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.

Approve the complete run, not just its wattage

Keep the load calculation and the permitted connection limit as separate entries on the acceptance sheet. UL Solutions' October 2024 guidance describes a maximum connected-load marking for all-year string lights under UL 588 Supplement SD, whose stated scope is factory-assembled, parallel-connected strings rated at no more than 120 V. This U.S. certification and installation guidance supplies no universal connection count and does not establish that a particular iLamp Technology reference falls within that category.

Record the permitted build. Ask for the exact model's marked connection limit and instructions, then record the bulb load separately. Include the cord, plug, end connectors, dimmer or controller and their applicable load ratings in the review; do not use unused wattage capacity to exceed the marked limit.
Specify the mounting. Ask the installer to check the approved supports, span and mounting method against the product instructions. The same UL guidance describes hanging provisions for the covered lamp holders and instructions against hanging other objects from the cord, wire or string.
Test the proposed full run. Have a qualified tester assess the actual bulbs, joined-string count, supply and control combination within all stated limits. Record current, connector and cord temperature checks, behaviour at the far end, and starting from cold and after warm-up. If a dimmer is fitted, include the intended low setting. Agree the test conditions and acceptance criteria before sampling; a successful demonstration does not raise a marked rating.

For a different U.S. category, CPSC's seasonal-lighting guidance identifies minimum wire size, strain relief and overcurrent protection as construction safeguards for portable, plug-connected, temporary-use products with nominal 120 V input. Its section 15(j) rule does not itself trigger section 14(a) testing or certification. Use that defined scope when requesting construction details; it neither approves an all-year installation nor determines a 230 V string's connection limit.

Limits for the complete run

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	Follow the maximum stated by the manufacturer for the exact configuration and request its supporting rating and conditions. 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 ÷ power factor = the current one string draws. An LED driver's power factor is below 1, so watts ÷ volts alone understates the current: at a power factor of 0.8 the real figure is 25 % higher. 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. The 100 ft / 30 m S14 string (ILT-STR-014) has 30 suspension sockets on a 230 V EU plug. Fit a 2 W bulb in every socket and the nominal bulb load of one string is 60 W. If your layout calls for three of them on one plug, the nominal bulb load is 180 W. Current also depends on the actual power factor; request the electrical data for the approved bulb and string combination. This example totals bulb wattage only. 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

Use bulbs and strings rated for the specified supply. A connection limit for a 120 V configuration says nothing about the limit for a 230 V configuration. 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. The EU 2 Round F builds are ILT-STR-013 to ILT-STR-015; the separate UK GB 3 G builds are ILT-STR-016 to ILT-STR-018. Read the cable from the exact reference's own spec table and ask for it 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 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. 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.

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.
Have electrical and temperature checks performed by a qualified tester using the approved configuration and the manufacturer's instructions.
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 and by the power factor is a sizing figure, not a measurement; ask for the power factor of the bulb or driver you specify, and leave headroom above the result. 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 for string-light runs

Shenzhen iLamp Technology Co., Ltd appears in Intertek's ETL Listed directory: UL 588 string lights for year-round use and controllers for seasonal decorative lighting strings · UL 1993 self-ballasted LED lamps · UL 153 portable luminaires · UL 1310 Class 2 power supplies, each with its Canadian counterpart. Your quotation states which listing, if any, covers the model you order. See the directory records →

Historical copies and issuer records are in the documents register, and your quotation names the current documents for the exact model, voltage and destination market. 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 the documents to match to each 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. The complete combination needs confirmation against each component's rating. 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. Check the complete proposed run; socket count, bulb wattage and the number of joined strings affect the load. 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. Each voltage configuration needs its own confirmed connection limit and correctly rated bulbs. 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.

Ask about connection limits on WhatsApp Telegram: t.me/ryanfulfil

Notes

Specification figures: where a printed figure is not fully legible, it is confirmed on your quotation.

Documents: which of the models you are quoting fall under each Intertek directory listing is confirmed on your quotation. Request the current declaration of conformity and supporting reports, and match the scope of historical copies and issuer records to your order.