KyleFowler
Member
- Location
- Maryville, TN
- Occupation
- Electrician
so for years I've hooked up plenty of cubicle whips and they always had that #10 neutral that was the common for three #12 ungrounded phases. I never knew why they were made this way until today.
Basically I'm working on a remodel job that had tons of cubicles but then when the business shut down all the cubicles were removed. Now a new business is moving in and we have to provide power for the cubicles they bring in. So I look at the existing building wiring and I am shocked to see for the first time in my life #10 neutrals being paired with 20 amp circuits that share a neutral. This job is even more unique as we have the original blueprints for when this job was wired in '95 and that's were I learned of the term "Super Neutral" after seeing it on the blueprint. These #10 neutrals were specified for all cubicle circuits that shared neutrals. I've never seen that before.
So I go online and look up what is the deal with Super Neutrals and I am overwhelmed with technical information way above my knowledge. For years and years we wired lights and plugs "three hots to a neutral" but never upsized the neutral when doing so.
So here are my questions:
1. How do you know when to upsize your neutral? I read this has to do with power supplies from computers, etc. putting extra current on the neutral from the 3rd harmonic or something but I have no idea how serious this issue is? Obviously my understanding on this is fuzzy at best. As a real world example on this job we are supplying power to 6 cubicles off of one cubicle whip with three hots and a neutral. So basically each circuit is feeding two cubicles a piece. Is 6 computers and monitors enough to overload a shared neutral? It doesn't seem like it but again those original blueprints from '95 seems to think so. (the new setup is somewhat similar to the original)
2. Has anyone ever seen a shared #12 neutral burn up because of additive 3rd harmonics? I never have.
3. Am I overthinking this? LOL
Sorry for the long post!
Basically I'm working on a remodel job that had tons of cubicles but then when the business shut down all the cubicles were removed. Now a new business is moving in and we have to provide power for the cubicles they bring in. So I look at the existing building wiring and I am shocked to see for the first time in my life #10 neutrals being paired with 20 amp circuits that share a neutral. This job is even more unique as we have the original blueprints for when this job was wired in '95 and that's were I learned of the term "Super Neutral" after seeing it on the blueprint. These #10 neutrals were specified for all cubicle circuits that shared neutrals. I've never seen that before.
So I go online and look up what is the deal with Super Neutrals and I am overwhelmed with technical information way above my knowledge. For years and years we wired lights and plugs "three hots to a neutral" but never upsized the neutral when doing so.
So here are my questions:
1. How do you know when to upsize your neutral? I read this has to do with power supplies from computers, etc. putting extra current on the neutral from the 3rd harmonic or something but I have no idea how serious this issue is? Obviously my understanding on this is fuzzy at best. As a real world example on this job we are supplying power to 6 cubicles off of one cubicle whip with three hots and a neutral. So basically each circuit is feeding two cubicles a piece. Is 6 computers and monitors enough to overload a shared neutral? It doesn't seem like it but again those original blueprints from '95 seems to think so. (the new setup is somewhat similar to the original)
2. Has anyone ever seen a shared #12 neutral burn up because of additive 3rd harmonics? I never have.
3. Am I overthinking this? LOL
Sorry for the long post!