Electrical "Legality" Questions

Can a cable rated at 100A support a full continous 12K load?

Yes (unless your voltage is below 120 Volts):
At 120 Volts a "12K" (12,000 Watt) load draws 100 Amps. 
At 240 Volts a "12K" (12,000 Watt) load draws 50 Amps.

What is the maximum length of cable for 1000 watt loads in 16 gauge, 14 gauge, 12 gauge and 10 gauge?

Wire Gauge
Voltage Drop
Maximum Length

What's the difference between ETL Listing & UL Listing?

None. UL is more widely known, which may have some marketing benefits, but ETL is also certified as a "Nationally Recognized Testing Laboratory" and products that are ETL approved have been tested to the same standards as UL.

Is a "Sister-lug" "legal"?

The Sister-Lug is a type of bussbar clamp used for feeder connections in the West Coast Studio Industry. Approved and "legal" versions are available from TMB and Mole-Richardson.

Is a "Studio Pin" "legal"?

No. The NEC requires connectors used on feeders to be "Listed and of the locking type" - the traditional "Studio-Pin" is neither.

Should I buy Type W feeder cable or Entertainment Grade? Are they both equally "Legal"?

Listed "Type W" and "Type SC" (Entertainment Grade) feeder cables are both specifically mentioned in the NEC as "legal" for entertainment applications. TMB supplies both types: The "Type W" feeder cables are more durable, but also heavier and more expensive. The "Type SC" feeder cables are less durable but also less expensive and lighter in weight. The "Type W" is also approved for a wider range of applications than the "type SC". TMB would recommend "Type W" for general use and "Type SC" for certain applications such as on studio lots.

Are single-pole cam type connectors legal or do I have to use an interlocked system?

Regular single-pole cam type connectors are only legal when used by "qualified persons". If your feeder connections are not being made and unmade by qualified, trained professionals, you must use some kind of Interlocked system.

Is all "Type W" cable legal?

No. Type W is available in versions that are not UL Listed, these versions are not allowable for Entertainment Industry applications.



This email address is being protected from spambots. You need JavaScript enabled to view it.

The TMB Binder in one PDF file
Keep yours up-to-date
US Letter | Europe A4

Follow TMB on Facebook

Follow TMB on Twitter