Installation · Specification

How many string lights can you connect end to end?

Four numbers decide it: the conductor gauge, the rating of the plug and cord set, the total load of the bulbs you fit, and any maximum the maker states for that build. The run stops at the lowest of the four. Ask what the reference you are quoting prints for each of them.

The short answer: no single number covers outdoor string lights. Work out the load your bulbs draw, check it against the cable and plug printed for the reference you are quoting, and treat any maximum stated for that build as the ceiling. iLamp Technology (Shenzhen iLamp Technology Co., Ltd) prints the length, the socket count, the cable and the plug for every string reference. Ask whether a maximum number of strings is printed for the reference you want, and have the answer written on your quotation alongside the rest of the specification you sign off against your sample.

The four limits, and which one bites first

Conductor gauge	Every metre of cable carries the current of every string beyond it, so the cable nearest the plug works hardest. A 20 AWG cord and an 18 AWG cord of the same length are not the same conductor. The gauge is printed per reference, and two references of the same length and socket count can print different gauges.
Plug and cord set	The moulded plug and its lead carry the whole run. A US two-prong, an EU two-round-pin and a UK three-pin build are different cord sets. Ask what the plug on your reference is rated at, and ask for the same answer for the end connector.
Total load	Sockets multiplied by the watts of the bulb you fit. The socket count drives the load, not the length: a 100 ft G40 string with 50 sockets (ILT-STR-022) carries more than a 100 ft S14 string with 30 sockets (ILT-STR-005) when both are fitted with the same bulb.
A stated maximum	Where a maker prints a maximum on a tag or an instruction sheet, it is the result of a test on that exact build. It is not arithmetic you can redo from a spec sheet, and it does not carry over to another reference, another bulb wattage or another cord set. Ask whether one is printed for the reference you want.

The arithmetic you can do yourself

Count the sockets

Take the socket count printed for the reference. Length tells you how much cable you are buying, not how much load you are switching on.

Multiply by the bulb

Sockets × the watts of the bulb you intend to sell = the load of one string. Use your bulb, not the one that happened to arrive with the sample.

Divide by the voltage

Watts ÷ supply voltage = the current one string draws, near enough for sizing. That current passes through every metre of cable between the plug and that string.

Add the run, then stop short

Add the strings you want on one plug, compare the total with the lowest of the four limits, and leave headroom rather than sitting on it.

Worked example. ILT-STR-014 is a 100 ft / 30 m S14 string with 30 suspension sockets on a 230 V EU plug. Fit a 2 W bulb in every socket and one string draws 60 W, about 0.26 A at 230 V. If your layout calls for three of them on one plug, that run draws 180 W, about 0.78 A. The sum sizes the load. It does not say how many strings may be joined. Ask whether a maximum is printed for ILT-STR-014, and have the answer written on your quotation.

120 V and 230 V runs are not the same sum

The same bulbs draw the same watts on either supply, and roughly half the current at 230 V. A 230 V run therefore reaches a current limit later than a 120 V run of the same load. It does not follow that more strings may be joined. The plug, the cord set, the end connector and any stated maximum all belong to the 230 V build, and the installation rules of the destination market decide the circuit behind the socket.

The cable printed per reference reflects that split. The 120 V S14 strings print an AWG gauge: 20AWG SJTW (ILT-STR-004) or 18AWG SJTW (ILT-STR-007) at the same 48FT length and 15 sockets. The 230 V EU and UK S14 strings print a millimetre figure instead of an AWG gauge (ILT-STR-013, ILT-STR-015); read it from that reference's own spec table and have it confirmed on your quotation. The G40 strings print SPT-1W (ILT-STR-022) and the ST38 strings SPT-1 (ILT-STR-002). Quote the reference, and the cable comes with it.

Read the cable and socket count for the reference you are quoting

Ref.	Family and plug	Length	Sockets	Cable
ILT-STR-004	S14, US 2 Prong, 120V US plug	48FT / 14.6M	15pcs Suspension	20AWG SJTW
ILT-STR-007	S14, US 2 Prong, 120V US plug	48FT / 14.6M	15pcs Suspension	18AWG SJTW
ILT-STR-005	S14, US 2 Prong, 120V US plug	100FT / 30M	30pcs Suspension	20AWG SJTW
ILT-STR-014	S14, EU 2 Round F, 230V EU and UK plug	100FT / 30M	30pcs Suspension	0.75mm2SJTW
ILT-STR-022	G40, US 2 Prong, 120V US plug	100FT/ 30M	50pcs	SPT-1W
ILT-STR-002	ST38, 120/240V	100FT / 30M	50 pcs Suspension	SPT-1

Figures are as the factory prints them per reference. Where a printed figure is not fully legible, it is confirmed on your quotation. The full set of references, with inner-box sizes and weights, sits on the outdoor string lights page, and the bulb shapes behind the socket counts are compared in the bulb shapes guide.

