Cable entry into a cabinet/panel is usually done from bottom. But is there any advantages for this?
Are there any standard recommending it? What is wrong in having top entry?

 

If the conduit gets water - condensate or contamination - it pools in the bottom of the loop rather than pouring into your electrical equipment.

 

A potential problem with top entry is water infiltration; it's happened to me.

 

If you're in a wet environment water can puddle on the top and seep through the penetration, even if somewhat sealed. Main power frequently enters through the top, as it usually goes through a disconnect from top to bottom, etc.

 

The design of your panel will determine the best entry method. Bottom entry means that when the holes are drilled for the conduit ports, chips do not land on your equipment or get rapped in the terminals, causing problems down the road. Top entry is fine, there are problems associated with cable or wire support - sticky back tie wrap supports will always come loose or fall off. Plus if you preferr bottom entry, your cables can easily be routed to a cable tray or panduit wire tray for breakout to terminals in a cleaner, more professional manner.

I don't know of a published standard - UL or NEC does not address the issue directly. Electricians will put conduit holes where ever it is best suited for them without regard to the equipment layout inside your panel. The other consideration is that in a wet environment, top entires leak - period.

By the way, entry is not usually from the bottom, I have seen, top, bottom and side entries all the time. In my opinion bottom entries are better, with side entries being the next preferred method, but agan, layout of your panel, and suitable working space for wiring is the first thing to look at. If you can pre-plan a entry location, the better, but don't count on the electrician putting the conduits where you want them.


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The main advantage of bottom entry is that it maintains the integrity of the junction box against water. Rain and/or condensate in the conduit can destroy the wiring of a junction box in short order. Even with the best seals and drains on the conduit, I have had damage from water entering through top entry.

John Beck
Control System Specialist, Retired

 

> From my experience, this is only dependent on the application and site conditions.

Normally entarnce is from bottom, but if it's water station or there is a possibility for liquids leakage, top entry is the standard.
and so on..

( Complete thread: http://www.control.com/1026175441/index_html )

 

The main reason for bottom entry is because electricians are notorious for not using the proper fittings. Putting the entry on the bottomm means its less likely to leak water or other fluids into the cabinet if exposed to rain or hosedown.

 

I believe that no one can easily determine which way you enter the cables is recommended.
Many factors shall be taken in consideration such as type of sites,application,cable trays or conduts routing,environment...but I`m sure that presence of consultants on site will handle all this questions and will beobliged to do what they want..other wise you will not get your money