Not yet as don't have any electrical testing equipment. Thus not using washer/dryer for now until have electrician check it out. If however, there's affordable tester you'd recommend I might give it a try.
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3 wire vs. 4 wire 220v
- Thread starter Mike in Ohio
- Start date
Not yet as don't have any electrical testing equipment. Thus not using washer/dryer for now until have electrician check it out. If however, there's affordable tester you'd recommend I might give it a try.
jav
Well-known member
Not to bring this back up a again but clearly there's some very smart electrical folks here and I have a question... related to generators that output 240 and 120.
I was looking at a freinds (new generator) that had a circular L14-30 (240v) outlet as well as 2 duplex 120V outlets on the gennie. The generator came with a heavy duty extension cord that utilized the 4 prong L14-30 240v output and the other end of the extension cord had 4 - 120V recepticles.
I was trying to figure out which of the 120V recepticals were coming from each individual leg so I could evenly load the 240V out. While doing a continuity check, I found that there were in fact 2 sets (of 2) hot conductors but all 4 neutrals and all 4 grounds were common inside the cord - there was no isolation between the neutrals and grounds.
I find this confusing? I get the current carrying aspect that within a branch circuit- a neutral and ground conductor running in parralel will be at different potentials up to the main neutral and ground buss but my question is- in a typical 120V circuit- doesn't all all neutral current go to ground anyway by virtue of panel bonding?
I guess I don't understand the return curernt theory with respect to X-former center tap neutral, pole grounding, house grounding arrangement. Could someone explain that?
I was looking at a freinds (new generator) that had a circular L14-30 (240v) outlet as well as 2 duplex 120V outlets on the gennie. The generator came with a heavy duty extension cord that utilized the 4 prong L14-30 240v output and the other end of the extension cord had 4 - 120V recepticles.
I was trying to figure out which of the 120V recepticals were coming from each individual leg so I could evenly load the 240V out. While doing a continuity check, I found that there were in fact 2 sets (of 2) hot conductors but all 4 neutrals and all 4 grounds were common inside the cord - there was no isolation between the neutrals and grounds.
I find this confusing? I get the current carrying aspect that within a branch circuit- a neutral and ground conductor running in parralel will be at different potentials up to the main neutral and ground buss but my question is- in a typical 120V circuit- doesn't all all neutral current go to ground anyway by virtue of panel bonding?
I guess I don't understand the return curernt theory with respect to X-former center tap neutral, pole grounding, house grounding arrangement. Could someone explain that?
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pattenp
Well-known member
Portable gens come setup with the neutral and ground bonded internally in the the gen. When a portable gen is used to power circuits in the house the neutral/ground bonding in the gen should be removed. The neutral and ground in a 4 wire gen set cord should not be bonded.
ishiboo
Well-known member
Not to bring this back up a again but clearly there's some very smart electrical folks here and I have a question... related to generators that output 240 and 120.
I was looking at a freinds (new generator) that had a circular L14-30 plug as well as 2 duplex 120V outlets on the gennie. The generator came with a heavy duty extension cord that utilized the 4 prong L14-30 240v output and the other end of the extension cord had 4 - 120V recepticles.
I was trying to figure out which of the 120V recepticals were coming from each individual leg so I could evenly load the 240V out. While doing a continuity check, I found that there were in fact 2 sets (of 2) hot conductors but all 4 neutrals and all 4 grounds were shorted inside the cord.
Doesn't this negate code? I get the current carrying aspect that within a branch circuit- a neutral and ground conductor running in parralel will be at different potentials up to the main neutral and ground buss but my question is- in a typical 120V circuit- doesn't all all neutral current go to ground anyway by virtue of panel bonding?
I guess I don't understand the Center tap neutral, pole grounding, house grounding arrangement. Could someone explain that?
Is
No, first the NEC does not apply.
Also, there's nothing wrong with it. 240v is two 120v legs offset, so when one is at +120v the other is at -120v. (They actually go much higher to +/- 170v, but due to the waveform the RMS value is 120) Neutral is at 0, as is ground.
The NEC requires a single point of connection between ground and neutral - a portable generator is used in place of a supply, so it makes this same neutral/ground connection as the main panel (or meter can) would.
Did you test the cord connected to the generator? If so, it would read that the ground and neutral were connected in the generator. If they are bonded in the cord, it is interesting, but not a big deal. It may be a precaution in case a generator does not have the two bonded (like one intended or once used in a permanent/fixed installation.)
The neutral can be shared as it's just like a MWBC - the neutral only carries the current imbalance (difference) between the two legs. The ground is sufficiently sized for the two 15 or 20A circuits.
jav
Well-known member
No- the cord was bench tested. The neutral/ground connection is in the cord. I didn't test to see if neutral.ground were also bonded at the generator.
I started looking at this because we have on older gennie which uses the 3 wire setup (not the newer 4 wire). For years- when we lost power- I'd switch off the main breaker in the house and leave only essential breaker on PLUS my 240 (3 wire) welder plug in the garage. I then back fed the panel thru the welder plug and we had emergency power for whatever we needed. Redneck yes- but I never had any issues.
