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In Reply to: RE: Learn more here about compliance labelling posted by budm on February 12, 2009 at 22:43:38
The article does not say if a balanced power system is Listed for use in a residential occupancy. The article only relates to safety testing.
Kind of like an off the wall example of a gas generator having a safety UL listing and then going onto say because it is Listed it could be used inside a home. The listing is given for the intended use......
Is the intended use of a 60/120Vac balanced power system safety Listed for use by the general public in their home?
I sent an email to Jerry Hoopes at Panamax asking him if a 60/120Vac, balanced power, system is listed for use in a residential occupancy.
I will post Mr Hoopes response, if he responds to my email.
Jim
Follow Ups:
you can also send an email to either Panamax or Furman customer support.
> >
I guess they are saying, hey look at us we do the same thing as balanced power but without being balanced. I don't think that is possible.
The NEC is subject to interpretation by you, me, the AHJ, the insurance companies, UL, etc. My interpretation is that a consumer electronic device such as a BPT box is a consumer electronic device and has the markings and the GFI required by NEC, etc. An AHJ (electrical inspector) is never going to see a BPT box during a residential electrical inspection. My "opinion" on the insurance company part of it is that whatever box you have, if it causes a fire, better have a UL, ETL or some 3rd party testing agency label on it or there will be problems.
If a balanced power transformer in a box solved some sort of audio/video problem for me or transformed the sound of my system, then I would install one in a heartbeat. I have played around with a small one and it hasn't done anything for me positive or negative. I have some older LC circuit filter boxes (MIT) and they do work, in my system, to great affect.
Also, not sure how this would be interpreted but there are lots of multichannel amps that use a balanced power transformer in them. Of course they don't have receptacles built into them to plug in appliances or other consumer electronic devices.
"E pur si muove...And yet it moves"
The NEC is subject to interpretation by you, me, the AHJ, the insurance companies, UL, etc. My interpretation is that a consumer electronic device such as a BPT box is a consumer electronic device and has the markings and the GFI required by NEC, etc. An AHJ (electrical inspector) is never going to see a BPT box during a residential electrical inspection. My "opinion" on the insurance company part of it is that whatever box you have, if it causes a fire, better have a UL, ETL or some 3rd party testing agency label on it or there will be problems.
NEC 647 needs no interpretation.......
647.1 Scope. This Article covers the installation and wiring of separately derived systems operating at 120 volts line to line and 60 volts to ground for sensitive electronic equipment.
647.3 General. Use of a separately derived 120-volt single phase 3 wire system with 60 volts on each of two ungrounded conductors to a grounded neutral conductor shall be permitted for the purpose of reducing objectionable noise in sensitive electronic equipment locations, provided the following conditions apply:
(1) The system is installed only in commercial or industrial occupancies.
(2) The system's use is restricted to areas under close supervision by qualified personnel.
(3) All of the requirements in 647.4 through 647.8 are met.
647.7 Receptacles.(1) All 15- and 20-ampere receptacles shall be GFCI protected.
(2) All receptacle outlet strips, adapters, receptacle covers, and faceplates shall be marked with the following words or equivalent:
WARNING- TECHICAL POWER
Do not connect to lighting equipment.
For electronic equipment use only.
60/120 V 1ph ac
GFCI protected
======================================================I have not seen any proof that any Listed testing lab has approved a 60/120V separately derived grounded power system for use in a residential occupancy. I have read where the equipment has been safety tested. But I have not read anything that says Article 647.3 is waived and the unit is approved for home use.
If a balanced power transformer in a box solved some sort of audio/video problem for me or transformed the sound of my system, then I would install one in a heartbeat.And that would be your choice..... And if for any reason you or a family
member were to be injured from your decision that will be on your shoulders.But if a manufacture, or dealer, represents the unit as "safety listed approved" for in home use and it turns out the unit is not...... Then jmho, take a copy of NEC 2008 Article 647 with you to the lawyer's office....
Edits: 02/16/09
sell them all day long to residential based consumers. Evidently their lawyers and insurance companies think their product is safe and that they have legal legs to stand on.
As to the code, it is interpreted and misinterpreted every day by AHJ's and others. I have been an electrical engineer involved in the design and construction of residential, commercial, industrial and medical facilities for 25+ years. Manufacturers sit on the code committees and push thru revisions and additions that suit their agendas. It didn't use to be that way but it is now and has been for some time. Some municipalities stopped adopting new code back in the 70's and their is still a movement to reject the NEC and adopt a best practices or standards in lieu of NEC code compliance.
I won't debate the safety of balanced power transformers. There is an inherent shock hazard if misapplied. I will however debate the necessity and interpretation of the all mighty NEC. There is good, safe, well engineered/designed electrical systems and then there is "code compliance". Cheers!
"E pur si muove...And yet it moves"
Jim,NEC 647.1 (Scope) outlines the requirements for separately derived 120V L-L / 60V to ground systems. The key term here is 'separately derived'. Note that the term "Balanced Power" is not defined nor used within NEC.
Per NEC 100 (Glossary), Separately Derived is defined as:
"A premises wiring system whose power is derived from a source of electric energy or equipment other than a service. Such systems have no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system."All Panamax and Furman products include a solid/direct ground connection back to the panel through the premise wiring and therefore do not fall under the classification of separately derived and the requirements of NEC 647.
All Panamax and Furman products are evaluated for safety by OSHA accredited Nationally Recognized Test Labs (NRTL) including Underwriters Laboratories, Intertek Testing Services (ETL) and TUV. The safety standards applied in the test and evaluation state that products shall additionally comply to the requirements of NFPA 70 (NEC) so compliance to NEC has been considered in the evaluation.
It is my understanding that the requirements in the NEC are for 120V/60V systems installed near the service panel and that distribute power as part of the premise wiring rather than point-of-use products such as ours. Given that we have been granted safety certification on these products by multiple NRTLs reinforces that conclusion.
If you have any additional questions, please do not hesitate to contact me directly.
Best Regards,
Jerry Hoopes
Engineering Manager
Panamax / Furman
(707) 766-2316> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
-----Original Message-----
Sent: Friday, February 13, 2009 7:09 AM
To: Jerry Hoopes
Subject: Balanced AC power system for use in a residential occupancies.Jerry,
Article 647 of the NEC states that a 60/120 volt, balanced power, system
shall only be permitted for use in commercial or industrial occupancies.
647.3 also requires the system use be restricted to areas under close
supervision by qualified personnel.So my understanding of NEC 647.3 is that a 60/120Vac system can not be used
in a residential occupancy.So am I correct that cord and plug balanced power systems are not Listed for
use in residential occupancies?Would appreciate your comments.
Regards,
Jim> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > .
Edits: 02/13/09
you can also send an email to either Panamax or Furman customer support.
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