6 ms·

These things are handy for devices that use the higher current when fully operational, but need power for initial setup. In IT, the main thing that comes to min

by orev 6y ago

These things are handy for devices that use the higher current when fully operational, but need power for initial setup. In IT, the main thing that comes to mind are managed PDUs. You want to be able to power up the control unit to get things like networking configured, and you don’t want to be doing that while standing in the data center balancing a laptop on your knee. With this, you can get it setup in the office, then go in and start pulling floor tiles to get it plugged in to the high Amp plug with all the settings pre-configured. To be clear, when you’re doing the setup you don’t have any actual equipment connected to the PDU; you’re just getting power to the unit itself to get power to the management circuitry.

decker 6y ago
This makes a lot of sense. The post definitely lacked context about whether the cable was in use or if it was just something found in the server room. It's a shame the author simply assumed other people are stupid rather than bothering to investigate and understand what's going on.
- closeparen 6y ago
  Do you think everyone who finds this cable will investigate and understand what's going on before they deploy it in a way that starts a fire? It's not usually this easy to do something this wrong.
  - deleted 6y ago
    [deleted]
  - hyperman1 6y ago
    Not even that. After a fire has started for a completely different reason, the fire insurance company inspector comes in and finds it. You know, the person that loves to find any half reason to not pay you. Why are you even paying fire insurance when this thing even lies unconnected on a shelf.
    - Reelin 6y ago
      Can they typically deny coverage even if the violation wasn't related to the fire?
      - HenryBemis 6y ago
        They are trying to determine the root cause. Hacing it stowed away somewhere, unrelated to the fire is not an issue. But that will give them the nudge to start investigating 'everything electric that was plugged in'. And do you remember that cheap iphone charger and cable you got from ebay for $1? If the report from Fire Department's investigators point to that very corner of the house where the charger was plugged in..... (fill in the gaps.. the insurance investigator will do the same). Edit: don't get me started on that 3m cable you bought from AliExpress ;)
  - pdkl95 6y ago
    Indeed; of course there are times it might be necessary to work around safety features. The problem happens when they are not labeled properly! When the end of the cable looks like normal with a standard connector, this type of workaround cable becomes an "attractive nuisance" that people will accidentally use. If you need to make a non-standard cable - especially if it bypasses safety features - you have a responsibility to mark the cable so anyone that finds it (possibly by accident) will understand the cable is non-standard and dangerous! (alternatively: destroy the workaround cable after using it) When I used to make an ethernet crossover cable, I would find some way to label it "crossover" and I would put 3 high-contrast stripes at each end with zip-ties so it was obvious looking at either end that the cable was unusual. A non-standard and dangerous power cable should at a minimum have big, obvious labels and warning indicators at both ends!
  - paul_f 6y ago
    If the equipment is designed for 20A and plugged into a 15A circuit, wouldn't the 15A breaker trip long before it could start a fire? Seems the main problem would be constantly resetting the breaker.
    - user5994461 6y ago
      It's a maximum rating, it's very unlikely that the equipment behind the cable is using anywhere near that. By the way 20A is the typical plug and cable in a home, it's really not hinting at special equipment. If the equipment really used 20A continuously (100% sure it doesn't or it would be rated higher), it will take a long long time for the circuit breaker to heat up and trigger, like a whole hour. See charts https://en.wikipedia.org/wiki/Circuit_breaker#Standard_current_ratings https://en.wikipedia.org/wiki/Circuit_breaker#Standard_curre...
stickfigure 6y ago
Pretty much everyone that owns an RV (in the US) has an adapter that converts the 14-50P (50 amp!) plug on the RV to a 5-15P that can be plugged into common household sockets. You can't run the A/C without popping a breaker but it'll keep the fridge and lights on. The breaker, not the connector, provides safety.
- Hydraulix989 6y ago
  The breaker is there to protect against faults, not someone intentionally violating what it is protecting against.
  - samatman 6y ago
    The breaker is there to break the circuit if it exceeds the breaker's rated capacity. It doesn't care why that's happening, and it shouldn't. The cable has no way to intentionally violate the breaker: if you try to pull 20 amps out of a 15 amp breaker, it will trip.
    - rumanator 6y ago
      It sounds you're describing faults, aren't you? I mean, don't you agree that exceeding the breaker's capacity is a fault? https://en.wikipedia.org/wiki/Circuit_breaker https://en.wikipedia.org/wiki/Circuit_breaker I don't believe this is up for discussion: the circuit breaker is a device that is designed and used to protect a circuit against fault conditions. That's the whole point of their use: if a fault condition is detected, the circuit breaker breaks the circuit to about the fault to propagate or damage the circuit and/or any device connected to it.
  - Reelin 6y ago
    Not true. Breakers are most definitely intended to protect against overcurrent situations regardless of whether it's user or equipment caused. (For example, unintentionally plugging 30 amps of kitchen appliances into a single 20 amp circuit. Don't ask how I know.) That being said, you should never intentionally rely on a safety feature to cut you out - they exist as a backup in case you screw up. The 14-50P to 5-15P adapter referred to by GP is an example of "I know what I'm doing". Just be sure to double check that you really do. Edit: Also, consider that if you're in a jurisdiction where it's legal to have a 15 amp receptacle on a 20 amp circuit (many places in the US unfortunately) then a cable like this could allow you to draw a sustained current above what the receptacle is rated for but below what would trip the breaker. That's a fire hazard.

