Hi. Cutting things fine here, so an opinion on voltage drops would be nice.
Doing some work on customers shed supply which is a bit of a cludge right now.
I am trying to re-use rather long, but existing (measured and verified R1+R2 and IR ) buried & concreted over 1.5MM SWA to a customers shed.
Expected demand is 1KW laser cutter for small business plus lighting. Total is genuinely not expected to be > 6A for 99% of the time, but customer also wants sockets for micro-tools for craft work which might ba an extra ~ 1A or so.
The shed supply is sadly on a long ~25M length of existing 1.5MM SWA, buried under concrete. I need to be inventive with current-demand to stay within the recommended voltage drops (3% for the lighting). ie if customer did chose to use the full 10A, I would be expecting at 3..4% drop.
The 1.5mm SWA and installation method can take just over 20A with installation rating factors. Taking discrimination into account suggests maximum 20A MCB at house to protect the cable, and to fit MCB's 10A+3A at the shed (with RCD CU in shed). (maybe nicer to use 16A at house and 10A+2A in shed, but 2A MCBs are hard to get.)
This would suit the current customer, and 6..7A max is the expected demand. If a user was to max out (at risk of popping the shed 10A MCB) with say ~2KW garden machinery, the ~ 10A total would give us voltage drop problems for the lighting (3..4% region).
Existing small cable size limits me here, but trying to keep cost and workload sensible and re-use.
Opinions here.
I believe I am covered on the safety side, but is it “Responsible” business to install only 10A + 3A MCB’s in a garden shed type situation in which the maximum load (for example 2KW garden machinery load) voltage drops could exceed 3% for the lighting?
Current customer doesn WANT to use any garden machinery, and voltage drops will be just OK using the ~ 6..7A demand of the customers currently expected equipment.
Doing some work on customers shed supply which is a bit of a cludge right now.
I am trying to re-use rather long, but existing (measured and verified R1+R2 and IR ) buried & concreted over 1.5MM SWA to a customers shed.
Expected demand is 1KW laser cutter for small business plus lighting. Total is genuinely not expected to be > 6A for 99% of the time, but customer also wants sockets for micro-tools for craft work which might ba an extra ~ 1A or so.
The shed supply is sadly on a long ~25M length of existing 1.5MM SWA, buried under concrete. I need to be inventive with current-demand to stay within the recommended voltage drops (3% for the lighting). ie if customer did chose to use the full 10A, I would be expecting at 3..4% drop.
The 1.5mm SWA and installation method can take just over 20A with installation rating factors. Taking discrimination into account suggests maximum 20A MCB at house to protect the cable, and to fit MCB's 10A+3A at the shed (with RCD CU in shed). (maybe nicer to use 16A at house and 10A+2A in shed, but 2A MCBs are hard to get.)
This would suit the current customer, and 6..7A max is the expected demand. If a user was to max out (at risk of popping the shed 10A MCB) with say ~2KW garden machinery, the ~ 10A total would give us voltage drop problems for the lighting (3..4% region).
Existing small cable size limits me here, but trying to keep cost and workload sensible and re-use.
Opinions here.
I believe I am covered on the safety side, but is it “Responsible” business to install only 10A + 3A MCB’s in a garden shed type situation in which the maximum load (for example 2KW garden machinery load) voltage drops could exceed 3% for the lighting?
Current customer doesn WANT to use any garden machinery, and voltage drops will be just OK using the ~ 6..7A demand of the customers currently expected equipment.
