What's Wrong Here?

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1

Originally Posted By: jpope
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Can anyone see the problem here?


This is the condenser disconnect. Metal box and FMC, 240 volt system.

![](upload://a13qz20oSaV8Bo7q5aGZvhQOTnz.jpeg)

I'll be out all day working. I'll check in this evening. . .

--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738

2

Originally Posted By: Joey D’Adamo
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I could be wrong… but it looks like a fuse puller is required to operate it. It doesn’t look like in an emergency it could be operated with a handle/toggle/switch/etc.


Is that it?

3

Originally Posted By: bbadger
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Well the pull out is missing for one.


Also a minor problem is the fact that there is less than 6" of conductor entering the box.

Other than that I see no problems.

--
Bob Badger
Electrical Construction & Maintenance
Moderator at ECN

4

Originally Posted By: lkage
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I agree.


You can't readily disconnect the load.

5

Originally Posted By: bbadger
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In the picture it is currently disconnected, it is missing a piece that fits in the rectangular spot between the fuses.

–
Bob Badger


Electrical Construction & Maintenance


Moderator at ECN

6

Originally Posted By: jpope
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Sorry, I pulled the disconnect to remove the cover.


Where's the neutral?

--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738

7

Originally Posted By: bbadger
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jpope wrote:
Sorry, I pulled the disconnect to remove the cover.

Where's the neutral?


Back at the panel?

No reason to bring a neutral to this unit if it is 240 volt.

--
Bob Badger
Electrical Construction & Maintenance
Moderator at ECN
8

Originally Posted By: jpope
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bbadger wrote:
No reason to bring a neutral to this unit if it is 240 volt.


I've seen these both ways. Can you explain why not?

--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738
9

Originally Posted By: Joey D’Adamo
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jpope wrote:
bbadger wrote:
No reason to bring a neutral to this unit if it is 240 volt.


I've seen these both ways. Can you explain why not?


In a standard one-phase residental power supply, you get

120v between any hot and neutral
240v between both hots

So unless the device requires 120 volts for timers, lights, etc (in this case not), only the two hots are required to get 240v.

I know this doesn't completely help (three phase is all i got in my apartment), but in a three phase power supply, two hots gives you 208v:



Same thing on single phase power, except it would be 240v. No neutral needed.
10

Originally Posted By: jpope
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Thanks Joey and Bob icon_biggrin.gif

–
Jeff Pope


JPI Home Inspection Service


“At JPI, we’ll help you look better”


(661) 212-0738

11

Originally Posted By: jmyers
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Lets take this a step further.


I have had many debates over the neutral/grounding wire.

Take that same appliance, 240 volt, with the green grounding wire. You have two panels, the Service Disconnect and an Equipment Panel. That same appliance is wired into the Equipment Panel. Which bar do you attach the green grounding wire onto? Which bar does the NEC require you to attach the green grounding wire onto? What about other appliances, like a clothes dryer (240 volt)? Water Heater (240 volt)? Heat Pump (240 volt)? Stove (240 volt)? Electric Baseboard Heater (240 volt)? Of course, assuming all three wire!

I like to take the simple approach, when the appliance contains 120 volt circuits, it becomes a neutral making the green or bare grounding wire incorrect. I am glad the NEC is now requiring 4 wires for the 240 volt hookups, clears up a lot of confusion because of the older style 3 wire configurations.

Not that I have installed all that many appliances, but it seems to me like the manufacturers were recommending the third wire was a grounding wire, when really it was a neutral, also making the green or bare grounding wire illegal according to the NEC, correct?

How does the installer know when that appliance contains 120 volt circuits?

If you disconnect that green grounding wire on that 240 volt appliance, will it still run?

--
Joe Myers
A & N Inspections, Inc.
http://anii.biz

12

Originally Posted By: Greg Fretwell
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The only exception to the 4 wire rule for appliances that have a 120v load are ranges and dryers (pre 1996). If you look at the label it will tell you if there is a 120v load. BTW a lot of 240v cooktops (most of them?) will not have any 120v loads.


I still have never understood why dryers used 120v motors. They are usually a special purpose motor and it would have been just as easy to make them 240v. Same with those little bulbs. 240v stuff certainly exists. What do the Europeans use?


It seems a little change in the listing rules around 1946 would have brought this whole mess in line. With volumes in the millions per year price couldn’t have been an issue.

