylvania. Here is a posting from snipped-for-privacy@echoes.net: | | Beeper | | Pa. code is now saying 15 amp circuits to all rooms. Receptacles and lights | for that room on the same circuit, direct feed. No junction boxes. | Exceptions are kitchens and dining rooms. They can be 20 amp, but no | junction boxes. The best our electrical shop can figure is they are trying | to do away with extension cord problems for one. Most extension cords are 15 | amp. Before, people would buy an extension, plug it into a 20 amp receptacle | and octopus everything into it. FIRE in the making. Now on a 15 amp breaker, | so it trips before fire. Junction boxes??? No extra connections that can | become loose? Don't make it easy for the not so knowledgable DIYer?? If you | don't know your wire size, use a 15 amp receptacle. Unless an old home, the | circuits are probably not pushed to the amp limit anyway.

This in a state that does not license electricians?

I do agree with the no junction box thing. There are many in this newsgroup and some forums that say there is nothing wrong with junctions done right. The thing is, even ones done right eventually become not-so-right a lot sooner than insulation breaks down. OTOH, there are some cases where you just have to have a junction. But, a good terminal block can make it safe at some cost.

Where do these numbers come from? 15 amp wire cannot blow a

20 amp breaker? Nonsense. From Automatic Electric, the continuous current for fusing a copper 18 AWG wire is 82.9 amps. Therefore an 18 AWG wire can carry more than 82 intermittent amps - for the milliseconds necessary to trip a breaker. 15 amp receptacles must installed in those rooms. Idea being a six foot power cord on any appliance would always be long enough to connect to a wall receptacle. Those 15 amp receptacles can be powered by 20 amp circuits.

But again, how reliable is the source when short term amperage for an 18 AWG zip cord is more than sufficient to safety trip a 20 amp breaker. The important parameter is time. Those 'more than 20 amps' must exist only for a short period. 18 AWG wire is more than sufficient to trip a 20 amp breaker during a short 'short circuit'.

It actually takes a lot longer than one might guess to trip a breaker (or fuse). Most circuit breakers have a thermal trip element, which is like a fuse with a time delay - it won't trip, for example, on a motor start. For Sqare D, 80 amps on 20 amp breaker has a minimum clearing time of 6 seconds. Above 200 amps the maximum clearing time is 1 cycle.

Bud--

On Tue, 28 Jun 2005 11:24:55 -0500 Bud wrote: | w_tom wrote: |> indago wrote: |> |> |> Where do these numbers come from? 15 amp wire cannot blow a |> 20 amp breaker? Nonsense. From Automatic Electric, the |> continuous current for fusing a copper 18 AWG wire is 82.9 |> amps. Therefore an 18 AWG wire can carry more than 82 |> intermittent amps - for the milliseconds necessary to trip a |> breaker. |> | | It actually takes a lot longer than one might guess to trip a breaker | (or fuse). Most circuit breakers have a thermal trip element, which is | like a fuse with a time delay - it won't trip, for example, on a motor | start. For Sqare D, 80 amps on 20 amp breaker has a minimum clearing | time of 6 seconds. Above 200 amps the maximum clearing time is 1 cycle.

This is a true issue that AFCI breakers were, in part, intended to deal with since arc faults often have sufficient impedance to fail to trip the magnetic element. If you wait for the thermal element to trip, the arc is likely to have ignited a fire. And that can be in less than a second. Supposedly, an AFCI breaker will discriminate between an arc fault at

70 amps (trip in a fraction of a cycle) and a motor start at 70 amps (as long as the motor doesn't have brush arcing issues).

You may be interested in this - from the Product Safety Technical Committee of the IEEE EMC Society:

In North America, wire sizes for power cords, including extension cords, are selected to always be capable of blowing the 15 or

20 amp building fuse in the event of a steady-state short-circuit at the end of the power cord.

The power cord wire size together with its insulation rating must have a sufficiently low impedance to withstand the overheating of the short-circuit until the 20-amp circuit breaker clears the circuit. (Cord-connected electrical heating appliances often have high temperature insulation on their power cords to account for steady-state high current conditions.

To meet this criterion, the minimum wire size for flexible cords is AWG 18, except for specific applications, in which case there are extensive insulation robustness tests designed to preclude insulation failure. Ampacity ratings of cords and cordsets are given in UL 817, Table 90. These ratings are for normal conditions.