portable building protection

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A portable building has a 3 way board controlled via 63a 100mma trip. This is fed via a messy three phase tns system. The protable building has lights, sockets & heater circuits.
The electrical components were installed and certified by the party supplying the building.

Surely the board should be covered by a 30ma rcd instead of a 100ma?
 
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If the sockets are 13A types, and intended to supply outdoor equipment, then strictly yes, 30mA RCD, at least on sockets supplying, or reasonably expected to supply, outdoor portable appliances.

100mA, slow acting, RCD trips are normally used with TT supplies as a "kill everything" breaker, guaranteed to fire, even if the earth impedance is not low enough to blow the main fuse. (which with a temporary installation is very possible, if you are hammering earth rods in locally, into who knows what, and if I were designing the building I'd assume the worst case of a really bad earth.)
In such a case an additional fast acting 30mA breaker is often used downstream from the 100ma one for sockets only, as this reduces the risk of total blackout from one appliance or damaged cable, and makes it safer for cables to go outside.
Otherwise non RCD protected sockets ought to be at least marked as not for outdoor use, or made non-standard in some other way, to avoid the cable going out of doors.
M.
 
thanks m,

it is expected that the equipment is to be used outside. The supply is not tt, but a tns set up.

That is why i feel it should have 30ma protection. As it stands, the sockets can and are being used outside with 100ma protection.

(the 100ma rcd tripped in 45ms at X 1.)

Is the manufacturer at fault here? Anyone else have similar problems with portable buildings?
 
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