ECN Forum Forums General Topics of the Trade General Discussion Area line side of disconnect

Is there a requirement for line side conductors to be terminated on the top of a disconnect, or was that just a known way to do it. Been seeing alot of factory wired equipment pre-wired with the line conductors expected to terminate at the bottom of the disconnect device (breaker).
For 35 years, this was always unexceptable to me...line top, load bottom.

That's a good question.

I also thought line was on top. I thought line had to be on top so the arc squelch mechanism operated correctly when the breaker opens.

In the trade for about 1/2 of that 35, and I too remember it the same way, but have noticed that it is no longer the case. I'm sure it was a requirement at some point, but can't tell you when it was removed - But I think "Line" was stamped at the top for everything for quite some time after that. "line on top" - is something that I was always told....

Or, maybe the last vestages of any wording that may have implied it are in 404.6(A-C)

"Single-throw knife switches shall be placed so that gravity will not tend to close them." And, by design... it ended up that way - 'Line on top'.

I'm not 100% sure, but I believe the issue is, you are required to connect in the manner proscribed by the device manufacturer, and they almost all say Line on top, Load on bottom. If you have to do it differently for some reason, you have to get special labels indicating the change so that some future electrician would not make a careless mistake by assuming the convention. I got that info from an inspector on a job where I had to back-feed a main circuit breaker.

Not many single throw switching devices are marked line and load anymore.

Fused disconnects have to de-energize the fuses, that eliminates any options with those.

Most breakers can be used any direction,


I agree it is a good idea bit the inspector was asking for something that is not required by the NEC


Once you get to double throw (a manual ATS for example) that goes out the window.

The only limiting rule is the way the handle operates.

I think that 404.6 is about it for code regarding this.

Thanks for the replies