Re: Contactor question <Control Panels '05 NEC>

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Sparktron01@xxxxxxxxxxx 

David

Theoretically yes, however, NO ONE will try to get UL or IEC ratings
on such a contactor design.  Invariably, one contact will lead or lag
(and get over loaded).  Use a contactor rated for the worse case current.

A good rule of thumb is size the contactor as no less then 125% of
main fuse (or branch circuit) over current protection.   Also be aware
that with new 2005 NEC, control panels have to have a short circuit
current rating placarded on the panel, and input (branch circuit) OCP
must have a let through worse case SC current LESS THAN control
panel rating or installation will fail electrical inspection.

There have been explosions, fires, injuries and deaths by not following
this design parameter (new article 408 IIRC).

Regards
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA. USA


> Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
>
> Hi all,
>
> Just a quick question about relay contactors. Let's say that I have
> a 4-pole, 30 FLA inductive per pole rated contactor. Does this mean
> that I will have up 120 amp inductive rating of the contact points if I
> use all 4 of the poles in a parallel or series parallel fashion in a single
> circuit to switch my pole pig transformer under a load?
>
> Thanks,
> David Rieben
>
>