13

Originally Posted By: jpope
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So if this condenser unit was listed as a 120/240 volt system, only then would it have required a four wire connection?

–
Jeff Pope


JPI Home Inspection Service


“At JPI, we’ll help you look better”


(661) 212-0738

14

Originally Posted By: Greg Fretwell
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It would seem so but the real answer is in the installation instructions.


According to the U/L marking guide it should say “120/240 3W” indicating that you need 3 current carrying conductors.

15

Originally Posted By: jmyers
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Jeff P,


You have hit on what is probably the least understood portions of the code requirements.

In the case you are speaking of, you would follow the manufacturers recommendation, wiring as they stated in the installation manual.

You should be careful not to confuse dual voltage ratings on appliances, as wiring requirements. They are not the same. What a dual voltage rating means, is that the appliance can be installed using either voltage.

While I do not doubt Greg F's wisdom, in all my years I have always failed to find any rating on the nameplate, which pertained to 120 volt components installed.

Maybe we could get Greg to take a picture of one and post it here.

I am not sure what is going on with the manufacturers but every appliance that I have ever installed has failed to give instructions on how to properly wire the appliance. Some are nice enough to give you a schematic, but I sure would not bet my life on it. Most of them simply tell you to have a qualified electrician hook it up for you, if you are unsure of how to properly wire it.

To answer your question about the 120/240 volt thing, that would be no. I understand your question but you are not thinking JEFF, 120 volt no matter how you wire it, will always be a three wire. Sometimes you will have 240 volt which require the 4 wire, sometimes 3, depends on what you are wiring.

Water heater, 3
Stove, 4
Cooktop, 3
Oven (I mean the wall ovens, not stoves), 3
Heat pump, 4
Well pump, 3

Now that you are more confused than when you started, HE HE, I just had to laugh! ![icon_cool.gif](upload://oPnLkqdJc33Dyf2uA3TQwRkfhwd.gif)

--
Joe Myers
A & N Inspections, Inc.
http://anii.biz

16

Originally Posted By: Joey D’Adamo
This post was automatically imported from our archived forum.


All the AC condensers I’ve seen were wired with 10/2 or 8/2 (WG of course)… no Neutral to speak of.

17

Originally Posted By: Greg Fretwell
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Joe I have never seen a A/C condenser with a 120v load but if it did the U/L marking guide says it should say “120/240 3W” That means 3 current carrying conductors plus ground. If it just said “120/240” it would indicate dual voltage capability, one OR the other. That would still be 2/wg.

18

Originally Posted By: jpope
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jmyers wrote:
To answer your question about the 120/240 volt thing, that would be no. I understand your question but you are not thinking JEFF, 120 volt no matter how you wire it, will always be a three wire. Sometimes you will have 240 volt which require the 4 wire, sometimes 3, depends on what you are wiring.


I understand that three wires are needed for 120 (H-N-G). I was confused however, about the 120/240 volt listing. I assumed it meant "and" not "or." So I'll rephrase my question.

The only time 4 wires are required is when the equipment has 240 volt components and 120 volt components. Right?

This would explain why the NEC does not distinguish between down stream panels (sub panels) and equipment.

--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738
19

Originally Posted By: Greg Fretwell
This post was automatically imported from our archived forum.


Jeff, in computer rooms it is common that they don’t even bring a neutral to any of the panels. Back in the day everything was line to line loads or it ran from a 208/120v transformer.


I suppose these days they run everything from a single NEMA 5-15 icon_wink.gif

20

Originally Posted By: jmyers
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Jeff P,


120 volt never has four wires, always three. 240 volt on the other hand can have three or four depending on what you are installing. So yes newer codes require the use of four wires when they contain both 120 and 240 volt components.

There has always been much debate over the 3 wire system. Some like to call it grounding, others call it a neutral. Who is correct? I have heard some pretty impressive agruements for both sides. I say it is both, grounding and neutral.

BTW...if you disconnect the green wire on that three wire 240 volt appliance, it won't work. Unless, of course, it is being grounded by some other means, like the earth, a metal pipe, etc.....

I want to know if there is anyone here that is willing to take my up on that question earlier about the 240 volt three wire being attached to which bar on the equipment panel?

Any takers?

--
Joe Myers
A & N Inspections, Inc.
http://anii.biz