A dimmer or controller in the run has its own printed limit

Put a dimmer between the socket and the strings and its rating caps the run, whatever the cable would allow. The factory’s 120 V dimmers print 240 W, 360 W and 650 W ratings (ILT-STR-025 to ILT-STR-030) and its 230 V dimmer prints 500 W (ILT-STR-031, ILT-STR-032). Count the load of every string behind the dimmer against that figure. Check the dimmer’s own lead too: the 650 W references print 16 AWG SJTW where the 240 W and 360 W references print 18 AWG SJTW.

What to check on your sample

Read the tag and the instruction sheet packed with the sample, and write down any maximum they print.
Measure the current one string draws with the bulb you intend to sell fitted in every socket.
Join two strings and check that the connector seats fully and closes over the pins.
Leave the joined set running outdoors overnight, then check the plug and the first connector for warmth.
Check that the load marked on the string agrees with the bulb wattage on your order.

What to put on your enquiry

The reference and the factory code you want quoted.
Length and socket count, and the bulb shape and wattage for each socket.
Plug type and supply voltage for the destination market.
Cable gauge or conductor cross-section, if your buyer specifies one.
How many strings you want on one plug, and how many runs on the installation.
Whether a dimmer or a controller sits in the run, and its rating.

Then ask whether a maximum number of strings is printed for that exact reference, with the cable, plug and bulb the sample was built with, and have the answer written on your quotation.

Where the method stops

The arithmetic sizes a load. It does not clear a circuit. Watts divided by volts is an approximation, and an LED driver draws a little more current than that sum suggests, which is another reason to leave headroom. The supply, its protection and the installation rules belong to the destination market and to the electrician who signs the work off. Treat the figures above as specification input for your own design review, not as advice for a particular installation.

Documents to ask for with the quotation

The factory states its string lights carry an ETL listing and CE and RoHS markings; the listing card, the declaration of conformity and the test reports are requested and will be published here when received. Until then, ask for them with your quotation and treat the marks as the factory’s statement. The US question of a seasonal versus an all-year string is set out in the UL 588 guide, the EU and UK rules in the CE and energy label guide, and what exists per family and market in the documents register.

Questions buyers ask

Can I join strings from two different references?

Treat them as separate runs unless the factory confirms otherwise for both references. Two references can print different conductor gauges, different plugs and different connectors, and a stated maximum belongs to one build only. Joining a 20 AWG string behind an 18 AWG one puts the whole run on the thinner conductor. Ask the desk to confirm compatibility for the exact codes you are quoting, and have the answer written on your quotation.

Do the bulbs at the far end look dimmer on a long run?

Voltage falls along any long conductor, so the far end of a heavily loaded run sits below the supply voltage. LED filament bulbs draw little, so the effect is usually small, but it grows with socket count, with bulb wattage and with the number of strings joined. If the look of a long run matters to your buyer, test it at full length with your own bulbs before you commit to the layout.

Does a 230 V run take more strings than a 120 V one?

Not automatically. The same bulbs draw the same watts on either supply and roughly half the current at 230 V, so a current limit arrives later. The plug, the cord set, the connector and any stated maximum are different on a 230 V build, and installation rules differ by market. Use whatever maximum is stated for the reference you are buying, not a figure carried across from the other voltage.

Where is the maximum number printed?

Where a maker publishes one, it sits on the string’s own tag or in the instruction sheet packed with it, as the result of its own test. Read it on the sample you approve, because it belongs to that build. Change the cable, the plug, the bulb wattage or the socket count and the number changes with it. Ask the desk whether one is printed for your reference and keep the answer on your quotation.

Does the length or the socket count decide the load?

The socket count. Length changes how much cable you hang and how far the voltage has to travel, but the load is the number of sockets multiplied by the watts of the bulb in each one. A 100 ft G40 string with 50 sockets carries a heavier load than a 100 ft S14 string with 30 sockets fitted with the same bulb. Check the socket count printed for the reference before sizing a run.

Reviewed September 2026

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