Voltage on cabinet base plate

DLMUK

Member
D
Join Date
Jun 2013
Location
Southampton
Posts
311
Hi,

This is hopefully a simple question to answer for someone...

I have a small cabinet which just has a 240VAC input, connected to an AC>DC converter (Meanwell 24VDC PSU) and then a few terminal blocks distributing the AC to a couple of locations.

Everything in the box is new.

When placing a probe of a DMM between the live input terminal and the base plate of my junction box it reads 240VAC.

The base plate is earthed to the 24V PSU and to the mains input earth.

I can remove every connection other than the mains AC input and still measure the voltage, there are not shorts etc between the input and the base plate/earth.

Is this normal?

I have two junction boxes doing the same thing but I am just surprised to be able to measure the 240VAC.

thanks,
 
DLMUK said:
Hi,

This is hopefully a simple question to answer for someone...

I have a small cabinet which just has a 240VAC input, connected to an AC>DC converter (Meanwell 24VDC PSU) and then a few terminal blocks distributing the AC to a couple of locations.

Everything in the box is new.

When placing a probe of a DMM between the live input terminal and the base plate of my junction box it reads 240VAC.

The base plate is earthed to the 24V PSU and to the mains input earth.

I can remove every connection other than the mains AC input and still measure the voltage, there are not shorts etc between the input and the base plate/earth.

Is this normal?

I have two junction boxes doing the same thing but I am just surprised to be able to measure the 240VAC.

thanks,
Click to expand...

This is normal.

You should be reading 240VAC between the input terminal and the base plate. The base plate is grounded and I'm guessing the 240V service is grounded (earthed) at the source, so they have a common reference point.

You are reading the difference in voltage between the 2 points. If the terminal was live and you read 0V between the live terminal and the base plate, then I'd start worrying.
 

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