With this 4 wire spec- I ws curious then surprised that they were bonded anyway.
I started looking at this because we have on older gennie which uses the 3 wire setup (not the newer 4 wire). For years- when we lost power- I'd switch off the main breaker in the house and leave only essential breaker on PLUS my 240 (3 wire) welder plug in the garage. I then back fed the panel thru the welder plug and we had emergency power for whatever we needed. Redneck yes- but I never had any issues.
With this 4 wire spec- I ws curious then surprised that they were bonded anyway.
pattenp
Well-known member
Because of the cord having the 120V outlets I think ishiboo is correct on the reason the cord is bonded inside is so to make sure when the gen is used as a portable the ground and neutral are bonded. I know on the straight 4 wire cords for connecting the gen to a power inlet, the cord is not bonded internally.
maximumdiy
New member
- Joined
- Jan 13, 2013
- Messages
- 4
Not to bring this back up a again but clearly there's some very smart electrical folks here and I have a question... related to generators that output 240 and 120.
I was looking at a freinds (new generator) that had a circular L14-30 (240v) outlet as well as 2 duplex 120V outlets on the gennie. The generator came with a heavy duty extension cord that utilized the 4 prong L14-30 240v output and the other end of the extension cord had 4 - 120V recepticles.
I was trying to figure out which of the 120V recepticals were coming from each individual leg so I could evenly load the 240V out. While doing a continuity check, I found that there were in fact 2 sets (of 2) hot conductors but all 4 neutrals and all 4 grounds were common inside the cord - there was no isolation between the neutrals and grounds.
I find this confusing? I get the current carrying aspect that within a branch circuit- a neutral and ground conductor running in parralel will be at different potentials up to the main neutral and ground buss but my question is- in a typical 120V circuit- doesn't all all neutral current go to ground anyway by virtue of panel bonding?
I guess I don't understand the return curernt theory with respect to X-former center tap neutral, pole grounding, house grounding arrangement. Could someone explain that?
Return current is confusing mostly in that it's not accurate since current, in a well functioning VAC circuit flows alternatively in both direction in direct relation to the voltage cycle. Think of it as a straw and pushing/pulling liquid through. The straw has to be able to push and pull (voltage) liquid (current) into something. It doesn't really matter what it pulls or pushes into as long as it's able to; it can be a neutral conductor or a ground conductor or another hot.
In a hot/hot/ground configuration (such as with a NEMA 6-50R circuit) both hots pull/push in alternance and there's no draw on the ground connector (except in fault scenarios), in a hot/0 (neutral/ground) configuration, only the hot pulls/pushes into whatever draw it's connected into (ideally the neutral connector so that you can benefit from fault protection via the ground connector (if appliances make use of it) but it doesn't otherwise really matter functionally).
To further clarify both the ground connector and the neutral connector go to the earth at the main panel (neutral also branches out to the transformer center tap on a single phase input feed). Between your outlet and your main panel though, neutral and ground connector need to be distinct if you want to benefit from fault protection via the ground connector. If the ground connector and the neutral are functionally one and the same (bound at the outlet or no insulation between the neutral connector and the ground connector), it still works just fine and you can even benefit from a lesser form of fault protection provided that you have a direct run right back to your main panel.
Regards,
Maximumdiy
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wyliesdiesels
Well-known member
Yes, before i get flamed, i know this is an old thread....
Since most electric dryers have a 120v motor, this wouldnt even be possible.
For CNG, I think one possibility that could be, assuming the washer is properly grounded, is hot and neutral on the dryer terminal block or outlet could be reversed. This would mean that the dryer chassis is hot and when he touches the washer and dryer he is completing a circuit. Also, the heating element(s) would only be getting 120v, thus lending to why the clothes arent drying as fast. But Im not sure if the heating elements would even work on 120v....
Dont know if youve fixed this issue or not but theres a few different affordable testers u could buy. One is a plug in tester, that has 3 lights and will tell u if the outlet is wired correctly. This will work for the washer outlet:
http://www.amazon.com/dp/B002Q3R7HI/?tag=atomicindus08-20
Theres also a GFCI version.
The second tester you could buy is a solenoid type tester, such as a wiggy(I have one made by Sq D):
http://www.amazon.com/dp/B000KII9SM/?tag=atomicindus08-20
or a Fluke digital version:
http://www.amazon.com/dp/B000VRHD4S/?tag=atomicindus08-20
Or this Fluke tester, which has an amp probe as well:
http://www.amazon.com/dp/B0006Z3GZU/?tag=atomicindus08-20
With any of the above, you can verify the voltage between any 2 terminals on the dryer receptacle, to verify that its wired correctly without removing the outlet from the junction box.
I see this wasn't entirely answered:
Electricity doesn't return to earth or ground, it returns to its source. So the return current on a neutral is returning to the center tap on the transformer. Sometimes, if the neutral in a service drop has a bad connection(ie. high resistance connection) and the water company comes out and replaces the water meter, they can get shocked because some return current is flowing through the metal water lines(because of the water line being bonded to the neutral bus in the main service) to the ground rod at the base of the pole and on up to the transformer. There is a ground wire that runs up the pole from the ground rod to the center tap on the transformer.
