Hi,
I have come across many Access control (RFID) readers support single gang box mounting but when i checked the dimensions of various such reader its not same.
Like,
Conekt Mobile-Ready Contactless Smartcard Reader
(Size: 76 mm × 130 mm × 30 mm)
XPass D2 Outdoor Compact RFID Reader
(Size: 80mm x 130mm x 25mm)
what is single gang box mounting ? is there any standard body who defines the gang box size ? how hgang box mounting helps for installer and end customer ?
What the manufacturer is referring to is the standardized dimensions of a single gang box and the screw holes that are on that box. In other words if a reader is stated as being single gang box mountable then you can mount the reader to the single gang box without any modifications. This is no different than say light switch and outlet covers. They all are single gang box mountable but there are various sizes of those covers just the same as a reader will come in different sizes.
Hi Shannon,
thank you for your reply.
is there any body who define standardized dimensions of a single gang box ?
Which dimension is more popular in single gang box, any idea on this ?
NEMA.org is the organization that sets these standards in the United States. As far as which dimensions are more popular the only real difference is the depth of the box versus new or old work box and whether metal or plastic. Again the key feature reader manufacturers are adhering to are the distance of the screw holes which are set to be 3.28" apart center to center.
Where you will see the noticeably different sizes are the actual plates put over the boxes. For instance I added an outlet for a TV I mounted on the wall a few months ago. There were three different cover plate dimensions to choose from. Of course I picked the wrong one to match the existing. Often you will see oversize plate covers due to the sheet rock not being cut properly.
In Europe they have a completely different standard. I actually have a European reader and it is more square than rectangle.
Another term manufacturers have started using is calling the reader a "Switch Plate Reader."
The term 'single gang' is approximate, because actual sizes depend on what type of single-gang box it is. For example 'new construction' and 'old work' sizes are smaller than 'retrofit', which are again different from metal vs. plastic.
Like Shannon mentions, whether it is a single-gang 'switch' vs 'utility'/'device' box is sometimes a factor too.
Electrical work is concerned mostly with safe conductor fill capacity rather than interchangeability of cover plates. Meanwhile, if you're installing devices into/onto boxes, it can be a thorny issue.
I wish there were better/more definite sizes too, but there can be different exact sizes from one job to the next depending on the age of building and when in construction a box was installed.
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