ECN Forum Forums Code Related Discussion NEC & other Code issues Emon Dmon Location of Inline Fuses or Fuse Blocks

These sub metering systems have always been a heated topic of discussion in the field. There are very few switchboards that have an extra three phase fused disconnect sitting there just waiting for the installer to hook into. Because the meters are so small there are very few places to connect the wire feeding these units to whatever method you end up using for protection. Many people have asked me if they could just slide the # 12 wires feeding the meters under a larger lug feeding something else. Unless the lug is rated for this it is in violation of the code. They also request using individual in-line fuse holders for the required fusing but then there are some disconnecting issues here as well. This type of installation always posses a dilemma to those of us who are the AHJ. Which articles of the code do we enforce and which ones do we let slide. I’d like to see what other people allow when someone asks to tap a switchboard that has no provisions for expansion and wants to feed one of these meters.

Regards,

Tony

My post above regards installing a fused disco adjacent to the gear being monitored, not necessarially a 3-pole within the 'gear'.

The 5 amp (mfg spec) fuses tend to pose situation to some EC's. IMHO, I see no issue with a 3 gang 'finger safe' midget fuse block, IF there is adequate space. A 3-pole CB is the 'disco' in this case.

Now, 'large' gear.....a Code compliant 'tap' to a fused disconnect switch....that works.

Quote:
"This type of installation always posses a dilemma to those of us who are the AHJ. Which articles of the code do we enforce and which ones do we let slide. I’d like to see what other people allow when someone asks to tap a switchboard that has no provisions for expansion and wants to feed one of these meters."

I (we) have to enforce the NEC, as adopted by NJ, as the EC's have to comply with it. I have done the 'tap' as an EC, as described above. I have not seen any sub-meter installs as an AHJ recently, but have approved 3 permit apps.