by orev 6y ago

decker 6y ago

This makes a lot of sense. The post definitely lacked context about whether the cable was in use or if it was just something found in the server room. It's a shame the author simply assumed other people are stupid rather than bothering to investigate and understand what's going on.

closeparen 6y ago
Do you think everyone who finds this cable will investigate and understand what's going on before they deploy it in a way that starts a fire? It's not usually this easy to do something this wrong.
- deleted 6y ago
  [deleted]
- hyperman1 6y ago
  Not even that. After a fire has started for a completely different reason, the fire insurance company inspector comes in and finds it. You know, the person that loves to find any half reason to not pay you. Why are you even paying fire insurance when this thing even lies unconnected on a shelf.
  - Reelin 6y ago
    Can they typically deny coverage even if the violation wasn't related to the fire?
    - HenryBemis 6y ago
      They are trying to determine the root cause. Hacing it stowed away somewhere, unrelated to the fire is not an issue. But that will give them the nudge to start investigating 'everything electric that was plugged in'. And do you remember that cheap iphone charger and cable you got from ebay for $1? If the report from Fire Department's investigators point to that very corner of the house where the charger was plugged in..... (fill in the gaps.. the insurance investigator will do the same). Edit: don't get me started on that 3m cable you bought from AliExpress ;)
- pdkl95 6y ago
  Indeed; of course there are times it might be necessary to work around safety features. The problem happens when they are not labeled properly! When the end of the cable looks like normal with a standard connector, this type of workaround cable becomes an "attractive nuisance" that people will accidentally use. If you need to make a non-standard cable - especially if it bypasses safety features - you have a responsibility to mark the cable so anyone that finds it (possibly by accident) will understand the cable is non-standard and dangerous! (alternatively: destroy the workaround cable after using it) When I used to make an ethernet crossover cable, I would find some way to label it "crossover" and I would put 3 high-contrast stripes at each end with zip-ties so it was obvious looking at either end that the cable was unusual. A non-standard and dangerous power cable should at a minimum have big, obvious labels and warning indicators at both ends!
- paul_f 6y ago
  If the equipment is designed for 20A and plugged into a 15A circuit, wouldn't the 15A breaker trip long before it could start a fire? Seems the main problem would be constantly resetting the breaker.
  - user5994461 6y ago
    It's a maximum rating, it's very unlikely that the equipment behind the cable is using anywhere near that. By the way 20A is the typical plug and cable in a home, it's really not hinting at special equipment. If the equipment really used 20A continuously (100% sure it doesn't or it would be rated higher), it will take a long long time for the circuit breaker to heat up and trigger, like a whole hour. See charts https://en.wikipedia.org/wiki/Circuit_breaker#Standard_current_ratings https://en.wikipedia.org/wiki/Circuit_breaker#Standard_curre...

stickfigure 6y ago

Pretty much everyone that owns an RV (in the US) has an adapter that converts the 14-50P (50 amp!) plug on the RV to a 5-15P that can be plugged into common household sockets. You can't run the A/C without popping a breaker but it'll keep the fridge and lights on. The breaker, not the connector, provides safety.

Hydraulix989 6y ago
The breaker is there to protect against faults, not someone intentionally violating what it is protecting against.
- samatman 6y ago
  The breaker is there to break the circuit if it exceeds the breaker's rated capacity. It doesn't care why that's happening, and it shouldn't. The cable has no way to intentionally violate the breaker: if you try to pull 20 amps out of a 15 amp breaker, it will trip.
  - rumanator 6y ago
    It sounds you're describing faults, aren't you? I mean, don't you agree that exceeding the breaker's capacity is a fault? https://en.wikipedia.org/wiki/Circuit_breaker https://en.wikipedia.org/wiki/Circuit_breaker I don't believe this is up for discussion: the circuit breaker is a device that is designed and used to protect a circuit against fault conditions. That's the whole point of their use: if a fault condition is detected, the circuit breaker breaks the circuit to about the fault to propagate or damage the circuit and/or any device connected to it.
- Reelin 6y ago
  Not true. Breakers are most definitely intended to protect against overcurrent situations regardless of whether it's user or equipment caused. (For example, unintentionally plugging 30 amps of kitchen appliances into a single 20 amp circuit. Don't ask how I know.) That being said, you should never intentionally rely on a safety feature to cut you out - they exist as a backup in case you screw up. The 14-50P to 5-15P adapter referred to by GP is an example of "I know what I'm doing". Just be sure to double check that you really do. Edit: Also, consider that if you're in a jurisdiction where it's legal to have a 15 amp receptacle on a 20 amp circuit (many places in the US unfortunately) then a cable like this could allow you to draw a sustained current above what the receptacle is rated for but below what would trip the breaker. That's a fire hazard.