WattsOn (including Mark II & MCM) Fuse/Breaker Requirements

The WattsOn & WattsOn-Mark II Power Meters require fuses on the input to the voltage terminals at some point within the system. In some cases, the voltage may be tapped off of existing fuses or breakers. If this is not possible, Elkor recommends a 1A or lower fuse for protection of the installation wiring. The meter voltage inputs draw negligible current (less than 0.3mA max).

The voltage rating of the fuse must match or exceed that of the installation. Elkor sells a ganged three-position fuse holder for use in 600V installations (i-Block-FUSE):

The i-Block may be purchased with or without the CT shorting terminals (not necessary when used with mA output CTs).

Note that the meters themselves require a 24VDC/VAC (see individual meter specifications) power supply.  In the case of the WattsOn-Mark II kits, or the WattsOn-MCM, there is a 120/240-to-24VDC power supply incorporated in the enclosure.  This is a 10W power supply, and draws very little current, but on startup can briefly draw a higher amount, up to 20A, for a fraction of a second.  This usually isn’t enough to trip most breakers, but 1A fuses may trip, in this case, Elkor recommends a 5A fuse.

Elkor recommends using the “smallest practical” breaker size.  Smaller sizes are often very expensive, but 5/10/15A is acceptable.

In all cases, proper wiring techniques must be undertaken by qualified personnel only. Please observe all National and Local wiring codes and requirements.

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2011-07-21 17:53:09

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