On Apr 17, 11:38 am, "Robert11" wrote:
Hello,

Having a new service box installed in a residence.

Electrician has never used these before, so thought I'd ask here.

Was thinking of purchasing, and having him install, an Intermatic Whole
House Surge Suppressor
Model 4870 in the new box. Have had several large lightning storms in the
past, and one nearby strike fried the control board on our furnace ! The
Intermatic unit isn't all that expensive, about $80 or so.

Any of you folks ever used this model ?

Worth doing ? Thoughts on ?

BTW: If they do ever take a big hit, do they (usually) fail open or closed
?

e.g., would the MOV's be shorting the hot to neutral/ground after a big hit,
such that the unit would have to be removed prior to re-initiating service ?

Thanks,
Bob

From what I see on the web, the unit would be fed through a standard
15A dual-pole breaker, so if it shorted, the breaker would trip, and
you'd be running normally, with no protection, until you replaced the
unit (and maybe the breaker).

The write up on the LPS unit, which another responder has linked to,
says it pretty clearly: "These SPD’s are not repairable. A defective
SPD fails short circuit, in which case the line/branch fuses or
breakers operate. A prolonged short circuit may open, and in the
process cause rupture of the SPD elements. " My guess is the sames
goes for the Intermatic.

Chip C
Toronto