208 single
phase derived off of 2 of the 3 legs of a 3
phase system is very common around movers. What is typically the
neutral is the second hot
leg and
ground always remains
ground. Typically these 208 v connectors have a different color shell but work the same as a typical 120v
plug when connected to a 120v
soco. Typically when you on the
road you have 3-4 groups of
soco. 120v dimmed circuits, 120 non dimmed for Foggers, video displays, LEDs, and so forth, and 208 non dimmed for movers. Sometimes you will have audio guys who use
soco to feed their
line arrays. Personally I like using
stage pin for dimmers,
Edison for 120v, and L6-20, L6-30 for 208v stuff than there is no confusion, though in all cases label, label, label. All
soco looks the same though the voltages will not be.
This thread proves to me, without doubt, that electrical training in our industry is not in good shape. There is an astonishing amount of ignorance and bad practice encapsulated here. Furthermore, the fact that these "solutions" are being promulgated on a public forum where many non-professionals hang out just makes the situation even more egregious. I think some critical points have been missed in the discussion:
1.
NEMA connector types exist for an important reason: when one encounters a given type, say a 5-15, ones wants to be
assured that the nominal
voltage present at the
connector is that of the
connector rating (125V) and the branch
circuit will support the
current rating of the
connector (15A).
2. Using connectors at ratings other than their marked ratings breaks the assumption of (1) above. This is dangerous anarchy, with life-safety implications. It makes no difference that the copper in the
connector can deal with the improper
voltage and current--this is an issue of known ratings and non-interchangeability.
3.
Every ungrounded conductor in a
circuit needs an
overcurrent protective device. A single-phase 208V
circuit has
two ungrounded conductors, thus requiring
two poles of
overcurrent protective device. If those two poles are breakers, they need to be handle-tied with a method
identified for the purpose. Using neutrals as ungrounded conductors in a
power distribution breaks this two-pole requirement, as
neutral conductors are not allowed to have overcurrent protective devices. This is extremely dangerous, since a
circuit wired in this manner has one pole 120V above
ground, even with all overcurrent protective devices tripped, blown, or shut off.
4.Socapex-type 19-pin connectors used with two different pinouts (120V and 208V circuits) remain an ongoing
safety problem for our industry, and one that has resisted non-interchangeability solutions that have been put forward. The tremendous volume of
Socapex trunk cables in worldwide rental inventories may have something to do with this. If the inspection community ever gets their teeth into this issue, the decision about a solution will be taken out of the hands of our industry.
Many of us have done astonishingly dangerous and dumb things in our careers, me included. However, as I learned more, I did fewer stupid things. "My boss told me to get it done" can never be a justification for poor planning that requires a dangerous solution. This forum is a nexus of many people who are experts in this field, and experts in
safety. They are not experts in "what can you get away with". I suggest that some of the participants in this thread would do well to increase their
level of knowledge and their commitment to
safety.
ST