Cam-Lok Connections

STEVETERRY

Well-Known Member
NEC 520 and 525 permit single-pole separable connectors to connect portable switchboards if one of several conditions are met - keyed mating connectors to prevent line/neutral/ground misconnection, physical interlocks that force connection order, all the way down to posted warnings and instructions to the qualified personnel regarding connection/disconnection order.

The reason we see reversed gender neutral and ground (with respect to line gender) is it's the easiest, cheapest way to prevent connection to a Line and create a direct short at 400 amps...

CEE form connectors, up to 100 amps, meet the "normal" Code requirement of having Ground connect first/disconnect last, and all line connections connect/disconnect together.
As of 2020, single-pole separable connectors have moved to NEC section 406.13, in recognition of the fact that these devices are also used in occupancies other than theatres and studios


ST
 

Apmccandless

Active Member
The only thing I would suggest is to speak with you electrical contractor and AHJ for electrical inspections. I was working on a school install and failed for this reason. The inspector said that receptacles are female and plugs are male. While the NEC may not have an opinion your inspector certainly may. In the end the inspector will be the one who interprets the code and, odds are, your electrician will do it the way the inspector wants it.
 

STEVETERRY

Well-Known Member
The only thing I would suggest is to speak with you electrical contractor and AHJ for electrical inspections. I was working on a school install and failed for this reason. The inspector said that receptacles are female and plugs are male. While the NEC may not have an opinion your inspector certainly may. In the end the inspector will be the one who interprets the code and, odds are, your electrician will do it the way the inspector wants it.
However, it would be worth noting that we are talking about grounded and grounding conductors, not ungrounded phase conductors. In this case, reverse gender creates absolutely no safety hazard.

ST
 

RickR

Well-Known Member
I'm with @Apmccandless this. I was taught long ago

"An inspectors opinion has the force of law. They can be wrong, but over ruling them is usually more trouble than it's worth."
 

ship

Senior Team Emeritus
Premium Member
Reverse Ground/Neutral the best way to go as with having a set, but letting the tour ask for it.

Cost of Male or Female CamLoc is the same. Your supplier will easily do what you want unless buying something pre-made in needing to change which would probably be a write off in price negotiated.
 

STEVETERRY

Well-Known Member
If it is so hard to challenge an obviously wrong decision then something is badly wrong in your system, surely?
There is a reason they are called "the Authority Having Jurisdiction".

Sometimes, their mistaken interpretation will result in a clarifying change to the NEC. A good example is this:

Part II. Fixed Stage Switchboards
520.21 General

(1) Fixed stage switchboards shall be listed.
(2) Fixed stage switchboards shall be readily accessible but shall not be required to be located on or adjacent to the stage. Multiple fixed stage switchboards shall be permitted at different locations.
(3) A fixed stage switchboard shall contain overcurrent protective devices for all branch circuits supplied by that switchboard.
(4) A fixed stage switchboard shall be permitted to supply both stage and non-stage equipment.
(5) Fixed stage switchboards shall comply with the marking and working space requirements in 408.18(C) but shall not be required to comply with the load terminal location requirements in 408.18(C)(1), (C)(2), and (C)(3).

The highlighted orange text was added after an AHJ insisted the NEC required that a dimmer rack must be installed adjacent to the stage.

Often, a conversation with the AHJ and one of our industry Code Panel 15 members can have some positive effect.

You can be sure that in the 2026 NEC cycle, there will be a proposal to create wording to clearly resolve this gender issue on single-pole separable connectors. :)

ST
 

almorton

Well-Known Member
That's all good, but my point was about the inability to challenge an inspector's decision, even if it was clearly incorrect, for whatever reason.
 

RonHebbard

Well-Known Member
Premium Member
Some day I'll post the details of our local AHJ having his interpretation overturned by his provincial superior resulting in our having to remove part of a 400 Amp 3 phase installation and reinstall it to his boss's satisfaction.
Toodleoo!
Ron Hebbard
 

SteveB

Well-Known Member
That's all good, but my point was about the inability to challenge an inspector's decision, even if it was clearly incorrect, for whatever reason.

You can (sometimes) challenge an inspector. We had a NYC electrical inspector who would add items to a punch list every time he visited to inspect corrections to the items on the previous punch list. It got ridiculous and the contractor finally filed a legal complaint with the NYC building Dept. They got a new inspector out who signed off.
 
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Footer

Senior Team
Senior Team
Premium Member
I like them swapped. I also have turn arounds for all 3 of my company switches. Everyone who is touring should carry turn arounds too... and they should carry tails as well for the handful of places that still have to do bare end tie ins.
 
If this was in my home venue, I'd have two neutrals and one ground source on male connectors, keep back to back female gender benders available nearby SECURELY LOCKED UP to prevent from escaping with the next tour passing through. This worked well for us with 3 phase / 5 wire / dual redundant neutral four ought in 1973.
Toodleoo!
Ron Hebbard

Could you explain why some company switched have (2) neutrals?

Is this in case the 3-phase load isn't balanced and has to draw more current on the neutral than the (3) line conductors?
 

RonHebbard

Well-Known Member
Premium Member
Could you explain why some company switched have (2) neutrals?

Is this in case the 3-phase load isn't balanced and has to draw more current on the neutral than the (3) line conductors?
Dual SCR &/or IGBT dimmers achieve a less than flawless power factor, especially when operated at levels less than full and above zero.
If everything was perfectly balanced, in theory the neutral would carry zero current.
The world of theatrical dimming is less than perfect and, in certain situations, the neutral can carry more current than the 3 phases.
Read up on "Triplen Harmonics".
Toodleoo!
Ron Hebbard
 

TimMc

Well-Known Member
Premium Member
Could you explain why some company switched have (2) neutrals?

Is this in case the 3-phase load isn't balanced and has to draw more current on the neutral than the (3) line conductors?

Harmonics aside (and Ron, as usual, is spot on...) you are correct that it's possible to overload a single neutral conductor of the same ampacity as a line conductor.

Fully loading phase A, with no loads of phases B and C would create a sufficient imbalance to require double the current carrying capacity of the neutral conductor.

Since we know what happens in 3 phase wye service, my question: what happens with such a current imbalance in a Delta service? 🕶️
 

STEVETERRY

Well-Known Member
Harmonics aside (and Ron, as usual, is spot on...) you are correct that it's possible to overload a single neutral conductor of the same ampacity as a line conductor.

Fully loading phase A, with no loads of phases B and C would create a sufficient imbalance to require double the current carrying capacity of the neutral conductor.

Since we know what happens in 3 phase wye service, my question: what happens with such a current imbalance in a Delta service? 🕶️
The situation you describe above with only A phase loaded in a wye service would not cause neutral overcurrent. Neutral overcurrent occurs with nonsinusoidal current waveforms on the three phases. Most frequently, this can occur when phase-control dimmers on the three phases are set to levels less than full.

I have attached a file entitled "Some Neutral History". It documents the first time we discovered the neutral overcurrent condition at Production Arts in the early 1980's, and provides observations on the conditions causing the worst neutral overrcurrent on a phase control dimming system.

ST
 

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Jay Ashworth

Well-Known Member
The situation you describe above with only A phase loaded in a wye service would not cause neutral overcurrent. Neutral overcurrent occurs with nonsinusoidal current waveforms on the three phases. Most frequently, this can occur when phase-control dimmers on the three phases are set to levels less than full.
Thanks for replying to that; that didn't sound right to me, but I'm not you. :)
 

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