I am in the process of moving my main service and will be using the present location for a subpanel. I already have one sub panel on the other end of the house that would be fed downstream from this new subpanel. Does this violate the code. I can only find examples where one subpanel is shown. An alternative would be to basically run both panels from the new main. Is this legal? Thanks in advance. Sullymon
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If done right it doesn't violate the code. Either way. Make sure you go with a four-wire feed from first point of disconnect, main panel, to the sub panel/s. Also size the feeders correctly.
Not to get too touchy but if you don't know how to set up sub panels what makes you think that you know enough to move the service. Sounds to me like you would do well to bring in an electrical contractor.
Service will be moved by the power company. I know how to wire the panels( extra wire for the ground bus), have the code for sizing wires, conduit, etc. just struck me that I never saw any reference to panels in series and started wondering if their was a problem with it. In the end it will all be inspected by the building dept, I just wanted to avoid wasting time... Thanks
Feeding a sub from a sub isn't prohibited by Code, but there's a reason you don't see it very often. It's called overcurrent protection device coordination.
That is electrician-speak for making sure that the circuit breakers trip in the right sequence--the one closest to the short, fault, or overload should open (trip) first.
If the series of panels doesn't have OCPD coordination, a problem in a branch circuit may trip a feeder breaker instead of the branch circuit breaker. In some instances, it may trip a feeder breaker in the main panel, a couple of subpanels back.
This isn't good--at the least, it makes it very hard to find the problem and restopre power. Coordination involves interpreting the trip curves for the breakers and calculating the available fault current in the various parts of the circuit. For residential installations, no one bothers to do this.
My two cents--feed each subpanel from the main panel.
Oh, and don't think that an inspection will necessarily be thorough enough to identify problems with your work. Just like any other aspect of construction, there can be installation mistakes that aren't obvious (even in a thorough inspection) and that don't show up until much later. With plumbing, it may be a leaking solder joint; with electrical, a fire or electrocution.
Good luck.
Cliff
Edited 2/20/2005 5:24 pm ET by CAP