Ground strap required on external cabinet doors?
Ground strap required on external cabinet doors?
(OP)
Was wondering if anyone knows if there is a code REQUIREMENT for ground-bonding straps ACROSS cabinet door hinges bonding the metallic door to the enclosure as oppossed to simply grounding through the hinges.
Any advice would be appreciated,
Thanks
Any advice would be appreciated,
Thanks






RE: Ground strap required on external cabinet doors?
RE: Ground strap required on external cabinet doors?
Most doors on switchgear are bolted by metal hinges which provides adequate groung continuity so further strapping is not necessary.
Engineers often specify and insist the requirement not knowing that its just a folly
RE: Ground strap required on external cabinet doors?
http://www.ormec.com/motion/mktdocs/shldgrnd.htm
For: Use ground straps made from 1 inch (25 mm) silver tinned flat copper braid to connect the cabinet door(s) to the enclosure, the first sub-panel to the enclosure, and from each sub-panel to the next.
RE: Ground strap required on external cabinet doors?
Reliable continuity for fault currents and limited potential difference cannot be consistently achieved solely through door hinges—given routine paint, lubricant and corrosion.
RE: Ground strap required on external cabinet doors?
In europe hinges would be classed as a "fortuitous" earth. To ensure touch potentials are low whilst fault currents flow, a positive mechanism for earthing must be applied using a strap. Hinges are not designed to carry current, so cannot be gauranteed. I wouldn't touch it!!!!
For EMC protection, straps are no good, you must use an EMC gasket to totally seal the door, but that's another story/thread..............
RE: Ground strap required on external cabinet doors?
What you say may be true, but it is not normal practice in the US to provide a bonding strap to panel doors.
The link given by jbartos is concerned with EMI protection of sensitive equipment and 300 MHz harmonics not safety for faults.
RE: Ground strap required on external cabinet doors?
The components (usually metering) rarely exceed 220v and backed up by a fuse not exceeding 10A, so where are these high fault currents coming from!
They never have bonding straps on washing machines/dryers, so does that make them dangerous!
RE: Ground strap required on external cabinet doors?
I think high fault currents are not the concern. 120V is enough to really hurt someone and is not so high as to be able to "drain" across a corroded hinge. So if someone grabs the door, whammo, "Hello 120V".
Thanks for all the advice!
RE: Ground strap required on external cabinet doors?
RE: Ground strap required on external cabinet doors?
There's more than one way to skin a cat. There's more than one way to ground a door. Some are better than others, but many can be considered sufficient depending on the application. Beauty is in the eye of the beholder.
RE: Ground strap required on external cabinet doors?
RE: Ground strap required on external cabinet doors?
The “West Coast” mention may be related to EUSERC metering standards for low- and medium-voltage metalclad sections that periodically require energized access by unsuspecting utility folks.
No offense, but low-bid switchgear providers continue to keenly excel in outdoing their peers in what they affectionately call “doors,” and particularly “hinges,” that are (surprise) wishfully intended to remain serviceable for 30 years.
RE: Ground strap required on external cabinet doors?
RE: Ground strap required on external cabinet doors?
I resemble and resent that statement!!!
RE: Ground strap required on external cabinet doors?
I don't know the theorectical reasons why bonding jumpers are needed other than to provide safety to people and protect equipment.As the previous threads indicate,it may be a lot of other reasons as well.
I have seen cabinet doors and transformer enclosures that show a distinct burnt mark around the enclosure bolt heads.At times these marks are in each bolt head on an enclosure.I do remember a time when we energized a new Power Tranformer and fire shot out around the bolt heads fastening the Secondary JB to the main transformer tub.
There were close to 50 , 3/8" bolts fastening the JB to the tub.Obviously added bonding was the answer.
GusD
RE: Ground strap required on external cabinet doors?
RE: Ground strap required on external cabinet doors?
RE: Ground strap required on external cabinet doors?