Siemens residential load panel question (USA)

[Paul Conners]

I installed a Siemens 200A combo meter & load panel (catalog # MC2442B1200SEC
or FEC). Not yet inspected or live.

The panel is delivered configured for underground service but can be
reconfigured to accept overhead service. All that is required is for the
service conductors' lugs to be relocated above the meter. These photos show
the panel after reconfiguring for overhead service.

<http://tinypic.com/m/b4zrcw/3>

<http://tinypic.com/m/b4zrdk/3>

The service bus is one flat bar of *very* soft aluminum. The lug attaches to
the bus with a 8 mm bolt & nut (no lock washer).

This assembly (bar & lug) can be installed "up" or "down" depending on
whether overhead or underground service is used, by removing the assembly,
inverting it, and reinstalling.

Note that the service bus bar connects only to the meter bus via a black 5 mm
self-tapping screw. Everything below the black screw is simply plastic
supports.

The attachment of the service bus bar to the meter for an expected maximum
100A (per phase) seems more than this tiny screw is designed for. The
majority of current doesn't flow through the screw, of course, but through
the contact of the bus bar and the meter bus. These 2 pieces are held
together with 5 mm screw.

Am I the only one who thinks this is a lightweight design for such a critical
connection?

Thanks.

 

[Bill]

I'm sure that is fine. Be sure to read and follow all directions for this
and also maybe call the manufacturer and ask if aluminum wiring
"anti-oxidation" goop should be applied where the busses contact.

Also the tightness in inch pounds, that screw should be tightened, with a
torque wrench. (12 inch pounds equals one foot pound.)

*Very* important with main connections that they be the correct tightness.
And because aluminum, not too tight because it may strip.

But if not tight enough, the connection can heat up and fail. Same with lug
nuts. There should be a label on the panel which says how tight the lug nuts
should be torqued.



"Paul Conners" wrote in message

 

[Paul Conners]

*Very* important with main connections that they be the correct tightness.

And because aluminum, not too tight because it may strip.

But if not tight enough, the connection can heat up and fail. Same with lug
nuts. There should be a label on the panel which says how tight the lug nuts
should be torqued.

The torque spec for lug nuts (the nuts that hold the lug to the bus bar) are
provided on a sticker inside the panel. I was surprised to not see any
mention of torque for the allen screw *in* the lug or the small 5 mm screw.

Will be asking Siemens about those...

Thanks.