Installation guide

DECarray Site Preparation

5. Are any devices that are not UL or IEC approved connected to the same

breaker as any of the DSSI computer equipment?

If the previous conditions do not exist, then the grounding should be adequate

for DSSI operation. Digital recommends that the ground offset voltage between

any two enclosures be measured. However, this only provides data for that

particular moment in time. Ground offset values may change as additional

devices are connected to the same power source.

If the installation exhibits ground offset voltages between interconnected

enclosures that exceed the allowable limits, use one of the following solutions:

1. Have an electrician correct any deﬁciencies detected during the power

system survey. This is the recommended solution.

2. Install grounding cables between enclosures. Grounding cables are

available from Digital, and come with the necessary hardware for

installation.

Installing additional grounding cables normally reduces the ground voltage

offset sufﬁciently to meet the requirements. In severe cases, however,

the cables may not be large enough. This is revealed by the ground

offset voltage measurements. If the additional grounding cables are not

adequate, the source of the ground offset voltage must be traced and either

reduced or eliminated.

2–4 DECarray Site Preparation