Grounded vs. Ungrounded Station Service

[marks1080]

Generally, I'd like everyone's opinion on using a grounded vs. ungrounded system for station service at a sub station. Typically we have always used grounded. Typical loads for new stations would be 600 : 120/208. Personally I like things that are grounded, from a safety point of view, although I have heard some compelling arguments as to why an ungrounded system, equiped with a ground fault moitor, may be better.

Thanks!

 

[Power0020]

Most LV equipment won't tolerate a voltage doubled due to ungrounded system fault, the IT system usually uses an isolation transformer to avoid this as the potential w.r.t. ground can be lethal with no fault detection (RCDs, insulation monitoring).

I believe this will add much more cost

 

[waross]

In many areas t is a code requirement to solidly ground 120/208 Volt systems. Also your 600 Volt system must be grounded if there are any line to neutral loads such as 347 Volt lighting circuits.

Bill
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"Why not the best?"
Jimmy Carter