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I agree, this looks very, very much like the thermal ammeters that we once installed in substations for feeder load monitoring, and (minus the instantaneous meter) that we still sometimes install for transformer monitoring. Oddly, we still have ours catalogued internally as a Sangamo Electric...

I guess this has to do with NEC 110.26(F)(1)(a). Our 2008 NEC Handbook explains, "This reserved space permits busways, conduits, raceways, and cables to enter the equipment," which confirms dpc's explanation.

re: the Wikipedia, I don't think there was such an initiative (or if there was, it was dropped). They do require registration in order to do certain things, like create pages, but that's nowhere near the same thing as requiring credentials. I'll say this much for it, anyway: it's a good source...

That's the one. I hate going to IEEE Xplore to look things up, though, so for those of you that also don't care for Xplore, or just do not have access, the official citation is: Energy savings from PQ mitigation technologies[:] Techniques for evaluating vendor claims Howe, B. EPRI, Palo...

There was a great paper by Bill Howe of EPRI in this year's IEEE T&D conference proceedings about evaluating exactly this sort of claim about this sort of device. I'll have to dig out the details if anyone's interested, but it's a fairly plain-language paper, maybe the kind of thing to show a...

It turns out the 15-foot rule is a part of our rates, nothing more (at least, nothing that I could find). It figures, but at least that's enough to justify keeping it in the practice for now. LPS for magoo, though. I compared the costs of replacing a two-set service lateral against replacing...

magoo, If it's a short, heavy service (3+ cables), then that makes some sense: at upwards of $2000 per set of cable, the limiters don't provide much of a savings over letting a faulted cable burn off. The fault current divides across the other sets and doesn't damage them, if there are enough...

I'm reviewing some of our old distribution system design practices at the moment, and one that I'm looking at has to do with the application of cable limiters on our secondary network. In short, at 208V it calls for cable limiters on all of the main distribution cables, and on services when...

I'll try to answer based on what I've designed on previous jobs: (1) I think has been answered above. (2) A vault is probably not required unless this is oil-filled gear, which it most likely is not. Assuming this is not utility-owned, check Article 490 of NEC for some information. (3) Some...

For what it's worth, we do install some 300 amp meters (class 320, actually) on single-phase 400A services, usually big residential services. For example: http://www.geindustrial.com/cwc/Dispatcher?REQUEST=PRODUCTS&pnlid=5&id=kvcl320

I agree that the interrupters are overkill if the laterals are already fused. Animal guards may work, or more likely you need to reevaluate your cable pole construction standards/practices to reduce the potential for animal contacts. What two points are the animals contacting to fault the...

Aside from the question of flying manhole covers, there are more practical concerns. How tall is the equipment in the vault? Will the repair crew later be able to get it out without demolishing the patio? What kind of rigging will they need in order to accomplish that? Code or not, it's not...

You should use a fire-rated door here, especially if these are liquid-filled transformers. There's no good reason to give a transformer fire a chance to get out of hand, especially with the building hanging over the delivery area like it does. Too much potential for a fire to spread...

Yes, I've designed installations of these anodes on our system. In our case, they're 44 lb. magnesium anodes, protecting lead-covered cables. The anode ties to the cable bonding through a pair of lugs at the manhole neck, apparently so the corrosion engineer can break the circuit to check...