Fusing the WattNode
Overview
There must be a fuse or circuit breaker of appropriate rating protecting the WattNode® meter.
However, in many cases, the circuit being monitored is already protected by fuses or circuit breakers and there is no need for additional protection for the meter.
Download: Fusing the WattNode - Application note on adding fuses to your WattNode® meter installation. It lists recommended suppliers and part numbers.
Guidelines
- If you are monitoring a branch circuit rated for 30A or less, you can safely depend on the existing circuit breakers or fuses to protect the meter and its wiring, so there should be no need for additional fuses.
- If you are monitoring a high current branch circuit (>30A), you have two choices:
- Tap off of the high current circuit into lower current fuses or breakers, then into the WattNode meter.
- Find a low current (30A or less) circuit on the same phases as the circuit you wish to monitor and connect the voltage terminals (green screw terminals) on the WattNode meter to this low current circuit. In this case you won't need additional fuses. The only downside to this approach is that if this low-current circuit is turned off or interrupted, the meter will lose power, even though the load being monitored may still be powered.
For customers that are monitoring multiple branch loads in one panel, it is common to use one low current (15A or 20A) breaker or fuse block to power the multiple WattNode meters, then put the various current transformers around the wires for the different branch circuits being monitored. This has the advantage that you can remove and apply power to the meters during installation without turning off regular branch circuits. This does require space in the panel for the extra breakers unless you use fuses.
See Also
Keywords: fusing, fuse, circuit breaker, over-current