Actually if polarity was reversed, the dryer would run backwards and the clothes would be wetter at the end of the cycle.
Since most electric dryers have a 120v motor, this wouldnt even be possible.
For CNG, I think one possibility that could be, assuming the washer is properly grounded, is hot and neutral on the dryer terminal block or outlet could be reversed. This would mean that the dryer chassis is hot and when he touches the washer and dryer he is completing a circuit. Also, the heating element(s) would only be getting 120v, thus lending to why the clothes arent drying as fast. But Im not sure if the heating elements would even work on 120v....
Not yet as don't have any electrical testing equipment. Thus not using washer/dryer for now until have electrician check it out. If however, there's affordable tester you'd recommend I might give it a try.
Dont know if youve fixed this issue or not but theres a few different affordable testers u could buy. One is a plug in tester, that has 3 lights and will tell u if the outlet is wired correctly. This will work for the washer outlet:
http://www.amazon.com/dp/B002Q3R7HI/?tag=atomicindus08-20
Theres also a GFCI version.
The second tester you could buy is a solenoid type tester, such as a wiggy(I have one made by Sq D):
http://www.amazon.com/dp/B000KII9SM/?tag=atomicindus08-20
or a Fluke digital version:
http://www.amazon.com/dp/B000VRHD4S/?tag=atomicindus08-20
Or this Fluke tester, which has an amp probe as well:
http://www.amazon.com/dp/B0006Z3GZU/?tag=atomicindus08-20
With any of the above, you can verify the voltage between any 2 terminals on the dryer receptacle, to verify that its wired correctly without removing the outlet from the junction box.
Not to bring this back up a again but clearly there's some very smart electrical folks here and I have a question... related to generators that output 240 and 120.
I was looking at a friends (new generator) that had a circular L14-30 (240v) outlet as well as 2 duplex 120V outlets on the gennie. The generator came with a heavy duty extension cord that utilized the 4 prong L14-30 240v output and the other end of the extension cord had 4 - 120V receptacles.
I was trying to figure out which of the 120V receptacles were coming from each individual leg so I could evenly load the 240V out. While doing a continuity check, I found that there were in fact 2 sets (of 2) hot conductors but all 4 neutrals and all 4 grounds were common inside the cord - there was no isolation between the neutrals and grounds.
I find this confusing? I get the current carrying aspect that within a branch circuit- a neutral and ground conductor running in parallel will be at different potentials up to the main neutral and ground buss but my question is- in a typical 120V circuit- doesn't all all neutral current go to ground anyway by virtue of panel bonding?
I guess I don't understand the return current theory with respect to X-former center tap neutral, pole grounding, house grounding arrangement. Could someone explain that?
I see this wasn't entirely answered:
Electricity doesn't return to earth or ground, it returns to its source. So the return current on a neutral is returning to the center tap on the transformer. Sometimes, if the neutral in a service drop has a bad connection(ie. high resistance connection) and the water company comes out and replaces the water meter, they can get shocked because some return current is flowing through the metal water lines(because of the water line being bonded to the neutral bus in the main service) to the ground rod at the base of the pole and on up to the transformer. There is a ground wire that runs up the pole from the ground rod to the center tap on the transformer.
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theoldwizard1
Well-known member
Everyone knows I am an "old school" guy ! But I just learned about an old school tool that I had NEVER heard of !!...
The second tester you could buy is a solenoid type tester, such as a wiggy
Basically is is a very heavy duty, low impedance volt meter. HD meaning throw it in you tools box, drop it off of an 8' ladder and it should survive. "Low impedance" means it won't be bothered by "ghost voltages" (another topic completely). Many modern digital multimeters pick up ghost voltage, unless they have a low impedance (low Z) selection.
They are really more of a "go/no go" tester (yes, you have 120/240/480V or no you don't).
For the average homeowner, I think a con-contact voltage detector is more useful, even if they do sometimes give false positives.
wyliesdiesels
Well-known member
Everyone knows I am an "old school" guy ! But I just learned about an old school tool that I had NEVER heard of !!
Basically is is a very heavy duty, low impedance volt meter. HD meaning throw it in you tools box, drop it off of an 8' ladder and it should survive. "Low impedance" means it won't be bothered by "ghost voltages" (another topic completely). Many modern digital multimeters pick up ghost voltage, unless they have a low impedance (low Z) selection.
They are really more of a "go/no go" tester (yes, you have 120/240/480V or no you don't).
For the average homeowner, I think a non-contact voltage detector is more useful, even if they do sometimes give false positives.
The wiggy, which I still have, was one of the very first tools i bought and used as an apprentice!! Yes, they are rugged.
Yes, an inductive, non contact voltage tester should also be a must have tool. Though, for CNG's issue, it wouldnt be very useful or tell him anything more than he already knows!