stranded wire

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SceneryDriver

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Electrical and Automation Designer
I had the pleasure of running 300MCM wire on Friday. Why do we do this to ourselves? Strand counts need to go up on larger wire sizes - it was like wrestling frozen garden hose. I'd be willing to pay a few % more if it meant I wasn't too exhausted to move my hands after after a day of landing that stuff in a meter pan and disconnects. I know wire types like DLO exist, but I don't think it needs to be that finely stranded. Just a little more finely stranded than a bundle of 12awg solid wires :)



SceneryDriver
 
The finer and more-numerous the strands, the more challenging it is to make reliable, long-lasting connections.

DLO absolutely requires special crimp connectors and tooling. Beyond about 37 strands, a setscrew or two just doesn't cut it -- the increased flexibility also means increased creep and loosening over time.
 
The largest that I ever worked with was 750 cu. It was a 2500 amp service with (6) parallel sets. It took a little bit of elbow grease to terminate the MDP. Fortunately the enclosure had plenty of room but it was still hard work.
 
drcampbell said:
The finer and more-numerous the strands, the more challenging it is to make reliable, long-lasting connections.

DLO absolutely requires special crimp connectors and tooling. Beyond about 37 strands, a setscrew or two just doesn't cut it -- the increased flexibility also means increased creep and loosening over time.
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Ferrules largely solve the fine strand issue. We use them all the time in Entertainment wiring, where 4/O (welding cable) conductors with 2000+ strands need to be terminated in lugs and Cam-Lock connectors. I'm certainly not saying we need 2000+strand wire, but something with a bit more flexibility would certainly be helpful.


SceneryDriver
 
Rick 0920 said:
The largest that I ever worked with was 750 cu. It was a 2500 amp service with (6) parallel sets. It took a little bit of elbow grease to terminate the MDP. Fortunately the enclosure had plenty of room but it was still hard work.
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OOOF!! That must've been a fun day. I'd call the local zoo and ask to borrow their gorilla if I had to do wire that big :)


SceneryDriver
 
Largest I've ever delt with was 500MCM. The hands were sore for a few days after every install. I hated that crap.
 
LarryFine said:
A conduit bending hickey can help, or even a bender..
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I used to use the hole in the end of a 12" crescent wrench. It was smooth all the way around and wouldn't leave any marks if done easily. This was way before we say any of them fancy tools hit the market.
 
SceneryDriver said:
.... I'd call the local zoo and ask to borrow their gorilla if I had to do wire that big :)
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While working at a university wind-tunnel facility, we needed to disassemble a large valve. (the body was a 2- or 3-foot steel cube and it was rated for 4000 or 5000 lbf/in2) Even a 12-foot cheater bar with two humans wasn't sufficient, so we settled on pulling a wrench with a chain with a forklift. It was slow going, because we could only move it a foot or two in the confined space, and had to stop frequently to let the exhaust fans catch up with the exhaust. (pre-emission-control carburetted engine)

An Indian graduate student wandered through, saw our work in progress, and in all seriousness, said, "This would be a lot easier if you had an elephant here."

The facility's only a few miles from the Columbus Zoo, then run by the inveterate showman Jack Hanna, and for a brief moment, we actually considered asking to borrow one.
 
LarryFine said:
That's one of the reasons paralleled smaller conductors are often used.
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If I could've used them, I probably would've. PoCo didn't want parallel conductors on a service less than 400A; it was a 320A overhead service. I love their made up rules.


SceneryDriver
 
SceneryDriver said:
If I could've used them, I probably would've. PoCo didn't want parallel conductors on a service less than 400A; it was a 320A overhead service. I love their made up rules.


SceneryDriver
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It's a shame that POCO can make rules that don't apply to them. We can parallel conductors 1/0 and larger. We can also use parallel 500's for an 800 amp service per 240.4
 
drcampbell said:
I can envision that it might be a hassle to connect multiple conductors flailing about in free air while you're working from a bucket truck. Does the same rule apply to pad-mounted transformers?
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Oddly enough, it was me making the tie-in connections (live) from a boom lift. PoCo couldn't be bothered to come out and do a disconnect/reconnect on a schedule.


SceneryDriver
 
SceneryDriver said:
It was copper. Only upside was it let me fit into 2" EMT, and not have to upsize.


SceneryDriver
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Yeah that can certainly be a consideration and sometimes the deciding factor, not having to upsize the pipe.

Sometimes going to two sets is worth it, even after derating. For example you could go with two sets of 3/0 aluminum with a one size reduced neutral...... That is somewhat of an odd size though and may not have the best availability in stock.
 
electrofelon said:
Yeah that can certainly be a consideration and sometimes the deciding factor, not having to upsize the pipe.

Sometimes going to two sets is worth it, even after derating. For example you could go with two sets of 3/0 aluminum with a one size reduced neutral...... That is somewhat of an odd size though and may not have the best availability in stock.
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I actually went with 300MCM phase conductors, and a 3/O neutral, in copper. My house fits on a 150A service; the 320A service is to support EV charging in a few years, which is a 240V load. Inspector was OK with not having a monster neutral for no good reason, once I explained the rationale for the "oversized" service.


SceneryDriver
 
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