"Super Neutral"
- Thread starter wannabe
- Start date
- Status
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: "Super Neutral"
That term is found on an oversized neutral conductor. It may be for a feeder to a panel serving non-linear loads, or even on a branch circuit serving a whip to modular furniture.
That term is found on an oversized neutral conductor. It may be for a feeder to a panel serving non-linear loads, or even on a branch circuit serving a whip to modular furniture.
bphgravity
Senior Member
- Location
- Florida
Re: "Super Neutral"
A "super neutral" is simply an oversized neutral. In some cases, up to twice the circular mils of the ungrounded conductors. This is generally only necessary on 3? multiwire circuits and services with additive harmonic currents.
Applications include heavy non-linear loads, such as VFD's, electronics, etc.. A typical dwelling may not benefit from an oversized neutral.
A "super neutral" is simply an oversized neutral. In some cases, up to twice the circular mils of the ungrounded conductors. This is generally only necessary on 3? multiwire circuits and services with additive harmonic currents.
Applications include heavy non-linear loads, such as VFD's, electronics, etc.. A typical dwelling may not benefit from an oversized neutral.
charlie
Senior Member
- Location
- Indianapolis
Re: "Super Neutral"
I really can't get the cape idea out of my mind. I wonder if a copper colored cape would be appropriate?
Sam, don't you have anything better to do than to get foolishness into my head?
I really can't get the cape idea out of my mind. I wonder if a copper colored cape would be appropriate?
Sam, don't you have anything better to do than to get foolishness into my head?
physis
Senior Member
Re: "Super Neutral"
Ever vigilant, our hero, Super Neutral, is on the scene wherever unbalanced current strikes. Never taking any position on anything, Super Neutral, helps even in multiwire branch circuits.
Edit: You have to use a super hero narrator voice.
[ August 19, 2005, 04:16 AM: Message edited by: physis ]
Edit: You have to use a super hero narrator voice.
[ August 19, 2005, 04:16 AM: Message edited by: physis ]
sandsnow
Senior Member
- Location
- Southern California
Re: "Super Neutral"
STOP watching adult swim TV, and get back to studying your code book.Originally posted by physis:
Edit: You have to use a super hero narrator voice.
- Location
- Massachusetts
Re: "Super Neutral"
For panel feeders the most common super neutral I see is simply running double neutrals.
For example a feeder to a 3 phase 225 amp panel might be engineered with five 4/0 CU THHN, one for each ungrounded and two for the neutral.
Please note that this super neutral is basically useless unless the panel is ordered with a larger neutral bus.
Typically what I will see is a 225 amp panel with a 400 amp rated neutral bus. Also this panel should be fed by a transformer that is either over sized or "K" rated.
Now as Ron mentioned super neutrals can also be used on branch circuits, for a 20 amp multiwire branch circuit it is very common to use 12 AWG for the ungrounded and 10 AWG for the neutral.
All of this is design choice and not NEC requirements.
I just recently ran two 3 phase feeders to a small computer room.
Here is what the engineer chose for the job.
80 amp feeder overcurrent protection.
Three 1 AWG CU THHN ungrounded conductors. (Rated 150 amps)
One 2/0 CU THHN Neutral conductor. (Rated 195 amps)
100 amp Main lug panel with standard 100 amp neutral buss.
In my opinion we should have been directed to install a 200 amp Neutral buss if the 2/0 Neutral is expected to be loaded.
IMO Super Neutrals are of questionable value.
I say this because it is unusual to find the circuits in question loaded anywhere near their rating.
A 20 amp circuit feeding non-linear loads is often only loaded up to about 4 or 5 amps.
[ August 19, 2005, 04:51 AM: Message edited by: iwire ]
Not that I have seen, many jobs we do are engineered with super neutrals.
For panel feeders the most common super neutral I see is simply running double neutrals.
For example a feeder to a 3 phase 225 amp panel might be engineered with five 4/0 CU THHN, one for each ungrounded and two for the neutral.
Please note that this super neutral is basically useless unless the panel is ordered with a larger neutral bus.
Typically what I will see is a 225 amp panel with a 400 amp rated neutral bus. Also this panel should be fed by a transformer that is either over sized or "K" rated.
Now as Ron mentioned super neutrals can also be used on branch circuits, for a 20 amp multiwire branch circuit it is very common to use 12 AWG for the ungrounded and 10 AWG for the neutral.
All of this is design choice and not NEC requirements.
I just recently ran two 3 phase feeders to a small computer room.
Here is what the engineer chose for the job.
80 amp feeder overcurrent protection.
Three 1 AWG CU THHN ungrounded conductors. (Rated 150 amps)
One 2/0 CU THHN Neutral conductor. (Rated 195 amps)
100 amp Main lug panel with standard 100 amp neutral buss.
In my opinion we should have been directed to install a 200 amp Neutral buss if the 2/0 Neutral is expected to be loaded.
IMO Super Neutrals are of questionable value.
I say this because it is unusual to find the circuits in question loaded anywhere near their rating.
A 20 amp circuit feeding non-linear loads is often only loaded up to about 4 or 5 amps.
[ August 19, 2005, 04:51 AM: Message edited by: iwire ]
Re: "Super Neutral"
as i know from IEEE paper,if the load is almost nonlinier load,the worst case for the neutral current is 1.73 phase current (3 phase , 4 wire)
so when we oversized neutral it can prevent from fire danger and losses.
but if the harmonic is not too much,it doesn't need to oversized.
the question is when we used supersize neutral ??
i am trying to develop software that can make simulation when we choose a size of neutral then we can compare with any other size from economic and safety aspect.
is there any one can help me ?
thanks
as i know from IEEE paper,if the load is almost nonlinier load,the worst case for the neutral current is 1.73 phase current (3 phase , 4 wire)
so when we oversized neutral it can prevent from fire danger and losses.
but if the harmonic is not too much,it doesn't need to oversized.
the question is when we used supersize neutral ??
i am trying to develop software that can make simulation when we choose a size of neutral then we can compare with any other size from economic and safety aspect.
is there any one can help me ?
thanks
- Status