heat pump neutral

Reply

  #1  
Old 02-22-04, 07:31 PM
rayjjohnsonjr
Visiting Guest
Posts: n/a
heat pump neutral

Perhaps someone could explain why all my 220v appliances require 2 load wires and a neutral and a ground but the heat pump compressor only has 2 load wires and a ground (that goes nowhere) and NO neutral, and works fine?

Thanks in advance.
 
Sponsored Links
  #2  
Old 02-22-04, 07:35 PM
rayjjohnsonjr
Visiting Guest
Posts: n/a
clarification

Oops, sorry. I got my terms confused. I meant to say they have 2 line wires not load wires (and, I guess, 2 load wires by default).
 
  #3  
Old 02-22-04, 07:58 PM
Speedy Petey's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2003
Posts: 2,455
Received 0 Votes on 0 Posts
If by all you mean your dryer & stove/range it is because they have 120 volt loads built into the unit. Such as a light bulb or timer. They are rated "120/240 volt"

Units such as; an a/c compressor, heat pump compressor, air compressor, big wall a/c, welder, water heater, all do not require a neutral since there are no 120 volt loads in the units. They are straight 220 (or240) volt.
 
  #4  
Old 02-22-04, 08:01 PM
imjerry
Visiting Guest
Posts: n/a
Yes I Think I

Can, most appliances need 220 and 110 to operate, therefore the need for a neutral, however the heat pump only needs 220 Volts so nho need for Neutral!!

Example Dryer , Heating coils run at 220 Volts while the motor usually is 110 Volts

Hopes this help clear it up!!!
 
  #5  
Old 02-22-04, 08:11 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
The only difference between a 120-volt circuit and a 240-volt circuit is the voltage. A circuit only needs two current-carrying conductors no matter what the voltage. The electrons flow in on one and out on the other. When you see three current-carrying conductors going to an appliance, it's because it's really two circuits, one providing 120 volts and one providing 240 volts. Jerry's and Pete's clothes dryer reference is a perfect example.
 
  #6  
Old 02-23-04, 05:52 PM
rayjjohnsonjr
Visiting Guest
Posts: n/a
heat pump neutral

Ok,
Let me see if I can paraphrase:

In a 120 appliance, the line side contributes 120 volts which alternate back & forth through the hot line and dead neutral.

In my 240 v heat pump, the 120v phase A line alternates back & forth across the 120v phase B line while the phase B side is doing the same thing which, in effect, is adding the 2 voltages together making 240 v total. If this is correct, I can deduce that if the 2 cables going to the heat pump each originated from the same line coming off the pole (both phase A for example), then I would have only 120 v power at the compressor which would have to complete the circuit through ground (with less than desired results, I'm sure). True?

So now my curiosity is up, can you recommend a link that might explain the mechanics, if you will, of 3 phase power?
 
  #7  
Old 02-23-04, 06:08 PM
Speedy Petey's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2003
Posts: 2,455
Received 0 Votes on 0 Posts
It's more or less the same thing as single phase, only three ungrounded conductors instead of two.
I'll try and find some links.
 
  #8  
Old 02-23-04, 06:17 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
"dead neutral"??? There's nothing dead about a neutral!

If each hot wire originated on the same line coming off the pole, then there would be no voltage at all between these two wires and you would have no source of 240 volts at the heat pump. If the heat pump had any 120-volt components (and I have no idea whether yours does or not), those would still work. But the 240-volt parts of your heat pump would be dead.

Current should never, ever flow on a grounding wire except in the case of a fault. None of the parts of an appliance that are supposed to conduct electricity are connected to the grounding wire. Unless something breaks, circuits are never completed through the grounding wire. Any time the grounding wire conducts electricity, the breaker should trip if the fault protection is working correctly. When there is a short at the appliance, the grounding wire conducts thousands of amps for thousanths of a second.

By the way, since we are speaking precisely, the term "ground wire" doesn't apply here. You don't have one at the heat pump. You have a "grounding wire" and maybe a "grounded wire" (aka neutral).

Before we move on to three-phase (which is many times more complicated), let's make sure you're clear on single-phase.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: