Are there any specific volt drop limits for connectable installations? Or is it counted in the total limits prescribed in 3000? Do we need to make allowence so that VD never exceeds those limits when designing? This could be very difficult when ever time they connect the VD up to that point could be a different value
Or is it just assumed that they should be small enough that VD shouldn't be an issue?
Volt drop in connectable installations?
Re: Volt drop in connectable installations?
A "connectable installation" is, always, supplied from a point in an "electrical installation" - generally a socket outlet.
The volt drop limits of "3000" apply to the socket outlet the CI plugs into (and "3001" provides guidance for estimating max demand within a caravan park).
No allowance / correction factor is made to cater for the additional VD within the CI.
So it is reasonable to assume that voltage at any service pillar anywhere in the country will not be less than (230 V -6% - 5%).
That's the 6% allowed at POS by ESRs; and the 5 % allowed by "3000". So 216.2 V at POS; and 205.4 at socket on pillar
As you say, it's not feasible to work out what it actually is for any particular service pillar at any given time;
and it will generally be higher than this assumed minimum.
VD within the supply lead is constrained by rules about CSA vs length for given nominal current rating.
And VD within the CI itself is limited by the short runs and minimum cable size requirements.
I suspect that the reason no specific limit is set by "3001", "3004' or "6115" is simply that setting one would be rather complex;
If set WRT full rated current would be over-restrictive in normal use of a large CI.
That doesn't mean we should just ignore it altogether; and cable sizes for large CIs should be increased accordingly.
In fact coming new edition of "3001" calls for minimum size of 2.5mm2.
The volt drop limits of "3000" apply to the socket outlet the CI plugs into (and "3001" provides guidance for estimating max demand within a caravan park).
No allowance / correction factor is made to cater for the additional VD within the CI.
So it is reasonable to assume that voltage at any service pillar anywhere in the country will not be less than (230 V -6% - 5%).
That's the 6% allowed at POS by ESRs; and the 5 % allowed by "3000". So 216.2 V at POS; and 205.4 at socket on pillar
As you say, it's not feasible to work out what it actually is for any particular service pillar at any given time;
and it will generally be higher than this assumed minimum.
VD within the supply lead is constrained by rules about CSA vs length for given nominal current rating.
And VD within the CI itself is limited by the short runs and minimum cable size requirements.
I suspect that the reason no specific limit is set by "3001", "3004' or "6115" is simply that setting one would be rather complex;
If set WRT full rated current would be over-restrictive in normal use of a large CI.
That doesn't mean we should just ignore it altogether; and cable sizes for large CIs should be increased accordingly.
In fact coming new edition of "3001" calls for minimum size of 2.5mm2.
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Re: Volt drop in connectable installations?
Thanks Alec, thought that may be the case
Interesting about the 2.5mm size as well!
Interesting about the 2.5mm size as well!